Patent Application
20210213935
The invention belongs to the safety field in vehicle tire burst.
Vehicle tire burst, which is on expressways specially, is a kind of serious accident with high risk and high probability of occurrence. Tire burst safety of vehicle is a major subject which has not been effectively resolved at home and abroad. Retrieval of relevant technical literature has showed that the current technical solutions for this subject mainly contains the following. First, tire pressure monitoring system (TPMS) as a relatively mature widely is used in a variety of vehicles tire pressure detection technology. Related tests and technologies show that tire pressure monitoring can reduce the probability of tire burst, but the parameters related to tire pressure and tire temperature does not have strict correspondence with tire burst in time and space, therefore, TPMS cannot solve the problem of tire blow-out and tire blow-out safety truly in real time and effectively. Second, a tire blow-out safety, tire pressure displays and adjustable suspension system of vehicle (China patent, patent No. 97107850.5). The invention proposes a scheme of which system mainly composed of a tire pressure sensor, an electronic control device, a brake force balance device and a lift composite suspension, to realize the safety of vehicle tire blow-out through its balanced braking force and lifting control of the tire blow-out wheel suspension. However, the technical solution for system structure and control method are relatively simple, effect of lateral stability control of the vehicle is not satisfactory. Third, tire blow-out safety and stability control system of vehicle (China Patent, patent No. 01128885.x). The invention proposes a scheme of which a system of tire blow-out safety and stability control of vehicle is based on anti-lock braking system (ABS), vehicle stability control system (VSC); the system uses a brake force regulator composed of high-speed switch solenoid valves to distributing the braking force of each wheel, thus to realize safety and stability control of the vehicle tire blow-out. Although the technical solution gives a prototype of tire blow-out safety control system of the vehicle, a higher technology platform is required to solve the major technical problem of tire blow-out safety by making a major breakthrough in technical problems, such as tire blow-out status, tire blow-out judgement, stable deceleration and steady state control of vehicle. Fourth, a method and system of tire blow-out safety control of vehicle (China Patent, No. 200810119655.5)”. The invention proposes a technical scheme about maintaining vehicle original running direction by steering assist motor control; the technical solution has a certain effect in controlling the original direction of vehicle tire blow-out, but it is difficult to achieve the purpose of safe and stable control of the vehicle tire blow-out by controlling simply the original direction of the vehicle in the actual control process. Fifth, the system and method for blow-out tire brake control (China Patent, No. 201310403290). The system and method propose a technical scheme of wheel brake control through the difference signal of brake anti-lock control of blow-out tire wheel and non-tire burst wheels of the vehicle; the braking force involved in the solution does not consider related technical problems such as wheel and vehicle stability control, so that it is difficult to achieve the purpose of safety control of vehicle tire blow-out. With development of modern electronic technology, automatic control technology and vehicle safety technology, it is necessary to introduce a new safe and stable control method for vehicle tire blow-out, to solve this major problem which has long plagued to the vehicle tire blow-out safety. Based on “a tire blow-out safety, tire pressure displays and adjustable suspension system of vehicle, the U.S. Pat. No. 97,107,850.5, the application date: Dec. 30, 1997” and “a safety and stability control system of tire blow-out of vehicle, the patent Ser. No. 01/128,885x, the application date: Sep. 24, 2001”, the patentee and collaborator of the China Invention Patents propose a new technical scheme of safety and stability control method for vehicle tire blow-out, and hopes that the significant technology topic of vehicle tire blow-out safety may be solved by the new design concept and technical scheme.
Purpose of the invention is to provide a safety and stability control method for vehicle tire blow-out (hereinafter referred to as the method) Based on vehicle braking, driving, steering and suspension system of vehicle, the method can realize independent and coordinated controls of braking, driving, steering, engine or/and suspension for tire burst vehicle. The object of the invention is realized in this way: this method adopts mode, model and algorithm of tire burst safety and stability control, to realize structured program or software design for tire burst master control and tire burst control. The method sets the information unit, tire burst controller and execution unit, which cover vehicle driven by chemical energy or electric, vehicle of or driverless. Vehicle driver by man vehicles sets tire burst master controller. The driverless vehicle set central controller. The controllers include tire burst information collection and processing, parameter calculation, tire burst mode identification, tire burst judgement, tire burst control entering and exiting, control mode conversion, manual operation control or/and networking controller. Tire burst mode identification and tire burst judgement adopt indirect or direct way. The indirect way include characteristic tire pressure or state tire pressure, and the direct way uses tire pressure sensor; tire burst judgment is realized by tire burst mode identification of state tire pressure and tire pressure detection. The tire burst control is a stable deceleration control of wheels and vehicles, and is a stability control of vehicle direction, vehicle attitude, lane keeping, path tracking, collision avoidance and balance control of vehicle body. The purpose of the invention is realized in follow way. The tire burst determination and tire burst control involved by the method is based on the process of tire burst state. In the state process, an independent and coordinated control is realized by adjustment of whole dynamic process of vehicle and state control of braking, driving, steering, engine output or/and lifting adjustment of suspension. The tire burst control and controller mainly adopt following coordination, self-adaptive and active control modes. The control mode includes the following three active control modes and controllers. First, control modes and controller of tire blow-out for driven by man vehicle. The vehicle uses compatible mode of manual intervention control and active control for tire burst. The tire burst controller is set independently and can share equipment and resources of vehicle, such as the sensor, the electronic control unit which includes structure and function modules and actuator. The method sets tire blow-out judgment, control mode converting and tire blow-out controller. The tire blow-out judgement modes includes of detection tire pressure, state tire pressure and characteristic tire pressure judging types. Conversion of control mode mainly adopts converting of control mode between normal and tire blow-out working conditions, the converting of control mode between active control and manual intervention control in the tire blow-out working condition. The tire burst controller mainly adopts a compatible control mode of active control and manual intervention control for tire burst. Second. The tire blow-out control mode and controller for driverless vehicle with a manual auxiliary operation interface. The controller can realize tire blow-out control by means of the artificial interfaces of driving, braking and steering, and can share the sensors, machine vision, communication, navigation, positioning and artificial intelligence controllers of in-vehicle system of driverless vehicle. The controller sets tire blow-out and non-tire blowout judgment, control mode conversion and tire blow-out control which include tire blow-out collision avoidance, tire blow-out path tracking and tire blow-out posture control of driverless vehicle by environment perception, navigation, positioning, path planning and vehicle control decision including tire blow-out control decision. Tire blow-out judgment mainly adopts three modes of wheel detecting tire pressure, state tire pressure and characteristic tire pressure. The control mode conversion mainly adopts two way: a conversion way between driverless control in normal working condition and driverless control of intervening by manual operation interface, another conversion between driverless control in normal working condition and active control in tire blow-out working condition. The tire blow-out controller mainly adopts two compatible control mode: a compatible control of driverless control of vehicle with manual intervention or without manual operation interface, another compatible control of driverless or driven by man control and active control of tire blow-out vehicle with manual operation interface or without manual operation interface. Third, tire blow-out control and controller of driverless vehicle. The tire blow-out controller can share sensor, machine vision, communication, positioning, navigation and artificial intelligence controller with vehicle mounted system. The controller sets tire blow-out judgement, control mode conversion and tire blow-out controller. Under condition of which vehicle network has been constructed, and as a networking vehicle, an artificial intelligence networking controller is sets up to realize driverless controls which include tire blow-out control, coordination control of tire blow-out and collision avoidance and path tracking of the vehicle, by means of environmental awareness, positioning, navigation, path planning and control decision of vehicle. The tire blow-out judgement mainly adopts three determination modes: detection tire pressure, state tire pressure and characteristic tire pressure of vehicle. The control mode conversion mainly adopts following conversion way: a conversion between control of driverless vehicle in normal working condition and active control of driverless vehicle in tire blow-out working condition. The above control mode conversion is realized by the switching of coordination signals of the tire blow-out control. Based on the above control modes, the stable deceleration of blow-out tire vehicle and the steady state control of the whole vehicle are realized by coordinated adjusting of active anti-skid drive, engine braking, stable braking of brake, electronically control throttle and fuel injection of engine, power assistance steering, or/and electronic controlled or drive-by-wire steering and passive, half-active or active suspension.
(1). The information unit set in this method is mainly composed of sensors set by vehicle control system, tire burst control related sensors or signal acquisition and processing circuit. Based on the tire burst control structure and process, tire burst safety and stability control mode, model and algorithm, the tire burst control program or software is developed. The software adopts non modular or modular structure. In the process of tire burst control, the controller directly or through the data bus obtain the sensor detection signal output by the information unit, or obtain the vehicle Internet and global positioning navigation signal, mobile communication signal processed by the central computer or electronic control unit. The output signal of controller controls engine or electric vehicle power device, to adjust its power output. The output signal controls the brake regulator to adjust the braking force of each wheel and the whole vehicle. The output signal controls the power steering device to realize the control of steering rotational moment for tire burst. The output signal control the steering system by wire to adjusts the directive wheel angle θe or and rotation torque of steering wheel exerted by ground. The tire burst control for speed, active steering and path tracking can realized. When the exiting signal of tire burst control comes, the tire burst control of vehicle exit. The output signal controls the corresponding regulator and actuator set in execution unit to realize the control of each regulated object.
(2). The method introduces the concept of tire burst instability states for vehicle after tire burst, it includes two instability: tire burst instability of vehicle and control instability for tire burst vehicle to normal working condition. In the method, a concept of non equivalent and equivalent relative parameters and their deviations are introduced, so as to realize the comparison to equivalence and nonequivalence state parameters of each wheel under normal and tire burst conditions. This method introduces the concept of state tire pressure, a generalized tire pressure concept that is determined by the mathematical model and algorithm of wheel and vehicle structure state parameters and control parameters. Detecting tire pressure does not take as the only technical feature to determine tire burst. In a category including tire pressure, wheel angle velocity, angle acceleration and deceleration speed, slip rate, adhesion coefficient and vehicle yaw rate, the concept of tire burst state, tire burst characteristic parameters and parameter values are defined. The tire burst state process is determined quantitatively, and the tire burst state process and control process are integrated, thus, it make the state and control function become a continuous function in time and space. They are both related and continuous functions in the inter domain. This method defines the concept of tire burst judgment, and uses a fuzzy, conceptualized and stativization tire blow out judgment. As long as the wheel vehicle enters a specific state, it can be determined as a tire burst. It does not need to determine whether the vehicle has a real tire burst, and then enters the tire burst control. In this method, there is no need to set up a tire pressure sensor or reduce its detection conditions. It provides a practical feasibility for indirect measurement of tire pressure and tire burst control based on indirect measurement. The tire burst control to set or do not set tire pressure sensor is determined. This method establishes a mechanism and mode of entering and exiting of tire burst control, so that the vehicle can enter or exit from tire burst control in real time without real tire burst. Without the exiting mechanism of burst control, it is impossible to define tire blow out status, and there is no tire burst control based on the stativization, fuzzy and conceptualized tire burst control. In this method, the tire burst control modes such as active entering, automatic exiting in real-time and manual exiting are set according to the state of the wheel and vehicle. The artificial controller is set up to realize manual exiting to tire burst control, to realize docking of artificial control and active control for tire burst, to realize a certain control of uncertain tire burst, so that, the tire burst and tire burst control with the rapid change of wheel and vehicle state parameters have practical controllability and operability. The method determines the existence of critical point, inflection point and singularity of parameters to tire burst state and tire burst control. Based on these points, using the condition and threshold model, the tire burst control can be divided into different stages or time zones, including state point of pre period to tire burst, real tire burst period, inflection point period and separation of tires and rims. The piecewise continuous or discontinuous function control mode is adopted, to make the tire blow out control adapt to the tire burst and its state. This method adopts the conversion mode and structure of program, protocol or converter, and takes the tire burst signal as the conversion signal to realize the control and control mode conversion between normal and blow out conditions. Based on the driving, braking, engine, steering and suspension systems of driven by man or driverless vehicles, this method adopts the methods, modes, models and algorithms of tire burst master control, subsystem coordination and independent control to realize the coordinated control and composition of braking by engine, braking by braking equipment, engine output, steering wheel rotation force of steering wheel, active steering and body balance. A relatively complete tire burst control structure is designed. The driving, braking, steering, engine and suspension control of vehicle are constituted as an external cycle under normal conditions. The entering of tire burst control, tire burst control process, exiting of tire blow out control exiting, and control of drive, brake, steering, engine and suspension are constituted as the internal cycle under tire burst conditions. At the critical point, inflexion point, singular point and other points of tire burst or the transition period of each control stage, the parameters of wheel structure and motion state change rapidly. By reducing the steady-state control braking force for the tire burst wheel, reducing the balanced braking force of each wheel, increasing the differential braking force of each wheel in the stability control of the whole vehicle, and changing wheel angle acceleration and deceleration speed or and slip ratio that are equivalent to the braking force as control parameters, by changing the control mode of vehicle driving, braking, rotation force of steering wheel and rotation angle of steering wheel, the double instability of wheel and vehicle control under the condition of rapid change of instantaneous state of wheel and vehicle is solved successfully. This method integrates the control of normal and tire burst conditions of wheels and vehicles, allows the overlap of normal and tire burst conditions, and successfully solves control conflict between normal and tire burst conditions. Tire safety and stability control of vehicle are a kind of steady-state deceleration control of wheels and vehicles, a kind of stability control of vehicle direction, vehicle attitude, lane keeping, path tracking, collision avoidance and body balance.
(3). In order to accurately and concisely describe the content of the method, the method adopts necessary technical parameters and mathematical formulas. The technical parameters use two way or mode of expressions: words and letters. The two expressions way of words and letters are equivalent completely. Mathematical model uses two means of expression. First, the pre-letter of model indicates type of the mathematical model, the pre-letter is followed by parenthesis, and the letters in parentheses indicate modeling parameters; the concrete form is: Q (x, y, z). Second, the pre-letter indicates type of function model, and the equal sign is set after the letter; after the equal sign, function form is represented by letter, the letter of function in brackets is followed by a bracket, and the letters in the parenthesis are parameters and variables. The concrete form is: Q=f(x, y, z). In description of content of the method, the technical term of “normal working condition and tire blow-out condition” is used. The normal working condition refers to all running states of vehicle except the tire blow-out (tire burst) of the vehicle, and the tire blow-out condition refers to running states of vehicle in tire burst of wheel. The concept of tire blow-out and non-tire blow-out is defined by the method.
Based on tire burst control structure, mode and process of driven by man and driverless vehicles, the method adopts following steps.
1). Parameter Calculation and Calculator
The parameters that are used in tire burst control of wheel may be determined by field test, parameters of sensor detection, mathematical model and algorithm. According to needs of control process of vehicle, the corresponding parameters and parameter values which include wheel angle acceleration and deceleration, slip rate, adhesion coefficient, vehicle speed, dynamic load, or/and effective rolling radius of the wheel, vertical and horizontal acceleration and deceleration of the vehicle are determined in real time. The observer of mathematics is used to estimate the physical quantities which are difficult to measure. Physical quantities estimation of the sideslip angle to vehicle mass center are determined by the global positioning system (GPS) or the observer based on the extended Kalman filter. The controller set by the method and system mounted by vehicle can share data and parameters detected by sensors and calculation parameters of vehicle, through physical wiring in vehicle or data bus which includes CNA.
2). Tire Burst Pattern Recognition and Tire Burst Judgment of Vehicle
Tire burst control of vehicle adopts a tire burst pattern recognition of characteristic tire pressure and state tire pressure. Based on the pattern recognition, a pattern and model of tire burst judgment are established, to realize tire burst judgment. Definition of vehicle tire burst: whether the tire burst of wheel is real or not, as long as showing of features for “abnormal state” characterized by motion state and structural mechanics parameters of wheel, steering mechanics state parameters of vehicle, vehicle running state and tire burst control parameters which are as a quantitative index are revealed, a qualitative condition and a quantitative model of tire burst judgement is established on the basis of tire burst pattern recognition; based on the condition and model of tire burst judgement, the tire burst of vehicle is determined when the qualitative conditions and quantitative condition are achieved. Defining characteristic and state tire pressures: the pressures are determined by characteristics of abnormal state under normal and tire burst conditions of the wheel and vehicle. According to the definition of tire burst, the characteristics of tire burst state determined this method are consistent with the characteristics of abnormal state under normal and tire burst conditions of the wheel and vehicle, and the characteristics are consistent with the state characteristics generated by the wheel, vehicle steering and the whole vehicle after the real tire burst of vehicle. The so-called consistent of state characteristics to both of them means that the two characteristics are same or equivalent basically. State tire pressure includes several characteristic tire pressures and it is constituted by characteristic tire pressure. The state pressure has combination characteristic of characteristic tire pressure. The characteristic tire pressure and the state tire pressure are dynamic in tire burst control. According to tire burst state process and the tire burst control process, tire burst judgement are divided into two stages. First stage: the determination stage of tire burst state pattern recognition. Based on abnormal state of wheel and vehicle under normal working conditions, the tire burst mode recognition, tire burst determination, entering and or exiting of tire burst control are determined by mechanical state parameters of wheel, steering of vehicle, vehicle motion and tire burst control. Second stage: determination stage of pattern recognition of tire burst control: based on tire burst control, the tire burst pattern recognition and judgement are determined by control parameters in tire burst control state. The continuing of tire burst control or its control exiting are determined by the tire burst judgement in the stage. In this method, the tire burst pattern recognition for state tire pressure or tire pressure detected by sensor is used. Tire burst pattern recognition of state tire pressure is a tire burst pattern recognition determined by feature parameters of motion state of wheel, steering mechanics state of vehicle and vehicle state. State tire pressure pre is not a real tire pressure of wheel, it is consistent with the abnormal state characteristics of wheel and vehicle under normal and tire burst conditions, and is consistent with the state characteristics of wheels, steering vehicle and whole vehicle after the real tire burst. The so-called consistent of state characteristics means: they are basically same or equivalent. The states of vehicle is expressed by quantitative parameters or/and qualitative condition, which include states of wheel movement and steering, attitude, lane maintenance and path tracking of vehicle. The tire burst determination of tire pressure detected by sensor or state tire pressure is a process judgement of tire pressure. The determination of tire burst is based on the qualitative condition or quantitative model of tire burst recognition mode. The judgement period Hv for tire burst is set; the tire burst judgement is realized in the logical cycle of its period Hv.
(1). Tire burst pattern recognition of vehicle in the state stage of tire burst. Defining tire burst pattern recognition and its judgment. According to kinematics state and parameters of wheel, steering of vehicle and vehicle, the tire burst pattern recognition is determined by identification of abnormal state of vehicle under tire burst and normal working condition.
i. Tire burst pattern recognition of characteristic tire pressure xb of wheel motion state, the xb is referred to as pattern recognition of characteristic tire pressure. The xb is made by comparison of a same parameter which is determined by non-equivalent relative parameters Dk and equivalent relative parameters De of wheelset of vehicle. The Dk and De are basis of vehicle tire burst pattern recognition determined by wheel motion state. Defining relative parameters Db of two-wheels of wheelset: same parameters is adopted by two-wheel of wheelset. Defining non equivalent relative parameters Dk: relative parameters Db which are not processed by equivalence are defined as the non equivalent relative parameter of two-wheel of wheelset. Defining same parameter of parameters assemble En: value of relative parameters Db which are adopted by two-wheels of wheelset are equal or equivalent equal. Defining equivalent relative parameters De of two-wheels of wheelset: under condition of which one or more parameters taken in the parameters assemble En are equal or equivalent equal to two-wheel of wheelset, The one or more parameters taken in the non-equivalent relative parameters Dk characterized by motion state of two-wheels of wheelset are converted to one or more parameters De of the equivalent relative parameters of two-wheel for wheelset by converting models and algorithms. The non-equivalent relative parameters Dk includes braking force of wheel, rotation angle velocity of wheel and the slip ratio of wheel. The same parameters En includes braking force or driving force of wheel, moment inertia of wheel, friction coefficient and load of wheel, side declination angle of wheel, rotation angle of steering wheel, inner and outer wheel turning radius of vehicle. The equivalent relative parameters De include braking force, rotation angle velocity and slip ratio of wheel. According to equivalent processing of conversion model and algorithm, equivalent relevant parameters Dk are converted to the equivalent relative parameters De, under conditions of which parameters taken of two-wheels of wheelset in same parameters assemble En are equal or equivalent equal, the equivalent relative parameters De is determined by no equivalent relative parameters Dk. Any one parameter in equivalent relative parameters De of two-wheels of wheelset is determined by non-equivalent relative parameters Dk by means of equivalent treatment of transformation model and algorithm in which values of the parameters taken from the same parameters En are equal or equivalent equal. When state parameters of two wheels of wheelset are compared, the equivalent treatment can eliminate and isolate uncertainty effect to tire burst judgement, under conditions of which parameter value of two wheels of wheelset in En are not equal or not equivalent equal. The equivalent processing to parameters Dk can determine quantitatively the comparable relationship of state parameters that include braking force, rotational angular speed and slip rate of wheels. The tire burst pattern recognition may determine whether there is tire burst and tire burst wheel by equivalent treatment and comparison in same parameter taken by E. In order to simplify the comparison of the parameters in Dk and De, the deviation or proportional mode of e(Dk) or e(De) can be used to comparing of tire burst and no tire burst wheel. The non-equivalent, equivalent relative parameter deviation and the ratio of two wheels are defined as: In two wheels of wheelset, the deviation e(Dk) or e(De) between Dk1 or De1 of wheel 1 and Dk2 or De2 of wheel 2 is defined:
e(Dk)=Dk1−Dk2e(De)=De1−De2
in two wheels of wheelset, the ratio e(Dk) or e(De) between Dk1 De1 of wheel 1 and the Dk2
De2 of wheel 2 is defined:
Based on the e(Dk) and e(De), model and function model of the characteristic tire pressure xb for mode recognition of tire burst of wheel motion state are established. In the same parameter set En, the parameter En is taken as E1 . . . En-1, En; a set of characteristic tire pressures xb to parameter En(E1 . . . En-1, En) is formed by different parameters and number of parameters taken by xb.
x
b(e(ωk))xb=f(e(ωe))
Specific expression of characteristic tire pressure of the set xb:
x
b[xb1,xb2 . . . xbn−1,xbn].
When the parameter in non-equivalent relative parameter Dk is non-equivalent relative angle velocity deviation e(ωk) of two wheel of wheelset and the parameters in the same parameter En is taken as braking force of two-wheel, characteristic tire pressure xb1 inset xb is function of the equivalent relative angle velocity deviation e(ωd1) by which two-wheels of wheelset use same braking force Qi. When the parameter in non-equivalent relative parameter Dk is non-equivalent relative angle velocity deviation e(ωk) of two-wheel and the parameters in the same parameter En are taken as wheel braking force Qi and friction coefficient μi, characteristic tire pressure xb2 inset xb is function of the equivalent relative angle velocity deviation e(ωd2) by which two-wheel of wheelset use same Qi and The equivalent relative angle velocity deviation e(ωd2) is determined by the no-equivalent relative angle velocity deviation e(ωk2) for Qi and which in two-wheels of wheelset are equal or equivalent. The set of characteristic tire pressure xb: xb[xb1, xb2]. The equivalent relative angle velocity deviation e(ωe) of the two-wheel in the formula can is replaced by the equivalent relative slip rate deviation e(se) each other. Tire burst state mode recognition are determined by the division of control states of vehicle for non-braking and non-driving, driving, braking, straight and steering running control states of vehicle. In tire burst judgment of wheel motion state, the set of characteristic tire pressures can be determined:
x
b[xb1,xb2 . . . xbn-1,xbn].
The conversion model between no-equivalent relative state parameters Dk and equivalent relative state parameters De are simplified by the division of different control states of vehicles, to adapt the judgement of tire burst under different control and motion states of vehicles. The judgement of tire burst for wheel motion state usually adopts the pattern recognition with deviation or proportion of equivalent or no-equivalent relative parameter (De or Dk) of two-wheel of balanced wheelset. Defining balance wheel set: the wheelset determined by two moment of opposite direction exerted on centroid of the vehicle is defined as balance wheelset; the moment parameter include the braking force, driving force or ground force exerted on the two wheels. Based on the tire burst pattern recognition of characteristic tire pressure set xb, a tire burst judgment logic for determining front and rear axles or wheelset of diagonal alignment arrangement is established. Based on this judgment logic, tire burst wheel, tire burst wheelset or tire burst balancing wheel pair are determined.
ii. Tire burst pattern recognition of characteristic tire pressure xc for vehicle steering mechanics state. This pattern recognition is determined by steering mechanics state of vehicle. During generation and formation of tire burst rotation moment Mb′, the Mb′ is transferred to steering wheel by steering system and it will be changed that tire burst state, size and direction of rotation torque Mc of rotation angle and rotational moment of steering wheel. When Mb′ reaches a critical state, the generation and state of tire burst rotation moment Mb′ can be identified, and direction of tire burst rotation moment Mb′ can be determined by the change characteristics of rotation angle δ and rotation torque Mc of steering wheel. The critical state of Mb′ can be determined by a critical point of angle δ and torque Mc of steering wheel. In process of tire burst, the angle δ and torque Mc of steering wheel change in size and direction, and the δ and Mc of steering wheel reaches a “specific point” which can identify tire burst. The “specific point” is called critical point of δ and Mc. Coordinate system of the size and direction of angle δ and torque Mc and its increment Δδ and ΔMc of steering wheel are established. The coordinate system specifies origins of δ and Mc. The direction of δMc
Δδ and ΔMc are determined. Information process of Mb′, the critical points of δ and Mc are determined by the directions of δ
Mc
Δδ and ΔMc. Based on the direction of δ
Mc
Δδ
ΔMc, a judgement logic for determining burst wheel in front and rear axles or wheel pairs of diagonal arrangement is established. Tire burst wheel and tire burst wheelset or tire burst balancing wheelset are determined by this judgment logic.
iii, Tire burst pattern recognition of characteristic tire pressure xd for vehicle motion state. Under tire burst state, unbalanced yaw moment for vehicle, namely. Tire burst yaw moment Mu′ produced by wheel forces of which ground exert on tire burst wheel and other wheels to vehicle mass center result in changes of vehicle motion state and state parameters. Tire burst pattern recognition of characteristic tire pressure xd is determined by motion state and state parameters of whole vehicle. Under normal and tire burst working conditions, theoretical and actual yaw angle velocity deviation eω
x
d(eωeβ(t),{dot over (u)}x,{dot over (u)}y)
xd=f(eω
In the model, the δ is rotation angle of steering wheel, the {dot over (u)}x and the {dot over (u)}y are longitudinal and lateral acceleration and deceleration of vehicle. According to the positive or negative judgment of xd, the excessive or insufficient steering of the vehicle is determined, and tire burst wheel in front and rear axles or wheel pairs in diagonal arrangement is determined by direction of steering wheel angle δ and the judgment logic of excessive or insufficient of vehicle.
iv. One of the following two mode is used for tire burst pattern recognition of vehicle state tire pressure pre. First, tire burst pattern recognition based on state tire pressure pre characteristic function. The characteristic function of state tire pressure is called state tire pressure pre in shorter form. The state tire pressure pre is determined or constituted by the characteristic function of characteristic tire pressure xb xc and xd. The mathematical model of state tire pressure: pre=f (xb
xc
xd). In model, xb, xc, xd have same or different weight. According to process of tire burst or/and control state and type of non driving and non braking, driving or braking of the vehicle, the relevant parameters in xb
xc and xd are allocated the weight of xb
xc and xd with corresponding weight coefficients. Second, the model of tire burst pattern recognition of state tire pressure pre is established by related parameters of wheel motion state, steering mechanics state of vehicle and vehicle state that include e(ωe) and e(ωk), e(Se) and e(Sk), eω
(2). Tire burst judgment at state stage for tire burst
i. The tire burst judgement on the basis of wheel motion state. The judgement is a tire burst judgement of characteristic tire pressure xb. Based on comparison of equivalent relative parameter deviation e(De) of the left and right wheel of front and rear axles or diagonal arrangement wheelset, the tire burst pattern recognition of characteristic tire pressure xb is determined by tire burst state process and types of non-driving and non-braking, driving, braking, straight running or steering of vehicle. The deviation e(De) includes equivalent relative angle velocity deviation e(ωe) and equivalent relative slip rate deviation e(Se). The tire burst judgment model of xb is established by the modeling parameter e(ωe) or e(Se). The judgment model of tire burst includes logical threshold model and the threshold value is set. When the xb reaches the threshold value, the judgment of tire burst is determined, and tire burst wheels and tire burst wheelsets are determined.
ii. Tire burst judgment to steering mechanics state of vehicle
Tire burst judgment on the basis of mechanics state of vehicle steering. The tire burst judgment is determined by characteristic tire pressure xc. Based on the parameters of steering mechanics state of vehicle, the logic of tire burst pattern recognition of steering mechanics for the system is used to determine characteristic tire pressure xc. The tire burst pattern recognition is realized according to characteristic tire pressure xc. The tire burst pattern recognition of xc can be determined by model of using tire burst rotation moment Mb′ as parameter:
x
c(Mb′),xc=f(Mb′)
Under the conditions of vehicle straight running or steering, the direction of tire bursting rotation moment Mb′ is determined by a judgment logic of direction of angle δ, rotation moment Mc and its increment Δδ ΔMc of steering wheel. According to the judgment logic, the tire burst judgment is determined, from this, tire burst wheel, tire burst wheel pair or tire burst balance wheel pair are determined.
iii. Judgment for tire burst based on vehicle motion state
The judgment of tire burst of vehicle is a characteristic tire pressure xd. Based on the pattern recognition of vehicle motion state, a tire burst judgment model of characteristic tire pressure xd is established. The judgment model includes logic threshold model. Setting threshold value, the tire burst is determined when the value determined by threshold model reaches threshold value. According to the positive (+) or negative (−) of xd, the excessive or insufficient steering of the vehicle is determined. The tire burst wheel in front axle and rear axles or in wheelset of diagonal arrangement are determined by the judgment logic of direction of steering wheel angle δ and excessive or insufficient of vehicle.
iv. Judgment combined of tire burst based on wheel motion state and vehicle state
The tire burst judgment is determined by combined pattern recognition of wheel motion state and vehicle motion state. The tire burst judgment is a judgment of state tire pressure pre determined by functional model pre[xb, xd]. Setting the logic threshold model and threshold value of functional model of state tire pressure pre, the judgment of tire burst is determined when the value of pre reaches its threshold value, otherwise the determination of tire burst is not established. Based on control states of vehicles and types of non-driving and non-braking, driving, braking, straight running and swerve running of vehicles, excessive steering or insufficient steering of vehicles, tire burst wheel, tire burst wheelsets or tire burst balancing wheelsets are determined.
v. A logic assignment for tire burst determining is expressed by positive and negative (“+” and “−”) of mathematical symbols. The logic symbols (+, −) in the process of electronic control are expressed by high or low electric level, or specific logic symbols code including numbers and letter. When the tire burst is determined, tire burst controller or a central master computer sends a tire burst signal I.
(3). Tire burst pattern recognition in the control stage of tire burst. The pattern recognition is based on the control state of tire burst vehicle; the control parameters of wheel, steering and vehicle are adopted by Judgment of tire burst in tire burst control stage.
i. Pattern recognition of wheel state in tire burst control stage
A tire burst pattern recognition and model of the characteristic tire pressure xb is established by one of braking force deviation eq(t), angle acceleration and deceleration degree deviation eω(t) or slip rate deviation es(t) of differential brake of two-wheel for wheelset. The deviations are determined by modeling parameters of braking force Qi, angle acceleration and deceleration degree {dot over (ω)}i and slip rate Si of wheel. Based on pattern recognition and model of characteristic pressure xb, value of xb are determined.
ii, Pattern recognition of steering control in tire burst control stage.
A tire burst pattern recognition and model of the characteristic tire pressure xc is established by modeling parameters of tire burst rotation moment M′b, or deviation eM Mk2 by two steering wheels of vehicle. According to the model, the value of characteristic tire pressure xc for pattern recognition is determined.
iii, Pattern recognition of vehicle in tire burst control stage
A tire burst pattern recognition and model of the characteristic tire pressure xd is established by yaw angle rate deviation eω
iv. Combination pattern recognition of control parameters for wheel, vehicle steering and vehicle state in tire burst control stage. The combination pattern recognition is determined by pattern recognition of characteristic tire pressure xb, xc and xd, or xb and xd, namely pattern recognition of state tire pressure pre[xb, xc, xd], pre[xb, xd]. The model of state tire pressure pre is established. According to the model, value of pattern recognition of pre is determined.
(4). Tire burst Judgment in the control stage of tire burst
In process of tire burst control, the characteristics of tire burst state and the values of characteristic functions xb, xc and xd can convert each other among the characteristic functions xb, xc and xd. In view of the transfer of tire burst characteristics and eigenvalues, tire burst determination model is established by relevant parameters in xb, xc and xd. Based on control states and types of non-driving and non-braking, driving, braking, straight running and turning of vehicles, the judgment of tire burst is achieved by burst judgement model. In the control stage of tire burst of vehicle, the judgement model of state tire pressure pre[xb, xc, xd] or pre [xb, xd] is used to determine tire burst of wheel and vehicle. The judgment of tire burst uses logic threshold model. The logic threshold value is set. When the value of relevant parameters or tire pressure pre reaches the threshold value, the judgment of tire burst in tire burst control stage is maintained, and tire burst control of vehicle continues. When the value of relevant parameters or pre does not reach the threshold value, the vehicle exits from tire burst control. The judgment of tire burst determined by this method is basis of tire burst safety control of vehicle.
3). Tire Burst Pattern Recognition and Tire Burst Determination for Detected Tire Pressure
(1). Tire pressure sensing and detection of wheel. Tire pressure is detected by an active, non-contact tire pressure sensor (TPMS) set on the wheel. TPMS is mainly composed of a transmitter set on the wheel and a receiver set on body of vehicle. A unidirectional communication of radio frequency (RF) or a bidirectional communication of radio frequency (RF) and Low frequency are adopted between transmitter and receiver. The sensor of tire pressure (TPMS) is driven by electric energy. The transmitter is a high integrated chip which integrates sensor module, wake-up chip, MCU, RF transmitter chip and circuit. The sensor module includes sensors of pressure, temperature, acceleration and voltage. The sensor module uses two mode of sleep and working. The transmitter uses this technology about sleeping and wake-up, adjustable cycle of signal detection, signal emission limited by number in a certain time and automatic adjustment of signal emission cycle to maximizing satisfy of performance requirements of tire burst control system during tire burst process. The technology can extend energy supply and electric service life.
(2). Tire burst pattern recognition and tire burst determination
Tire burst pattern recognition is based on detecting tire pressure of sensor. Tire burst judgement adopts threshold model. Setting a series of decreasing logic threshold api, a series of decreasing logic threshold values of tire pressure are set from apn . . . ap2 to ap1. The apn is threshold value of standard tire pressure. The ap1 is zero value of tire pressure. When the detection value of tire pressure is large than apn, the overpressure alarm of tire will be given. When the tire pressure reaches the threshold value ap2, judgement of tire burst of wheel will be determined. The prophase stage of tire burst control is determined by apn . . . ap2. The time interval of the signal transmission cycle is determined by mathematical model of modeling parameters that include tire pressure value detected by sensor and it change rate. The time interval of signal launching cycle is decreased with decreasing of tire pressure value measured, and with the increase of change rate of tire pressure value measured. The tire pressure sensor (TPMS) and tire burst pattern recognition used by the method can meet the requirements of tire burst control in the maximum limit.
4). Entering, Exiting to Tire Burst Control and Conversion of Control and Control Mode
(1). Entering and exiting to tire burst control
i. First. Entering and exiting to tire burst control under condition of which tire burst of vehicle is determined. Qualitative condition, quantitative judgment mode and model are used to determine the entering of tire burst control. The determination of entering for tire burst control is realized by achieving the qualitative condition, or/and quantitative condition of judgment mode and model. Quantitative judgment model includes logical threshold model. The model adopts single parameter or multi-parameter threshold model. When the value determined by the threshold model reaches the threshold value, vehicle enters tire burst control, and the controller or the main control computer of the system sends the tire burst control entering signal ia. The single-parameter threshold model includes a threshold model with parameter of vehicle speed ux. The threshold value aua is a value set by vehicle speed ux. In multi-parameter threshold model, threshold value aub is determined by model with parameters that includes speed ux, steering wheel angle δ and friction coefficient μi. The aub is a function of speed ux, steering wheel angle δ or/and friction coefficient μi. The function value of aub is reduced with the increase of rotation angle δ of steering wheel. The aub is a increasing function with increment of friction coefficient μi. Second, the exiting of tire burst control under the condition of which tire burst judgement of vehicle is established. A qualitative condition, quantitative judgment mode and model are used to determine the exiting condition of tire burst control. The quantitative judgment mode and model of exiting of tire burst control are set. When reaching the exiting condition determined by the model, the exiting of tire burst control is realized. The quantitative model includes a logic threshold model. The logic threshold model uses a single parameter or multi-parameter threshold model. Determining the threshold value for the tire burst control exiting. When the threshold value determined by the threshold model is reached, the tire burst control of vehicle exits, and master controller or master control computer of tire burst issues the tire burst control exiting signal ib.
ii. Exiting of the tire burst control in the tire burst control progress of vehicle. First. Under the condition of which tire burst judgement of vehicle is true, the exiting of tire burst control is realized when the tire burst judged by one of measuring tire pressure of sensor, characteristic tire pressure and state tire pressure is not true, or the judgment of tire burst is converted from its establishment to its no establishment, tire burst control exits. Second. Exiting of tire burst control in tire burst control phase. In the tire burst control, the tire burst pattern recognition is determined by the tire burst control state and its parameters. Based on the touch recognition, the tire burst judgment is established, the tire burst judgment is maintained and the tire burst control is carried out continuously if the judgment is established. The tire burst control exits from the stage if the judgment of tire burst is not determined during this stage.
iii. Tire burst control exiting determined by manual operation interface. When the exiting signal of tire burst control determined by the manual operation controller (RCC) arrives, tire burst control exits.
iv. When burst control of vehicle entering or exiting, the master controller or the master control computer sends out signals of the burst control entering signal ia or exiting signal ib. The exiting of tire burst control of vehicle has a specific function and significance for the state tire pressure determined by this method; it make abnormal state for vehicle control become integrate under normal and burst conditions, so that, the tire burst control does not depend on fetters of tire pressure detected by tire pressure sensor.
(2). Transformation of tire burst control and control mode. Based on these definition of tire burst and tire burst judgment, the method provides a wide operating environment, time and space to the division of normal tire pressure, low tire pressure and tire burst interval, to the tire burst pattern recognition, control and control mode conversion between normal working conditions and tire burst working conditions. With the conversion of various tire blow out control and control mode, there is a very necessary and valuable control overlap between normal and blow out conditions. All kinds of tire burst control and the conversion of tire burst control mode provide a practical, operable and realizing method to control the double instability of vehicle caused by normal control under the condition of tire burst and tire burst.
i. Based on state process of tire burst, the method adopts a tire burst control mode and model corresponding to the process of tire burst. The conversions of tire burst control and control mode is an indispensable and important link for tire burst control. The conversion of control and control modes of vehicle includes the following four levels. First, for level of vehicle. The conversion of control mode between normal condition and tire burst condition of vehicle is an entering and exiting of tire burst control of vehicle in essence. The controller set by driven by man or undriven by man vehicle takes the tire burst control entering or exiting signals ia ib as switching signals of control and control mode conversion, the control and control mode conversion between normal and tire burst conditions of the vehicle are carried out. Under normal and tire burst conditions, the conversion of control mode covers various forms determined by the control modes of braking, steering and driving at next control level of the vehicle. Second, for local level of vehicle. It includes tire burst control for braking and steering, or/and suspension. In state process of tire burst control, tire burst control of vehicle adopts a conversion mode which adapts to control characteristics of braking, steering or/and suspension, according to change of vehicle state process. Third, for coordinated control level of tire burst to vehicle braking, steering or/and suspension. It includes the coordinated controls and control mode conversions of tire burst braking, steering or/and suspension. Fourth, conversion of other control mode and other control types associated with vehicle braking and steering tire burst control. According to coordinating regulations and procedures of control mode, these converting are realized, which include conversions of coordinated control for vehicle braking and throttle or fuel injection, conversions of coordinated control for braking and fuel power driving or electric driving of vehicle, conversions of coordinated controls for tire burst steering rotation force and rotation angle of directive wheel. Fifth, According to the starting point, transition point and critical point of tire burst state of wheel and vehicle, the tire burst state process and control process are divided into several state control periods or stages. The control period and its logical cycle are set based on the parameters and types of tire burst control. The upper and lower level control periods of tire burst are set. Superior control period includes early stage of control of burst tire, control time of real burst tire, control time of tire burst inflection point and control time of separation for rim and tire. In superior control periods, the control mode conversion is realized by converting signals including ia
ib
ic and id. The lower level control period include control cycle of periods of parameters and control types for tire burst, the control mode conversion is realized by converting signals ia(ia1
ia2
ia3 . . . )
ib(ib1
ib2
ib3 . . . )
ic(ic1
ic2
ic3 . . . )
id(id1
id2
id3 . . . ). The conversion of each control cycle and the logical circulating of control periods for stages are realized on the control mode. The conversion signals of tire burst control and control mode are called as tire burst signal I. Based on different periods and logical circulating for tire burst and tire burst control, the control mode, model and algorithm for tire burst adapted to condition of vehicle tire burst are adopted by the controller. The control of tire burst is more precise and can meet the requirement of drastic change of tire burst state by conversion of control mode and model in each control periods and logical circulating of control periods.
ii. Conversion way or type of tire burst control and control mode
Conversions of different control modes and structures which include program, protocol and external converter are adopted by controller.
First, the program conversion mode. A same electronic control unit is set up by tire burst controller and corresponding on-board system. The electronic control unit takes the burst tire signal I as the conversion signal of control and control mode, and calls conversion subroutine of control mode stored in the electronic control unit, to realize automatically conversion of control and control modes, to realize entering and exiting of tire burst control, to realize automatically conversion of non burst tire and burst tire, to realize automatically conversion of control periods or stages of control parameters and modes and of each control periods and logical circulating of control periods. Second, protocol conversion. The electronic control unit set by the tire burst controller and the electronic control units of the vehicle control system are set up independently; the communication interface and protocol between the two electronic control units are set up. According to the communication protocol, the electronic control units uses signals I of tire burst, signals of related control models of sub-system and signals of the control types in each control logic cycle and periods as the conversion signal, to realize entering and exiting of tire burst control and the conversion of the above control and control modes. Third, conversion of external converter of electronic control units. When electronic control unit set by tire burst controller and the electronic control unit of the on-board system are set up independently, and there is no communication protocol between the two electronic control units, entering and exiting of tire burst control and the conversion of the above control modes between the two electronic control units are realized by the external converters which include front or rear converters set. A front converter is set in front position of the two electronic control unit. The measured signals of each sensor and tire burst signal I are input into front converter. When the tire burst signal I arrives, the front converter takes signals including tire burst signals I and conversion signals of the above control modes as the switching signal; the output state of signal of power supply or/and each electronic control unit is changed by control to input signals state of power supply or/and each electronic control unit, to realize the entering or exiting of tire burst control and the conversion of the above control and control modes of the two electronic control unit. A postposition converter is set in rear position of the two electronic control unit of tire burst controllers and the vehicle-control system; the output signal of the electronic control units of the vehicle-board control system and tire burst control system pass through the postposition converter, then, enters the corresponding execution device of vehicle-mounted control system. When tire burst signal I arrives, the output states of signal for the two electronic control unit are transformed by the signal I, to realize entering or exiting of tire burst control and the conversion of the above control and control modes of the two electronic control. The signals input state of electronic control unit refers to the two states where the electronic control unit have or does not have input of signals. Changing of the input state of the signals is a convert from input state of existing signals into input state of non signals, a convert from input state of non signals into the input state of existing signals. Similarly, signals output state of electronic control unit refers to state where the electronic control units have or do not have signal output. Changing of the output state of the signals is a convert from output state of the existing signals into the output state of the non-signal, or convert from output state of non-signals into the output state of existing signals.
iii. Conversion and converter of tire burst control mode of driverless vehicle.
Under the condition of which tire burst of vehicle is determined by central controller of driverless vehicle, the subroutine of control mode conversion set by master control computer is called based on the main programs of active driving, steering, braking, lane keeping, path tracking, collision avoidance, path selection and parking, to realize automatically the conversion of entering and exiting of tire burst control and the conversion of the above control and control modes, and each control cycle and logical circulating of control periods for stages.
(3). Division of tire burst status and tire burst control period or stage
The division of period or stage is based on the specific points of tire burst. A delimitation way or mode of characteristic parameters of tire burst and its joint control period or stage are adopted. After each control period or stage are delimited, the master controller outputs corresponding control signals to each control period. During each control period or stage of tire burst, the same or different tire burst control modes and models are adopted.
i. Delimiting mode of control period or stage based on specific point positions of tire burst. First, start point, sharp change point of tire burst state which include zero of tire pressure, rim separation point, wheel speed, angle acceleration and deceleration of wheel and transition point of tire burst control are determined. Real starting point of tire burst is determined by mathematical model of detecting tire pressure or state tire pressure and its change rate. The inflection point of tire burst control and control parameters, which includes the change point, singularity point of wheel angle acceleration and deceleration speed, and change point of braking force in braking process. Second. Based on tire burst state, the specific time and state point of the tire burst control, the period of tire burst control or stage of tire burst control is determined. The control periods includes early period of tire burst, period of real tire burst, period of inflection point of tire burst and separation period of rim and tire. Early period of tire burst: the period from control starting point set by controller of the tire burst to the real tire burst starting point. Real tire burst Period: the period from the real starting point of tire burst to inflection point of tire burst. The control period of tire burst inflection point: the period from the Inflection point of tire burst to the separation point of tire and rim. The inflection point of tire burst is determined by mathematical model of detecting tire pressure or state tire pressure and its change rate. In period of tire burst inflection point, the change of state parameters of wheel and vehicle is close to a critical point. Control period of separation point of tire and rim: the state and control period after the separation of tire rim, in which the detecting tire pressure and change rate are 0, and the wheel adhesion coefficient changes rapidly. Control period of separation point of tire and rim can be determined by mathematical model of modeling parameters which include vehicle lateral acceleration and wheel lateral deflection angle.
ii. Delimiting mode of control period of tire burst characteristic parameters. Based on tire burst status, tire burst control structure and type, the corresponding parameters in tire burst characteristic parameter set X are select, and the points of numerical of several stages in this parameter set X are set. Each point is set as the dividing point of tire burst status and tire burst control period. The tire burst status period, tire burst control period are constituted by regions in any two point. The burst status demarcated by the periods is basically same or equivalent to the real burst state process in that control period.
iii. Delimiting mode for the control period based on the combination of specific points and characteristic parameters of tire burst. Classification control system of upper and lower levels is adopted in the delimiting mode. The upper level control period can adopt one or more control periods, or it includes early control periods (stages) of tire burst, period of real tire burst, period of Inflection point of tire burst, separation period of tire and rim. The lower level control period: in each control period determined by the upper level, a numbers of series of numerical point positions is set, according to the control period of tire burst control parameters or the value of tire burst characteristic parameters set X; the tire burst status period and tire burst control period are constituted by regions in any two point of lower level control. The control periods of the lower level are set in numerical points
iv. Tire burs and control period of tire burs. First, the previous period of tire burst: the control period usually occurs in the low and medium decompression rate state of tire pressure. According to the actual state process of tire pressure, the vehicle will either enters the real tire burst period to control or exits the tire blow out control. Second, the real tire burst period: In the sampling period of detection tire pressure, the tire pressure variation value Δpr is determined by a function model with modeling parameters pr, {dot over (p)}r:
Δpr=f((pr0−pr),{dot over (p)}r)
When PID is adopted
Δpr=k1(pr0−pr)+k2{dot over (p)}r+k3∫t
Where pr0 is the standard tire pressure, t1, t2 is the sampling period time of detection tire pressure. According to the threshold model, the real tire burst period is determined, when the tire pressure change value Δpr reaches the set threshold value aP1. the ECU outputs the real tire burst control signal, tire burst control enters. Third, the tire burst inflection point period, variety of judgment methods are used. The first method is based on detecting tire pressure of sensor; when detecting tire pressure value is 0 and the equivalent or nonequivalent relative angle acceleration and deceleration velocity e({dot over (ω)}e) or slip ratio velocity e (se) of two wheels of tire burst balance wheelset reaches set threshold value aP2, it is determined to tire burst inflection point. The second method: in the sampling period of detection, a function model is determined by state tire pressure pre and its change value pre:
Δpre=f(pre,{dot over (p)}re)
According to the threshold model, when Δpre reaches the set threshold value aP3 or when the positive and negative sign of equivalent or on equivalent relative angle velocity, angle plus/minus speed and slip rate changes, tire burst inflection point is determined. Fourth, separation period of
tire and rim for tire burst wheel: when steering angle of wheel reaches the threshold value, or equivalent relative side slip angle αi of tire burst balance wheelset, vehicle lateral acceleration ay reaches set threshold value, or when value determined by mathematical model of its parameters reaches set threshold value, separation of tire and rim is judged. Electronic control unit outputs the separation signal of tire and rim for tire burst. The control system of tire burst enters separation period of tire and rim for tire burst wheel.
5). Direction Determination of Tire Burst
Tire burst parameter direction determination is referred to as tire burst direction determination, it is one of the basic conditions to realize the steering control of tire burst vehicle. Based on the determination of the direction of tire burst, the method adopts the steering control of tire burst with independent control characteristics, and it is used in driven by man and driverless vehicles, vehicles of chemical and electric energy driving. First, the direction determination involves the judgement of the direction of the tire burst rotation torque, rotation angle of directive wheels, namely, steering wheels of touching ground, angle and torque of steering wheels and tire burst steering assistant torque. Second, in range of tire burst active steering, direction determination of tire burst includes the direction judgement of steering angle of tire burst wheel, tire burst rotation moment, steering assistant moment or steering driving moment. Third, in range of active steering by drive-by-wire, power steering and drive steering direction determination of tire burst includes the direction judgement of steering driving moment, rotation angle of directive wheels and steering angle of vehicle. All kinds of direction determination mentioned above are referred to as direction judgement of angle and torque. Rotary moment control of tire burst for steering wheel and directive wheels are abbreviated as rotary force control. The determination of tire burst direction is essentially a judgement of direction change for the rotation moment which applies directive wheels by ground. The direction change is caused by the destruction of the wheel structure during vehicle running. When the tire burst control entering the signal ia arrives, the rotating moment control of the tire burst for the directive wheels and the steering wheel starts. The determination of tire burst direction involves setting of specific coordinate system of two kinds of vectors including angle and torque, the calibration of angle and torque direction, the establishment of mathematical logic of direction judgement and configuration of logical combination. Two modes of rotation angle or rotation angle and torque are used to determine the direction. According to different setting of rotation angle and rotation torque, or/and different of parameter detection of sensor, the direction of tire burst adopts the two modes of corner and torque, or angle of tire burst. All kinds of angle and torque parameters to tire burst steering control are vectors. The coordinate system stipulating by this method provides a technical platform for data processing of relevant parameters including power steering, active steering and steering by wire control of driven by man and driverless vehicles. The rotation torque of directive wheels is a rotation moment exerted by ground to directive wheels. The steering assist moment to steering of vehicle is a steering assist or resistance moment inputted by the steering system.
(1). Rotation angle and rotation torque mode
In steering system of vehicle, two kinds of vector coordinate systems of angle and torque are established. The coordinate systems to vehicle include absolute coordinate system set in vehicle and relative coordinate system set in steering axis. The origin of coordinate and direction of rotation angle and rotation torque are set up. Direction determination of rotation angle and rotation torque: under of condition that origin of coordinate is as 0 point, it is determined to direction of left-handed and right-handed for angle and rotation torque in coordinate system, the direction of forward travel (+) and return travel (+) for angle and rotation torque in coordinate system, direction of angle and rotation torque increment or decrement of rotation angle and rotation torque. Establishment and calibration of coordinate system. First, Within range of any rotation angle and rotation direction in absolute coordinate system, a relative vector coordinate system for value and direction of angle and torque are established by standard of torque coordinate system and angle coordinate system. In each coordinate system of angle and torque, a direction calibration mode to rotation direction, direction of positive (+) route and negative (−) route of angle and torque, direction of increment and decrease of angle and torque are used. Second, relative coordinate system includes rotation angle and rotation torque coordinate system of steering wheel or/and directive wheel. Angle and torque of the steering wheel or/and directive wheel adopts two rotation ways for left-handed and right-handed, forward route and return route to the origin. The direction of rotation angle and rotation torque of steering wheel or/and directive steering wheel are characterized by positive (+) and negative (−) of mathematical symbols, from this, the judging direction of steering wheel or/and directive steering wheel are established by the logic combination of mathematics symbols (+), (−) and the judgment logic of its combination. The combination of mathematical logic, positive (+) and negative (−) of mathematical symbols and their changes can indicate the direction determination of all kinds of rotation angles and rotation torque of steering system under normal and tire burst working conditions.
(2). Rotation angle mode. Two kinds of angle coordinate systems which includes the absolute coordinate system set on the vehicle and the relative coordinate system set on the turning axis of the steering system are set up. Establishment and calibration of coordinate system: two or more relative coordinate systems are established in an absolute rotation angle coordinate system, to calibrate the magnitude and direction of the rotation angle. The calibration methods of direction for rotation angle: it can be adopted that rotation direction of left-handed and right-handed to rotation angle, the direction of forward route or return route to the origin, the direction of increment or decrement to rotation angle, in each coordinate system of the rotation angle. The coordinate systems includes the rotation angle and rotation torque coordinate system of the steering wheel or/and the directive wheel. In the process of tire burst of vehicle, the direction determination of rotation torque and rotation angle, the tire burst rotation torque and steering assistant moment of steering wheel or/and directive wheel are determined according to a special defined coordinate system and a combination of calibration for parameters directions. The coordinate systems constitutes as basis of moment measurement and direction determination of active steering driving device. Determination mode of steering wheel angle: rotation angle modes are used. It is established that more relative angle coordinate systems set on absolute coordinate system of vehicle and set on the transfer shaft of the steering system. The direction of rotation angle of steering wheel or/and directive wheel, and direction of their changes of increment and decrement are characterized by positive (+) and negative (−) of mathematical symbols, from this, the judging direction of steering wheel or/and directive wheel are established by the logic combination of mathematics symbols (+), (−) and the judgment logic of their combination. The combination of mathematical logic includes: first, the combination of mathematical logic, positive (+) and negative (−) of mathematical symbols and their changes can be used for direction judgement of all kinds of rotation angles and rotation torque of steering system under normal and tire burst working conditions. Second, the combination of positive and negative (−) of mathematical symbols and their changes can be used for the direction determination of all kinds of angle and torque under tire burst working condition. The direction determination of steering wheel or/and directive wheel system can also be applied for direction judgement in changing caused by structure damage of vehicle running system and serious deformation of ground.
6). Information Communication and Data Transmission
Information communication and data transmission. Under normal and tire burst environments can be used by vehicles of chemical or electric driving, and driven by man and driverless vehicles. Vehicle data network bus is a local area network. In the local area network, topological structure of Controller Area Network (CAN) is bus type. Data, address and control bus are set up. Bus of CPU, local area, system and communication are set up. When tire burst control system and subsystem of vehicle are designed by non-integration, it is adopted that vehicle local area network bus which includes CAN bus, Local Internet Connection Network (LIN) bus. Local Internet Connection Network (LIN) bus is used for distributed electric control system of vehicle, such as digital communication systems of tire burst controller, intelligent sensor and actuator. According to the structure and type of tire burst control system, the on-board network bus of the system adopts fault detection bus, safety and new X-by-wire bus which includes line controlled power steering, active steering (Steer-by-wire), brake-by-wire control (Brake-by-wire) of electronically hydraulic or electronically machinery and engine throttle and fuel injection (Throttle-by-wire) under normal and tire burst conditions. The traditional mechanical system is transformed into an electronic control system managed by high-performance CPU and connected by a high-speed fault-tolerant bus. Especially for the characteristics of the high frequency control of tire burst braking and steering, the conversion of high dynamic control mode and high dynamic response, the control system of tire burst electric control or wire-controlled braking, the tire burst wire-controlled steering and the tire burst throttle telex control are constituted to suit and meet the special environment and conditions of tire burst. The data transmission and communication of information for tire burst control system that include tire burst and no tire burst information unit, the main controller, controller and the execution unit are realized by vehicle network bust, vehicle network of traffic, physical wiring for integration design system.
7). Distance Detection Between Two Vehicles and Environment Identification
Environment identification of vehicle includes detection of distance between the tire burst vehicle and the surrounding vehicle, and environment recognition of driven by man and driverless vehicle. In distance of effective and limited running and space range of anti-collision for tire burst control, the effective control of the motion state, path tracking and collision-proof of tire-burst vehicle can be realized by detecting the distance between the tire burst vehicle and peripheral vehicles, and by identifying to peripheral objects. Tire burst vehicle and peripheral vehicles each other can exchange traffic information by means of tire-burst warning of sound and light emitted by tire-burst vehicle, or by means of vehicle network for traffic, mobile communication and exchange of traffic communication information. The tire burst vehicle can inform surrounding vehicles to avoid actively the tire-burst vehicle by control of their vehicle. In this way, peripheral vehicles can reserve a larger running distance and effective anti-collision space for the tire-burst vehicle under possible conditions of road.
(1). Distance detection between two vehicles is used for driven by man or Vehicle distance driverless vehicles.
i. detection mode of electromagnetic radar, laser radar and ultrasound. Based on the emission, reflection and state characteristics of physical waves, a mathematical model is established to determine the distance Lti and relative speed uc between front vehicles and rear vehicles, or/and the time zone tai of collision avoidance. The parameter Lti uc and tai are a basic parameter of anti-collision control of brake and drive for tire burst vehicle. First, radar distance monitoring. Electromagnetic radar including millimeter wave beams may be used. Wave beam are transmitted by antenna. The reflected echo is received, and is input receiving module, and it is processed by mixing and amplifying. Based on beat and frequency difference signals and vehicle speed signals, the distance between front and rear vehicles, and their relative speed uc are determined by processing module. The time zone tai is calculated by mathematical formula with modeling parameters of Lti and uc. The tai can be determined by ratio of the parameters Lti, and uc. Second, ultrasound distance measurement. The detection adopts a coordinated control mode of ultrasonic ranging and self-adaptive tire burst control for front and rear vehicles. Setting detection distance of ultrasonic ranging sensor, the braking distance and relative speed between the vehicle and the rear vehicle are not limited by control of the tire-burst vehicle in safe distance. Beyond the safe distance between the vehicle and front or rear vehicle, the rear vehicle enters detection distance of ultrasonic ranging sensor of the vehicle, the distance between the tire-burst vehicle and the rear vehicle is controlled by the tire-burst vehicle according to the driver's preview model and the distance control model to rear vehicle. When the rear vehicle enters the range of the ultrasonic monitoring distance of the tire-burst vehicle, the ultrasonic distance monitor of the tire-burst vehicle enters a effective working state. According to the receiving program, the ultrasonic distance monitor of the tire-burst vehicle determines pointing angle of ultrasonic beam, and uses the combination of multiple ultrasonic sensors and specific ultrasonic triggers, to obtain detection signal. The data of signal detected by each sensor is processed. The distance tai between front and rear vehicles, and the relative speed uc are determined. The dangerous time zone tai is calculated. The coordinated control of collision prevention of front and rear vehicles is carried out according to time zone tai.
ii. Machine vision distance monitoring. Vehicle distance monitoring uses common or/and infrared machine vision which include monocular or multi-eye vision, color image and stereo vision detection. A mode, models and algorithms for simulating human eyes are established. Based on color image graying, image binaryzation, edge detection, image smoothing, Open CV digital image processing of morphological operation and region growth, and vehicle detection method (Adoboost) on the basis of shadow feature, the distance measurement is realized by model and algorithm of vision ranging of computer and Open CV of camera. The characteristic signal is extract quickly by the images, and the vehicle distance from the camera sensor to other vehicle is determined by a certain algorithm of visual information processing in real time. The relative vehicle speed uc is determined by parameters and its change of the vehicle speed, acceleration and deceleration speed, relative distance Lt of vehicles.
iii. Vehicles information commutation way (VICW). An interactive distance monitoring method of vehicle is used for transmitting and receiving of data by radio frequency transceiver. Geodetic longitude and latitude coordinates can be obtained by multi-mode compatible positioning. The method use Radio Frequency Identification (RFID) technology. The distance from the satellite to the vehicle receiving device is obtained by positioning of GPS. The equation is formed by more than three satellite signals and the distance formula in three-dimensional coordinates, to solve three-dimensional coordinates X, Y and Z of the vehicle position. The longitude and latitude information is defined on format. The longitude and latitude of the vehicle are measured by ranging model, to obtain location information of vehicle calibrated by the geodetic coordinate calibration. The identified object is identified actively by space coupling of radio frequency signal RFID, coupling of inductance or electromagnetic signal, and transmission characteristics of signal reflection. The radio frequency transceiver module sent all kinds of information about the precise position of the vehicle and the surrounding vehicles, and receives information about status changing of surrounding vehicles, so as to realize the mutual communication between the vehicles. Data processing module of the monitoring system obtains the intercommunication information of surrounding vehicles. Using corresponding model and algorithm, the data processing module of the monitoring system (VICW) can process dynamically the longitude and latitude position data of the vehicle and the surrounding vehicles at real-time. The data processing module can obtain the vehicle moving distance indicated by latitude and longitude degree coordinate based on positioning of satellite within scanning period T of latitude and longitude, to determine speed of vehicles, distance between the front vehicle and back vehicle and relative speed of vehicles. The latitude and longitude coordinate variations of the vehicle position in same direction and opposite direction is determined by judgment model of same direction and opposite direction of the vehicle. The running direction of the vehicle is judged by the longitude and latitude information matrix of vehicle at multiple time, to obtain relative running direction of the vehicle and surrounding vehicles, and orientation of surrounding vehicles which is located in front and rear of the vehicle. According to the longitude and latitude coordinate and their change value of the front and rear vehicles that run same direction, the distance Lti and relative speed uci between two vehicles are calculated by the model and algorithm of measured distance and measured speed for vehicle. Display and alarm module: the module displays information about detected distance between the vehicle and other vehicle in real-time, and output signal of the distance Lti and relative speed uc between two vehicles and front vehicle or rear vehicle in real-time. Display and alarm module display detection distance information of between two vehicles in real time. Audible and visual alarming are realized by buzzer and LED. A threshold model is set by modeling parameters including distance Lti from the vehicle to the front and rear vehicle and the anti-collision time zone tai. When tai reaches set threshold value, the anti-collision signal ih is sent out. The signal ih is divided into two routes, one way of signal ih enters acousto-optic alarm device, and other way of signal ih is put in data bus CAN of vehicle. The tire burst controllers that include main control, braking and driving controller obtains detection signals of relevant parameters Lti, uc, tai and ih from data bus CAN in real-time.
(2). Environmental recognition. Environmental recognition which include recognition of road traffic state, object locating, location distribution of objects and locating distance of objects is used for driverless vehicle. The one of following identification methods or their combination is set.
i. Radar, Laser radar or ultrasonic ranging.
ii. Machine vision, positioning and ranging. The ordinary optical machines and infrared machines are used for distance detection of machine vision. The detection mode of monocular, multi-visual, color image and stereo vision are used. The feature signals are extracted quickly from captured images, and information processing of vision, image and video is completed by certain models and algorithms. The location and distribution of road, vehicles, obstacles and traffic conditions are determined to realize locating and navigation of vehicle, target recognition and path tracking of vehicle. Locating, navigation and path tracking of vehicle of driverless vehicle are determined by structuring and matching of satellite positioning, inertial navigation, electronic map, real-time map, dead reckoning, road state and running state of vehicle.
iii. Intelligent vehicle network of road traffic (IVNRT) is constructed. Road traffic information, surrounding environment information of vehicle, condition and information of running state among running vehicles are acquired and released by IVNRT, to realize communication among the vehicles and surrounding vehicles. A controller of IVNRT and a networked controller of vehicle are set up. Based on structure of intelligent vehicle network, the network and networked vehicles can communicate each other by wireless digital transmission and data processing module set by controller. Networked control of vehicle includes vehicle-borne wireless digital transmission and data processing control. It is set Submodules of digital receiving and transmitting, machine vision positioning and ranging, mobile communication, global satellite positioning navigation and navigation systems, wireless digital transmission and processing, environment and traffic data processing. Under normal and tire burst conditions, networked vehicles can realize wireless digital transmission and information exchange by intelligent vehicle network. Based on intelligent vehicle network and global positioning system, the lane line and orientation of vehicle, driving and running state of the vehicle, path tracking of the vehicle, the distance from the vehicle to other vehicles and obstacles, running states of the vehicle, front vehicle and rear vehicle of the central control system of driverless vehicle can be determined by means of geodetic coordinates, view coordinates and positioning map. These state information of the vehicle and peripheral vehicle include vehicle speed, relative vehicle speed, vehicle structure, driving or braking status of vehicle, tire burst and non-tire burst status of vehicle, tire burst control status, path tracking of the vehicle. First, for networked vehicles, the digital transmission module set by networked controller can obtain relevant datum of structural, running state parameter of the vehicle from the main controller of the driverless vehicle or driven by man vehicle, which includes the datum of state and control parameter of tire burst and process parameter of tire burst. These datum are processed by data processing module and are transmitted by data transmission module. The digital information of tire blowout vehicle is transmitted by mobile communication chip of data transmission module of the intelligent road traffic network. The relevant datum of tire burst vehicle are processed by intelligent vehicle network (IVNRT), then it are released to the surrounding networked vehicles by the network data module of IVNRT. Second. For networked vehicles, the digital transmission module set by controller receives traffic information of passing road by means of the network of networked vehicle, which includes information of traffic lights, signs and road condition, information of location, running status and control status of surrounding networked vehicles, related information of tire burst and tire burst control of vehicles, information of driving status, variation value of parameters and datum, during each detection and control cycle of tire burst vehicle. Third. The wireless digital transmission module set by controller of intelligent vehicle network of road traffic (IVNRT) may accept the request of information inquiry and navigation of vehicles. These request of information inquiry and navigation is processed by the data processing module of IVNRT, then it is fed back to the vehicle of making the request. Fourth, data transmission module set by networked vehicle can query relevant information of other networked vehicle passing through surrounding road with the wireless digital transmission module, so as to realize the wireless digital transmission and information exchange between the vehicle and vehicles of passing through the surrounding road, which include the running environment, road traffic and driving status information of vehicles.
8). Vehicle Tire Burst Control by Manual Key
Vehicle tire burst control use tire burst control by manual key. The control key adopts mode of multiple key position or/and many times key control in a certain period to determine set type of manual key position. The control key includes knob key and press key. Two key positions of “standby” and “off” of control key are set. Assigning values to the logic states Ug and Uf of the two key positions, the high and low level or the number can be used as identification of Ug and Uf. The master controller or the electronic control unit set by master controller can identify logic state, change of the logic or change of opening and closing of the two key position by data bus. When the key position of “standby” and “closing” changes, the logic state signals ig and if are output. When vehicle control system is exerted by electricity, the tire burst controller of the system is reset or cleared to 0. The logic state of the RCC control key position Ug and Uf is determined by key position of “standby” or “off” of control key. When the key position is in the “off” state, the display lamp set in background of the key position will be on, until the manual operation of the knob or the key is implemented, to transfer it to the “standby” state of key position, thus the background display lamp will be off. During vehicle running, control key of RCC shall always be placed in the key position of “standby”. The mutual transfer of the two key positions is a compatibility control between active control of tire burst of the system and manual key operation control. The control logic of the manual key operation is taken as priority, and it covers the active control logic of the tire burst controller of the system.
9). Tire Burst Master Control Program or Software
(1). Computer control program or software.
According to tire burst control mode, model and algorithm, control structure, process and function, program language is used to programming. Datum are loaded. Analyzing and testing operation performance of programs, tire burst control main program and subprogram of brake, drive, steering, suspension, or/and path planning and path tracking of vehicle are prepared. Using programming by structuration, the program is constructed by three basic control structures which include sequence, condition and cycle. Program modular is formed by programing modularization, structured programming, planning and designing model. Defining functions and similar functions that are assembled in a single module. The program modular tested is integrated with other modular to form whole program organization of tire burst control. The program modules include tire burst control structure and function module.
(2). Master control program or software for tire burst of vehicle. According to control structure and process of tire burst master controller, a mode, model and algorithm of tire burst master control, a structured program design is adopted, to form tire burst master control programs or software which include program modules of tire burst information collecting and processing, parameters calculation, tire burst mode identification, tire burst judgment, tire burst control entering and exiting of tire burst control, control mode conversion, distance detection and environment identification, information communication and data transmission, tire burst direction determination, manual operation control, or/and networking control procedure of vehicle.
1). Tire Burst Brake Control and Controller
This method adopts the tire burst brake control with independent control characteristics. The tire burst brake covers chemical energy driven and electric driven vehicles, driven by man and driverless vehicles. The method set up tire burst brake control and controller.
(1). Control parameters and control variables of braking in process of vehicle tire burst. Under normal working conditions, the brake controller mainly provides balanced braking force to the whole vehicle. Therefore, the braking force Qi for each wheel is acted as control variable, and the motion state of the vehicle is regulated by the braking force Qi. Under the condition of tire burst, the control characteristic of vehicle changes. Based on unstable state of the vehicle, the tire burst brake controller regulates instability of the vehicle by means of differential braking to wheelset. Based on the purpose of tire burst braking control, tire burst braking controller uses parameters of wheel angle deceleration {dot over (ω)}i and slip rate Si as control variables, and adjust braking force Qi of each wheel by using parameters of deceleration {dot over (ω)}i and slip rate Si, to control directly vehicle instability by changing of wheel state characteristics which is indicated by {dot over (ω)}i or Si. The {dot over (ω)}i and Si used for control variables is determined by the unbalanced braking control characteristics of tire burst stability control. Using {dot over (ω)}i and Si as control variables, the transfer chain of braking control is simplified, the dynamic response characteristic of braking of vehicle is improved, the transfer chain of braking control is shortened, the hysteretic response time of the whole vehicle state to braking wheel is reduced; the effect and influence of structural parameters of braking actuator to braking control characteristics are balanced or eliminated. In view of this, the wheel braking force sensor set in the braking actuator may not be adopted.
(2). Braking control mode and type
i. The determination of braking control period Hh for tire burst. According to state process of tire burst, requirement of braking control characteristic and response characteristic of braking actuator to control signal, the braking control period Hh is determined. The Hh is consistent with change of tire burst state process, and adapts to the control requirements of extreme change of tire burst state process, and meets the requirements of frequency response characteristics of electronically controlled hydraulic brake device or electronically controlled mechanical brake device. The Hh is a value set by controller, or is a dynamic value set by controller. The dynamic value of Hh is determined by mathematical model with the state parameters of wheel and vehicle. The mathematical mode of Hh include the Hh can be a function of tire pressure and its change rate. According to the requirements of anti-collision control for vehicle, the anti-collision control period Ht for vehicle is set. The values of Hh and Ht are the same or different. The braking control period Hh can be as period of logic cycle of braking control combination. Based on tire burst state, control stage and time zones tai of anti-collision control for tire burst vehicle, the corresponding logic cycle of braking control combination is implemented based on the control cycle Hh. A mode or type of wheel steady braking A control, vehicle steady state C control, balanced braking B control of each wheel and total braking force D control of all wheel are adopted by related modeling parameter. These control mode is referred as braking A, B, C and D control modes. In each braking control period Hh, a group of braking A, C, B or D control and its logic cycle of combination control are executed. In each logic cycle of Hh, a control combination can be repeated, or can also be converted into another a control combination.
ii. Brake A. B, C, D independent control or its logical combination control. Based on vehicle motion equation of one or more freedom, vehicle longitudinal and lateral mechanics equation, vehicle yaw moment equation and wheel rotation equation, and tire model of wheel, it include:
Σt=14Fxi=m{dot over (u)}xM=Σl=14FxiL
Fxi=f(Si,Nzi,μi,Ri)
Ji{dot over (ω)}iFxiRi−Qi
A relationship model between braking force Qi and state parameters of angle acceleration, deceleration {dot over (ω)}t, slip rate Si of each wheel is established. The quantitative relationship between the control variables Qi and other control variables {dot over (ω)}i and Si is determined, to realize the conversion of the control variables from Qi to {dot over (ω)}i or/and Si. The Fxi {dot over (u)}x
L and Ji in the formulas is respectively wheel force exerted by the ground, the longitudinal acceleration of the vehicle, the distance from the wheel to mass center via longitudinal axis and the moment inertia of vehicle. In the independent control of A, B, C and D, or/and the control of their logical combination, the mathematical models of the relationship between one of control variables Si and parameters including αi
Nzi
μi
Gri Ri are established under action of braking force Qi of each wheel. The models include:
{dot over (ω)}i=f(Qi,αi,Nzi,μi,Ri)
S
i
=f(Qi,αi,Nzi,μi,Gri,Ri)
In the formulas, the αi, Nzi, μi, Gri and Ri is respectively sideslip angle, load, friction coefficient, stiffness of wheel and effective rotation radius of wheel. Other letters have same meaning as those mentioned above. Based on vehicle motion equation of one or more freedom, vehicle longitudinal and lateral mechanics equation, vehicle yaw moment equation, wheel rotation equation and tire model of wheel, the logic combination of brake A, C, B or/and D control model are determined, according to state process of wheel tire burst and wheel stability, vehicle stability and vehicle attitude, or/and real-time change point and change value of relating parameters. Under certain state conditions of tire burst, the combination rules of control logic are as follows. Rule 1. The logic relationship of logical sum to two kinds of control model or type. The logic relationship is represented by sign “∪”. For example, BUC denotes simultaneous execution to two control types which include braking B and C control. BUC is algebraic sum of two control values B and C. The rule of logic combination is unconditional logic combination. If there is not substitution of other control logic, the logic control state will be maintained. Rule 2. The logic relationship of substitution and control conflict each other between two kinds of control model or type. The logical combination based on the rules is conditional logic combination. The logic relationship of substitution is represented by the logical symbol “⊂”. The right side control model or type can be replaced by the left side control model. The one of conditions is that control model or type on the right side takes precedence. For example, A⊂B denotes that B can be replaced by A under certain conditions. Namely, the left side control model or type can cove the control model or type of right side. The A⊂C logic for a wheel control is expressed as follows: first, C control is executed, and then A control is executed. When the control condition of A is reached, C control is changed to A control, or A control replaces C control. According to change point of normal condition, tire burst condition and control periods, or when the change value of brake control reaches a certain condition or threshold value, the substitution or conversion of logic combination control is realized or is completed at real-time. Rule 3. The logical relation of conditional sequential execution of each logic and logic combination. The logical relation is expressed by sign “←”. Whether the right side control is completed or not, when the set conditions are met, the left side control or control logic combination is executed on the direction of arrow. The symbol “←” expresses conditional control execution order of the upper and lower or equal logical relation. In upper and lower position logical relations, the logical combination of A, C, or/and B control is represented by symbol (E), the control form includes D←(E). The D←(E) indicates that D control can be implemented only under certain conditions of which logical combination of (E), namely logical combination of A control and C control has be completed. The one of representations of allelic logical relations includes N←(B); the N represents A control, C control and their combination control types in allelic logical relations. For example, control logic combination B←A∪C shows that B control can be executed only when certain conditions are reached, regardless of whether A∪C has been executed or not. The logic combination stipulates that the control quantity of unselected control type is 0. The form of logic combination include a single control type of A, C or B, and also includes A∪C C∪A, D←A∪C
D←(E) type or mode. The control logic conversion is realized when the corresponding converting signals of tire burst brake control arrives.
iii. The controlling object of brake A control is all wheels. Brake A control includes anti-lock control of non-burst tire wheel and steady-state control of tire burst wheel. The steady-state of tire burst wheel control adopts two modes of releasing brake force or decreasing brake force of tire burst wheel. In the mode of decreasing brake force, the angle deceleration {dot over (ω)}i or/and slip rate Si are taken as control variables, and braking force Qi is taken as parameter variables. The values of control variable {dot over (ω)}i or/and Si of burst tire wheel are reduced by equal or unequal amount and step by step, until the braking force is relieved. Brake force of burst tire wheel is adjusted indirectly.
iv. The controlling object of brake B control is all wheels. The balance braking forces of each wheel are involved in the longitudinal control (DEB) of wheels. Defining of balanced wheelset: each tire force exited by ground on the two wheel of the wheelset to torque of center mass of vehicle is opposite in direction. Balancing wheelset include burst tire and non-burst tire balancing wheel pairs. Defining concept of balance distribution and control of control variables for brake B control: using angle acceleration and deceleration speed {dot over (ω)}i and slip rate Si of each wheel as control variables, theoretically, the torque sum of each tire force to the center mass of vehicle is zero in the distribution of {dot over (ω)}i and Si of each wheel. The brake B control adopts balancing distribution and control form to two-wheel braking force of wheelset. One of comprehensive control variables {dot over (ω)}b, Sb and Qfc is distributed between two axles by mathematical model with one of state parameters {dot over (ω)}i, Si of two-wheel and load of front and rear axles. The control variables {dot over (ω)}i and Si of two-wheel to front and rear axles are allocated according to the equal or equivalent model. Among them, the values of comprehensive control variables {dot over (ω)}b, Sb and Qfc are determined by average or weighted average algorithm of values of {dot over (ω)}i, Si of each wheel.
v. The control object of tire burst braking C control is all wheels. The braking C control involves a most dangerous and most difficult control to tire burst under running states of straight line and steering of vehicle. The brake C control is based on state process for tire burst. The additional yaw moment Mu produced by unbalanced braking moment of differential braking of wheelset are used for balancing yaw moment Mu of tire burst, to control insufficient or excessive steering of vehicle in tire burst. The distribution of additional yaw moment Mu to wheels adopts the parameter forms of angle deceleration {dot over (ω)}i, slip rate Si or braking force Qi of each wheel. The distribution of additional yaw moment Mu of control variable {dot over (ω)}i and Si have better control characteristics than the characteristics of parameter Qi. The control mode of braking C control is as follows.
First, stability control of tire burst yaw moment and additional yaw moment of vehicle. Longitudinal tire force is generated by differential braking force of each wheel of the vehicle. The additional yaw moment Mu is formed by moment of tire force to vehicle mass center. The tire burst yaw moment Mu′ is balanced with additional yaw moment Mu which can restores stable running state of the vehicle, to realize stability control of vehicle. Brake C control is based on dynamics equations of wheel and vehicle in straight running and steering of vehicle. Under normal and tire burst conditions, the stability control modes, models and algorithms of vehicle are established by modeling parameters which include motion, steering mechanics of wheel and motion state parameters of vehicle; models and ways of theoretical, experimental or empirical modeling are used. Or analytical formulas of mathematics are transformed into state space expressions. Under normal and tire burst conditions, the ideal and actual values of vehicle yaw angle velocity ωr, sideslip angle β, longitudinal deceleration ax or/and lateral acceleration ay of yaw control model for vehicle braking are determined by vehicle model and parameter values of sensor detection. The deviation between the ideal and actual values of the parameters is defined:
e
ω
(t)=ωr1−ωr2eβ(t)=β1−β2
Under condition of tire burst, the additional yaw moment Mu of brake C control takes eω ax
ay as parametric variable. A mathematical model of additional yaw moment Mu for tire burst is established:
M
u(Pra,ux,δ,eω
In the model, the Pra is tire pressure, the ux is vehicle speed, the δ is rotation angle of steering wheel, the e(ωe) and ({dot over (ω)}e) are equivalent relative angle velocity deviation, angle acceleration or deceleration deviation of two wheels of balance wheelset, the ax and ay are longitudinal and lateral acceleration of vehicle and the μi is the friction coefficient. The tire pressure Pra or the equivalent relative slip rate deviation e(Se) can be interchanged with equivalent relative angle deceleration deviation e({dot over (ω)}e). On this basis, the basic formula of the optimal additional yaw moment Mu includes:
M
u
=−k
1(e(ωe),e({dot over (ω)}e))eω
M
u
=−k
1(Pr)eω
In the formula, k1(e(ωe), e({dot over (ω)}e)) or/and k2(e(ωe), e({dot over (ω)}e)), k1(Pr) or/and k2(Pr) are the feedback variables or parameter variables of tire burst state of vehicle, in which e(Se) can be interchanged with e({dot over (ω)}e). In view of the control coupling between the yaw angle speed ωr and the centroid sideslip angle β of vehicle, it is difficult to achieve ideal yaw angle speed ωr and ideal centroid sideslip angle β at the same time. The optimal additional yaw moment Mu can be determined by using control algorithm of modern control theory. One of the algorithms is to design an infinite time state observer based on LQR theory, to determine the optimal additional yaw moment Mu. When equivalent model and algorithm are used, the modified model, model and algorithm of additional yaw moment Mu, which include parameter feedback correction, time lag correction, tire burst impact correction, separation correction of wheel and rim, touchdown correction of rim, clamping correction and tire burst comprehensive modified mode, are adopted.
Second. A vehicle stability control model is established by modeling parameters of yaw angle velocity deviation eω
M
u
=M
ur
+M
n
The direction of Mn and Mur, namely, rotation direction of left or right-handed of vehicle, is represented by mathematical symbols “+” or “−”. When the direction of Mn is same as direction of Mur, the maximum value of Mu is obtained, that is, under condition of additional yaw moment Mur produced by the minimum longitudinal differential braking force, the Mu can balance with the tire burst yaw moment Mu′. Under the combined action of Mur and Mn, the vehicle stability control has a better longitudinal and lateral dynamic characteristics which including slip state and attachment state of wheel, longitudinal and transverse tire force of wheel, yaw characteristics and frequency response characteristics of wheel. When yaw control wheel is efficiency yaw control wheel at the same time, tire burst vehicle can obtain the maximum efficiency yaw moment Mur which can realize the stability control under condition exerted by the minimum differential braking force to two wheels.
Third, distribution of each wheel of additional yaw moment Mu that restores vehicle stability. The vehicle of symmetrical distribution of four wheels is referred to as four-wheeled vehicle. The rotation direction of yaw control wheel, efficiency yaw control wheel and yaw moment Mn can be determined by position of where the tire burst wheel located in the front, rear, left or right of vehicle, and direction of rotation angle of steering wheel, positive or/and negative of yaw angle velocity deviation of vehicle and insufficiency and excessive steering of vehicle. Selection of yaw control wheels. Mode 1: the wheels of which opposite side to tire burst wheel location of vehicle is yaw control wheels. Mode 2: the direction of additional yaw moment Mu can be determined by positive (+) and negative (−) of yaw angle velocity deviation; from this, yaw control wheels can be determined by the direction of the Mu. Mode 3: according to model and definition of efficiency additional yaw moment, and based on direction judgment of yaw moment Mn or judgment of positive and negative value of yaw moment Mn, under condition of which yaw control wheels are exerted same braking force, the wheel that higher value of additional yaw moment Mu can be obtained in yaw control is efficiency yaw control wheel. For vehicle of four-wheel symmetric distribution, the number of yaw control wheels is two; it includes wheels which are located in opposite to side of the tire burst wheel. In the steering process, the outer side wheels of vehicle are yaw control wheel while the inner wheel get tire burst; the inner wheels of vehicle are the yaw control wheels while the outer side wheels get tire burst. The non-yaw control wheel includes one tire burst wheel and one wheel which can produce yaw moment of same direction as the tire burst yaw moment Mu′ under differential braking.
Fourth. Distribution model of the additional yaw moment Mu to wheels adopts single-wheel, two-wheel or three-wheel model. Single wheel model. In straight line running state of vehicle, Muk equals Mu, and Mn equals 0. In two wheels of yaw control, wheel bear by larger load is selected as the efficient yaw control wheel, because the diameter of tire burst wheel reduces and the load of each wheel redistributes for tire burst vehicle. Under the condition of braking of tire burst wheel in process steering, steering and braking control model of vehicle is adopted: Mu=Mur+Mn. Under condition of which direction of Mur and Mn of vehicle is same, the wheel bear by larger load is efficiency yaw control wheel. Two-wheel model. In straight line running state of vehicle, The Muk equals Mu, and the Mn equals 0. The coordinated distribution model of two yaw control wheels is used, to determine distribution ratio of two yaw control wheel. A distribution model with modeling parameters of wheel load and rotation angle of steering wheels is established, according to weight ratio of two wheel loads. Under the condition of tire burst braking in steering, one of the front axle and rear axle is steering axle, and one of two yaw control wheels must be steering wheel. Based on allocation model of additional yaw moment Mu to wheels: Mu=Mur+Mn. Under condition of which direction of additional yaw moment Mu including Mur and Mn is determined, a coordinated distribution model of two yaw control wheels is established by modeling parameters which include Mur and Mn, longitudinal and lateral adhesion coefficient or friction coefficient of braking and steering wheels, the load Mzi and load transfer amount ΔMzi, rotation angle δ of steering wheel or rotation angle θe of directive wheel, Longitudinal brake slip rate Si of two yaw-controlled wheels, side-slip angle of wheels during braking in steering, or lateral adhesion coefficient of wheels. According to a theoretical or empirical model of friction circle, a coordinated distribution model of two yaw control wheels is established by the longitudinal and transverse adhesion coefficient or friction coefficient of wheel during braking and in steering process. Based on the coordinated allocation model, the efficiency yaw control wheels and distribution of additional yaw moment Mu between two yaw control wheels is determined. Based on the braking friction circle model, a series of ideal values or limit values of longitudinal braking slip rate and side slip angle of yaw control wheels are determined by brake slip rate Si, steering wheel angle δ or directive wheel angle θe in steering and braking status process. Under the condition of keeping stable state of vehicle steering and braking wheels, yaw control wheels and distribution of additional yaw moment Mu between yaw control wheels are determined. Three wheel model. The three wheels are composed of two yaw control wheels and one non yaw control wheel. The distribution of additional yaw moment Mu of the two yaw control wheels are modeled according to the above two wheel model. According to the two wheel model, vehicle stability control under the condition of straight and steering of vehicle is realized. When braking force is exerted to no yaw control wheel, additional yaw moment Mu is determined by the sum of the yaw moment vectors of two yaw control wheels and one non yaw control wheel. One yaw control wheel and one non yaw control wheel can form a balanced wheelset, and the distributed braking force of two yaw control wheels of the balance wheelset is equal or unequal. Under brake control state of the straight line running and steering of tire burst vehicle, and when the balanced wheelset is a no tire burst wheelset, whether it is a steering wheelset or not, logic combination of C∪B of B control of balanced braking of wheels and C control of vehicle steady state can be used by the balance wheelset. Under the condition of priority to meet the vehicle stability braking C control, the three wheel model can achieve the maximum braking force and the braking force of the burst braking C control is reduced. In the additional yaw moment Mu generated by the burst braking C control, the additional yaw moment Mb′ for tire burst is balanced by additional yaw moment Mur generated by vehicle longitudinal braking, and it may compensate understeer or oversteer of vehicle by resulting of yaw moment Mn.
vi. Total braking force D control for tire burst. The D control is used to control movement state expressed by deceleration {dot over (u)}x of tire burst vehicle and comprehensive angle deceleration {dot over (ω)}d of wheels. The braking D control uses one of deceleration {dot over (u)}x of vehicle, comprehensive angle deceleration {dot over (ω)}d, comprehensive slip rate Sd and comprehensive braking force of wheel as control variables. The values of {dot over (ω)}d, Sd and Qd are determined by average or weighted average algorithm of {dot over (ω)}i, Si and Qi of each wheel. The D control adopts forward or reverse direction control modes in transferring direction of control variable. In the forward mode, the target control values of {dot over (ω)}d or Sd of each parameter form {dot over (ω)}i, Si for total braking force D control are determined by the vehicle deceleration {dot over (u)}x; one value of the parameters of {dot over (ω)}i Si and Qi is allocated to each wheel, and the control logic combination may adopt (E)←D←{dot over (u)}x. In reverse mode, one of the parameters of angle deceleration {dot over (ω)}i, slip rate Si and braking force Qi is used as control variables, and the target control values or actual values of control values {dot over (ω)}dg or Sdg of {dot over (ω)}i or Si for braking A, B and C control is determined. The control logic combination of {dot over (u)}x←D←(E) is used, where E represents the logical combination of A, B and C control.
(3). Braking control for vehicle tire burst
i. Tire burst braking control adopts hierarchical coordinated control form. The upper level is the coordinated level and the lower level is the control level. The upper level determines control mode, model and logical combination of A, C, B and D control in the each braking control period Hh of logic cycle, as well as transformation rules and period Hh of each logical combination. The lower level of the control completes a sampling of relevant parameter signals of braking A, C, B, D control and their combination control once in each period Hh, and completes datum processing, according to braking A, C, B, D control types and their logical combination, control model and algorithm. In the each braking control period Hh, tire burst controller outputs control signals, to implement once allocation and adjustment of angle deceleration {dot over (ω)}i or slip rate Si of vehicle.
ii. In braking control, tire burst control adopts one of two modes when wheels enter steady-state control A. Mode 1. After completing a braking control mode, model and logic combination of this period Hh, it enters a braking control of a new cycle Hh+1. Mode 2. The braking control in this period Hh is terminated immediately, and it enters a new control cycle Hh+1 at the same time. In a new period, it adopted to control mode and model of anti-lock braking A control for non-burst tire wheels under normal conditions, or it adopted to steady-state braking A control for burst tire wheels under tire burst conditions; the original control logic combination of braking C, B and D control for burst tire wheels can be maintained, or a new control logic combination is adopted.
iii. A control mode, model and control logic combination are used, according to state process of tire burst, real-time change points and change values of the control parameters to wheel stability, vehicle stability, attitude or collision avoidance of vehicle as well as different stages or control times of tire burst braking control, a corresponding control mode, model and control logic combination are adopted. A stable deceleration and stability control of vehicle are achieved by logical cycle of control period Hh. In brake A, C, B and D control independently or its logic combination control, it may be established to relational models between deceleration {dot over (ω)}i and slip rate Si, or between braking force Qi and state parameters {dot over (ω)}i Si of wheel, based on motion equation of multi freedoms for vehicle, longitudinal and lateral mechanical equation of vehicle, yaw control model of vehicle, the rotation equation of wheel and tire burst model. The quantitative relationship between control variables {dot over (ω)}i and Si or between Si and Qi can be determined, to realize conversion of the control variables.
iv. In the braking A, C, B and D independent control of or their logical combination control, if necessary, some relevant mathematical models between control variables including {dot over (ω)}i and Si and parameter variables including αi Nzi
Gri
Ri are established under condition of which wheels are exerted by braking force Qi. The relationship models or its equivalent models is used to determine function and influence of each parameter variable to its control variable. Among them, the αi, Nzi, μi, Gri and Ri are wheel sideslip angle, wheel load, ground friction coefficient, stiffness and effective rotation radius of wheel. In the logic cycle of control period Hh of braking A, C, B and D control, the parameter Δωi is equivalent to the parameter {dot over (ω)}i when the control period Hh is small. A mathematical model and algorithm of tire burst braking control are established by control variables which includes parameters {dot over (u)}x, {dot over (ω)}i and Si. In the logic cycle of control period Hh, the target control values and the allocation values of one of control variables {dot over (u)}x, {dot over (ω)}i and Si are determined by braking A, C, B or D control types and its logic combination in braking A, C, or B control. Where target control value of wheel comprehensive angle deceleration {dot over (ω)}d, comprehensive slip rate Sd in braking D control are determined by target control value of parameter {dot over (ω)}i or Si of braking A, C, or B control of wheels.
(4). The specific control mode adopted in tire burst braking control obviously improves the performance and quality of the control which include various dynamic characteristics, frequency response characteristics, control chain and control effect of the braking control, to adapt Independent braking control or collision avoidance coordinated control for abnormal state of vehicle under normal working, whole state process of control periods of low tire pressure, real tire burst, inflection point of tire burst, separation of tire and rim and. Angle deceleration {dot over (ω)}i, slip rate Si of wheel and speed change rate {dot over (u)}x of vehicle are taken as control variables in process of tire burst braking control. Through logical combination of braking A, C, B and D control types and their logic cycle of period Hh, it is realized to steady state control of wheel, posture and stability control of vehicle which are consistent with the state process of tire burst, and the control objectives of longitudinal and yaw of tire burst vehicle is achieved, under the conditions about which the effective rolling radius, adhesion coefficient and load of tire burst wheel change sharply and deteriorates instantaneously of vehicle motion state. The tire burst braking control uses a control mode coordinated with controls of electronic throttle of engine, fuel injection and tire burst steering, or with output control of electric power vehicle. The tire burst braking control uses a control mode coordinated with steering of vehicle. A brake control of engine idling may be adopted in period from the arriving of tire burst control entering signal ia to starting of tire burst braking control; brake control of engine idling exits according to the set conditions. The tire burst brake control uses many ways of exiting; when the tire burst brake control exit signal ib arrives, the brake control of engine idling exit. For the vehicle driven by man or the driverless vehicle with the auxiliary manual operation interface, the exiting of tire burst brake control is realized by control of driving pedal. For vehicle of driverless vehicle, tire burst brake control exit when central master computer sends out the exiting command of tire burst brake control; tire burst brake control exit according to vehicle anti-collision coordination control requirements.
2). Idling Brake Control, Brake Compatibility Control and Controller for Tire Burst Engine
Braking of tire burst vehicle adopts braking control of engine idle or/and braking compatibility control. Braking control of idle engine can be started-up in control period from early stage of tire burst control to the real burst time. The braking compatibility controls can be used as vehicles driven by man or driverless vehicle with manual assistant braking operation device, the former is referred to braking control of artificial compatibility, and the latter is referred to braking control of automatic compatibility. On the basis of environmental identification of tire burst vehicle, the compatible control of manual braking adopts self-adaptive control mode of tire burst braking. The braking process of tire burs vehicle is characterized by the parameters which include the comprehensive angle deceleration {dot over (ω)}d or comprehensive slip rate Sd of wheels. The tire burst state is characterized by tire burst characteristic parameter γ. The comprehensive angle deceleration {dot over (ω)}d and comprehensive slip rate Sd are determined by average algorithm or weighted average algorithm of parameter {dot over (ω)}i or Si for wheels.
(1). Engine idle brake control and controller
The vehicle set or not set the engine idle brake controller. According to tire burst state process, vehicle with the controller can enter idle brake control of the fuel engine in the early stage of tire burst control, or in any time before the actual tire burst time. The engine idle brake control adopts dynamic mode. In the process of engine idle brake, engine injection quantity of fuel oil is zero, that is, fuel injection quantity of engine is stopped. The idle braking force of engine is determined by model of opening of throttle control. The idle braking force of engine is an increasing function with the opening increment of throttle. A threshold value of engine idle braking is set. When the engine running speed reaches the threshold value, the engine idle braking is stopped. The threshold value is greater than the idling brake set value of engine. Specific exiting modes of brake control of engine is set by following. When the tire burst signal ib arrives, or vehicle enters the collision risk time zone (ta) of vehicle, or yaw angle rate deviation eω
(2). Brake compatibility control of vehicle tire burst. According to separate or parallel operation state of tire burst active brake and pedal brake of vehicle, a compatibility mode of tire burst active brake control and anti-collision coordinated control of vehicle driven by fuel oil engine or electric engine is established, so as to solve the control conflict when the two control kinds of brake are operated in parallel. When two control kinds of the active brake and the pedal brake are operated separately, the two control does not conflict. The brake compatibility controller does not process compatibly to the input parameter signals of each control; output signal of brake control of the brake compatibility controller is not processed compatibly. When the tire burst active brake and the pedal brake, which hereinafter referred to as the two types of brake, are operated in parallel, the target control values of control variable including comprehensive angle deceleration {dot over (ω)}d′ or comprehensive slip rate Sd′ of each wheel are determined by relationship models of {dot over (ω)}d′ and Sw′, Qd′ and Sw′, Sd′ and under certain braking force, among, the Sw′ is displacement of the brake pedal. The deviation eQd(t), e{dot over (ω)}d(t) or eSd(t) between the target control value of active braking force Qd, angle deceleration {dot over (ω)}d or slip rate Sd and their actual values Qd′, {dot over (ω)}d′, Sd′ are defined:
e
Sd(t)=Sd−Sd′,e{dot over (ω)}d(t)={dot over (ω)}d−{dot over (ω)}d′
The control logic of brake compatibility is determined according to the positive (+) and negative (−) of deviation When the deviation is greater than zero, the comprehensive braking force Qda, comprehensive slip rate Sda and comprehensive angle deceleration ωda which are output by the brake compatibility controller are equal to its input values Qd Sd
ωd. When the deviation is less than zero, one of the input parameters Qd′, ωd′, Sd′ is processed by the brake compatibility controller according to brake compatibility control model. A brake compatible function model is established by modeling parameters that include tire burst characteristic parameter γ, active braking force deviation eQd(t), angle deceleration deviation eωd(t) and the slip rate deviation eSd(t) in the positive and negative stroke of the brake pedal of braking system:
S
da
=f(eSd(t),γ){dot over (ω)}da=f(e({dot over (ω)}e),γ)
According to the model, brake compatibility controller processes to input parameter signals, from this, the output value of brake control is the output value processed by brake compatible controller. The modeling structure of the function model for brake compatibility control: the Qda ωda and Sda are respectively increasing function of absolute value increment of deviation eQd(t), e{dot over (ω)}d(t) or eSd(t) in positive stroke, and are respectively decreasing function with absolute value decrement of deviation eQd(t), e{dot over (ω)}d(t) or eSd(t) in negative stroke. The asymmetric brake compatibility model is represented as: in the positive and negative stroke of the brake plate, the model has different structures; the deviation eQd(t), eSd(t), e{dot over (ω)}d(t) and the weight of the tire burst characteristic parameter γ in the positive stroke of the brake pedal is less than those in the negative stroke of the brake pedal, and the function value of the parameter in the positive stroke of the brake pedal is less than those of the parameter in the negative stroke of the brake pedal:
According to the characteristics of the tire burst state, braking control period and anti-collision time zone, a mathematical model of the tire burst characteristic parameter γ used brake compatibility control is established by modeling parameters which include ideal and actual yaw angle velocity deviation eω
γ=f(tai,eω
The modeling structure of the tire burst characteristic parameter γ is determined: the parameter γ is a increasing function of increment to absolute value of eω e(ωe)
e({dot over (ω)}e), and the parameter γ is a increasing function of decrement to parameter tai. The modeling structure of the brake compatibility control: the Qda
ωda and Sda respectively are the decreasing function with increment of γ. Based on the model, self-adaptive coordinated control by man and machine for parallel operating of pedal braking of brake system and the active braking of vehicle tire burst can be determined by the control variables Qda and Sda. After processing of brake compatibility, the control logic of wheel steady-state braking (A), balance braking (B), vehicle steady-state braking (C) and total braking force (D) control and their control logic combination are determined, in which the control logic combination includes A⊂B∪C←D
C⊂B∪A A⊂C←D, C⊂A←D. The brake compatibility controller adopts closed-loop control. When the deviation eQd (t), eSd (t) or e{dot over (ω)}d(t) is negative, the input parameter signals of Qd, Sd, or/and {dot over (ω)}d of brake compatibility controller are processed compatibly by braking compatibility model with brake compatibility deviation eQd(t), eSd(t), e{dot over (ω)}d(t) and parameter γ. After the brake compatibility treatment, the brake force distribution and brake force adjustment of each wheel are carried by the braking B control and braking C control, so that, the actual value of the active brake control for tire burst always tracks its target control value. After the brake compatibility treatment, the output value of active brake control for tire burst is its target control value Qda or Sda, that is, the compatibility control of brake is a control of zero deviation. In early stage of tire burst and anti-collision safety time zone of the vehicle and rear vehicles, the value of parameter γ can be zero, thus the vehicle can adopt brake control logic combination A⊂B∪C. In real tire burst time or/and risk time for safety of anti-collision, brake control logic combination of A⊂C or C⊂A is adopted. Along with deterioration of tire burst state of the vehicle, or when the front vehicle and rear vehicles for tire burst enter the forbidden time zone for anti-collision, the brake control of tire burst wheel will be changed from steady state brake control to release of braking force of tire burst wheel. During logic cycle of period Hh of brake control, except the tire burst wheel, the differential braking force of steady-state brake C control of wheels are increased. By means of the coordination control between the actual value of each control variable Qda
ωda or Sda and the characteristic parameter value γ for vehicle tire burst, the target control value of Qda
ωda or Sda is reduced, until the target control value of control variable Qd′
{dot over (ω)}d′ or Sd′ of the vehicle pedal braking is less than the target control value of control variable Qd
ωd or Sd of the tire burst active brake, to realize a compatible self-adaption control of artificial pedal brake and active brake of tire burst.
(3). Compatible control of active braking and collision avoidance coordinated braking for tire burst of driverless vehicle. Based on environment identification of tire burst vehicle, the compatibility control mode of the active brake and the anti-collision brake of driverless vehicle to tire burst vehicle is established by one of modeling parameters which include total amount of braking force Qd1, comprehensive angle deceleration {dot over (ω)}d1 of wheel and deceleration speed {dot over (u)}x1 of vehicle, and by one of modeling parameters including corresponding total amount of braking force Qd2, comprehensive angle deceleration {dot over (ω)}d2 and comprehensive slip rate Sd2 of wheel. According to separate or parallel operation state of two types of braking anti-collision and active brake of tire burst vehicle, a brake operation compatibility mode is used, to solve control conflict of two kinds of brake parallel operation. First, when the tire burst active braking or collision avoidance braking is carried separately, the operation of brake control of the two types does not conflict, and the control of tire burst active brake or anti-collision active brake can be carried independently. Second, in case of parallel operation of two types of braking, the braking compatibility control is determined by the following braking compatibility modes, according to the anti-collision coordination control mode and model. The brake compatibility controller takes one of parameters of the above two braking types as modeling parameter, to define the deviation eqd(t), eSd(t) e{dot over (ω)}d(t) between the active braking parameters Qd1 {dot over (ω)}d1
Sd1 and the coordinated braking parameters Qd2
ωd2
Sd2 of anti-collision for tire burst:
e
qd(t)=Qd1−Qd2,eSd(t)=Sd1−Sd2eωd(t)=ωd1−{dot over (ω)}d2
The “larger” and “smaller” values of control parameters of two braking types are determined by the positive and negative deviation (+, −). The “larger” value is determined when the deviation is positive, and the “smaller” value is determined when the deviation is negative. The braking control parameters of two types of active brake of tire burst and anti-collision coordination control for vehicle are processed according to anti-collision control mode of the front vehicle and rear vehicle. When the braking control are in the time zone tai of collision safety, the brake compatibility controller takes braking type of the “larger” value as the braking compatibility control type. One of Qd1, {dot over (ω)}d1, Sd1, {dot over (u)}x1 is acted as output of the braking compatibility controller. When the control of one of two brake types is in the collision risk or forbidden time zone tai, the brake compatibility controller takes braking type of the “smaller” value as the braking compatibility control type. One of the Qd2 Sd2
ux2 is acted as output of brake compatibility controller. In parallel operation of the two types brake, the control conflict between the two brake types is solved to realize the compatibility control of active brake of tire burst and anti-collision brake of driverless vehicle.
3). Drive-by-Wire Brake Control and Controller
The controller includes brake controllers of electric hydraulic and wire controlling machinery. The electric hydraulic brake controller is above-mentioned. The wire controlling machinery controller is based on electric hydraulic brake controller and adds mechanical brake controller by wire controlling. An equivalent conversion model of parameters is established by brake controller. The parameters for stroke Sw of brake pedal or/and pedal force Pw of brake pedal, which is detected by sensor, are converted into other parameter forms which include deceleration {dot over (u)}x of vehicle or/and total braking force of wheel, comprehensive angle deceleration {dot over (ω)}d and slip rate Sd, according to the transforming model. In the light of above model and algorithm of tire burst brake control, target control value of one of parameters Qd Δωd Sd for each wheel is determined. A dynamic control of brake control of brake-by-wire for tire burst is realized by logic cycle of control period Hh of brake A, B, C, D control and its combination. As parameters which include Qd, {dot over (u)}x, {dot over (ω)}d and Sd lagging respond to {dot over (S)}w or Pw, a compensator can be used, to carry out leading compensation for control phase of parameters. In the logic cycle of period Hh of brake control, the phase of low-frequency parameter signals Sw
{dot over (S)}w detected by sensor is consistent with phase of parameter signals Qd
{dot over (u)}x
{dot over (ω)}d
Sd by phase advance compensation, to improve the response speed of the brake control system and relevant parameters.
4). Environment Identification and Anti-Collision Control (Referred to as Anti-Collision Control) and Controller.
(1). Coordinated control of tire burst and collision avoidance. Radar, lidar and ultrasonic ranging sensors are used. A certain algorithm is used to determine relative distance Lt through the doppler frequency difference between transmitting and receiving waves. Define the relative speed of the front and rear vehicles: in the actual traffic detection, the sampling control period Ht is set. In period Ht is very small, the relative speed uc of the front and rear vehicles is determined by Δt and ΔLt, where ua is absolute speed of the front vehicle:
First. Self-adaption anti-collision control of vehicle. Based on environmental identification of the vehicle and rear vehicle, the anti-collision time zone tai is determined by relative distance Lti and relative speed uc between the vehicle and the rear vehicle. The tai is ratio of Lti and uc. A anti-collision threshold model with the parameter tai of front vehicle and rear vehicle is established by anti-collision coordination controller for tire burst. Setting decreasing threshold set cti of the tai, threshold values in set cti area set values which include Ct1 Ct2
Ct3
. . . Ctn. Based on threshold model, the anti-collision time zone tai of the vehicle and front vehicle or/and rear vehicle is divided into safety, danger, forbidden, collision levels which include ta1
ta2
ta3
. . . tan. Setting judgement conditions for collision between the vehicle and the rear vehicle: tan=ctn. A coordinated control mode of collision avoidance, steady braking of wheel and vehicle is established. According to the single wheel model of braking D control of vehicle, the target control value of vehicle deceleration {dot over (u)}x is determined. In limited range of target control series values of vehicle, acceleration and deceleration {dot over (u)}x of vehicle, the brake A, B, C control logic combination and its distribution to wheels are determined by parameter forms of angle deceleration {dot over (ω)}i or slip ratio Si of each wheel. In the cycle of period Hh, the steady state braking C control of vehicle is used preferentially by changing of the A, B, C brake control logic combination which included C⊂B∪A
A⊂C
C⊂A, under conditions of transformation of logic combinations between differential braking and its distribution to each wheel. The angle deceleration {dot over (ω)}i or slip rate Si for braking B control orderly is decreased with decreasing of tai or cti step by step, to keep differential braking force of vehicle steady state braking C control of balanced wheelset for tire burst and no-tire burst. When vehicle enters time zone of collision, all braking forces of each wheel are released, or drive control of vehicle is started, and the time zone tai of collision avoidance between the vehicle and the rear vehicle is limited in a reasonable range between “safety and danger”, to ensure that the vehicle does not touch the collision limit, namely, tai=ctn. The coordinated control of collision avoidance, wheel and vehicle steady-state braking are realized. Second, mutual adaptation anti-collision control for vehicle. The control is used for vehicles which be not equipped with distance detection system or only equipped with ultrasonic distance detection sensor. The controller of tire burst vehicle adopts a mutual adaptation control mode of steady-state braking and braking anti-colliding to rear vehicle. Based on experiment of driver's braking anti-collision, the driver's physiological response state to vehicle collision is determined. Based on the response state, a preview model of driver's braking anti-collision to tire burst front vehicle is established, and a braking coordination control model of the driver's physiological reaction lag time, braking control response time, brake retention time are established after the driver who is in rear vehicle finds tire burst signal of ahead vehicle. The above two models are collectively referred as the tire burst braking control model of collision avoidance of front and rear vehicles. In the early stage and real tire burst stage, the brake controller set by the tire burst vehicle carry on brake control, according to above two braking control model of collision avoiding of rear vehicle to tire burst front vehicle, to realize moderate braking of the tire burst vehicle. Based on the above two models, and brake A, B, C, D control logic combination and control cycle of period Hh, the coordinate and moderate braking control used by the front vehicle for tire burst can compensate time delay caused by the lag of physiological reaction and the reaction period of rear vehicle driver to collision avoiding, so as to avoid risk period of rear vehicle collide to front vehicle.
(2). Anti-collision control and controller for tire burst of vehicle driven by man. The vehicle anti-collision control in left and right direction adopts coordinated control mode, model and algorithm of braking, driving, rotation force of directive wheel or/and active steering. Based on rotation angle θea of directive wheel determined by active steering system AFS of vehicle, an actuator of AFS is exerted by additional angle θeb which is independent to driver operation. In the critical speed range of steady-state control of vehicle, an additional yaw moment which does not depend on driver's operation is determined to compensate the vehicle's insufficient or excessive steering caused by the tire burst. The actual steering angle θe of directive wheel is vector sum of the steering angle θea of directive wheel and the additional angle θeb of tire burst. In the active action of additional rotation angle θeb to tire burst, the vector sum of tire burst rotation angle tied and additional rotation angle θeb is zero. Running off of tire burst vehicle and excessive sideslip of directive wheel can be prevented by control of vehicle direction, wheel stability, vehicle attitude, stable acceleration and deceleration and path tracking of vehicle, to realize anti-collision control of the tire burst vehicle in left and right direction.
(3). Anti-collision control and controller t of driverless vehicle for tire burst
Based on coordinated control mode of anti-collision, braking, driving and stability of tire burst vehicle, the controller is equipped with control modules of machine vision, ranging, communication, navigation and positioning, to determine position of the vehicle, coordinates position from the vehicle to the front, rear, left, right vehicles and obstacles in real time; on this basis, the distance and relative speed between the vehicle and the front, rear, left, right vehicles and obstacles are calculated by control time zone of multiple levels which include safety, danger, no entry and collision. The collision-avoidance, steady-state of wheel and vehicle, and deceleration control of the tire burst vehicle are realized by independence or/and combination control of brake A, B, C, D in logic cycle of period Hh, control mode conversion of braking and driving, coordination control of active steering and active braking. The collision-avoidance control of tire burst vehicle includes collision-avoidance control of the vehicle and front, rear, left right vehicles, and around obstacles. According to the route planned by the controller, path tracking of the tire burst vehicle is carried, to arrive safe parking position of the vehicle.
5). Subroutine of Tire Burst Brake Control
According to the structure and process of tire burst brake control, brake control mode, model and algorithm of tire burst brake control subroutine or software is compiled. A structured programming is adopted. The subroutines mainly set control program modules that include control mode conversion, steady state of wheel, balance brake of vehicle, steady state of vehicle and total brake force (A, B, C, D) brake control, brake control parameters and A, B, C, D logic combination of brake control type, and include datum processing and control processing of brake, compatible control for tire burst active brake with pedal brake, brake and anti-collision coordination control of driven by man d and driverless vehicles, or/and set up brake program modules of drive-by-wire. The brake A. B, C, B control program modules include submodules of distribution and control of variables of brake A, B, C, D control type for wheels.
1). Rotation Force Control of Steering Wheel for Tire Burst
The tire burst steering control of vehicle adopts steering rotation moment control for tire burst, which includes control mode of rotation angle and rotation angle speed control of steering wheel, steering assist moment control of steering wheel and rotary torque control of steering wheel. When tire burst occurs, rotary torque for tire burst is generated, and direction of rotary torque of steering wheel exerted by ground changes sharply. Under action of tire burst rotary force, the steering assistant controller will misjudge direction of the steering assistant moment, and the steering assistant device outputs the steering assistant moment according to direction of steering assistant moment for normal working condition; the assistant moment aggravates unstable state of the vehicle steering, to result in double instability of tire burst and tire burst control in steering process of vehicle. Under common action of tire burst rotary force torque and steering assist moment, the steering wheel and directive wheel are drawn to deflection instantaneously by the two force torque, and the vehicle deviates from the right running direction sharply. Based on the types of rotation angle sensor and torque sensor used in the system, a direction judgement modes of steering angle and steering torque of vehicle are used to determine the direction of rotary force of tire burst, the direction of rotation moment of steering wheel exerted by ground, the direction of steering assistant force or steering resistance torque. On the basis of coordinates, rules, procedures and logic of tire burst direction judgement established by the steering system and based on control mode, model and algorithm of tire burst rotary force adopted by the steering assist controller, the steering assist device can provide corresponding steering assist or resistance moment for steering system at any angle of steering wheel, to realize steering rotary force control of tire burst vehicle.
(1). Control and Controller of rotation angle of steering wheel for tire burst
In steering control of vehicle for tire burst, a control mode and model of steering angle δ and rotation angle velocity {dot over (δ)} are adopted to limit the rotation angle of steering wheel and rotation angle velocity of vehicle, to balance and reduce the impact of tire burst rotation force to steering wheel and vehicle. The steering angle control of steering wheel adopts steering characteristic function Yki. The function Yki includes the function Ykbi which can determine limited value of rotation angle and angle velocity of steering wheel, and the function Ykai which can determine limited value of rotation angle of steering wheel.
i. i. Steering characteristic function Ykbi. A mathematical model of the steering characteristic function Ykbi is established by modeling parameters which include vehicle speed uix, ground comprehensive friction coefficient μk, vehicle weight Nz, steering angle δbi of steering wheel and its derivative {dot over (δ)}bi.
Y
kbi
=f(δbi,{dot over (δ)}bi,uxi,μk) or Ykbi=f(δbi,{dot over (δ)}bi,uxi,μk,Nz,)
Among them, the μk is a standard value set or a real-time evaluation value, the μk is determined by the average or weighted average algorithm of friction coefficient of directive wheels. The value determined by Ykbi is target control value or ideal value of rotation angle velocity of steering wheel. The value of Ykbi is determined by the above mathematical model or/and field test. The model structure of Ykbi is as follows: Ykbi is incremental function with increasing of friction coefficient μk, and Ykbi is incremental function of decreasing of speed uxi, and Ykbi is incremental function with increasing of angle δbi. Based on series value uxi[uxn . . . ux3 ux2ux4] of decreasing of vehicle speed uix, the target control values of set Ykbi [Ykbn . . . Ykb3
Ykb2
Ykb1] are determined by mathematical model with parameters rotation angle δbi of steering wheel and rotation angle velocity δbi at certain speed uxi. The values in the set Ykbi are limit values or optimal values which can be reached by δbi and δbi of steering wheel under condition of which speed uxi, ground friction coefficient μk and vehicle weight Nz are certain values. The eybi(t) between series absolute value of the target control value Ykbi of rotation angle velocity (>ybi for steering wheel and the series actual value of steering wheel rotation angle velocity {dot over (δ)}ybi′ of vehicle is defined under certain states of parameters uxi, μk, Nz and δbi. Under condition of certain vehicle speed uix, and when eybi(t) is positive (+), it is indicated that rotation angle velocity {dot over (δ)}ybi of steering wheel is in normal or normal working state. Under condition of which the vehicle speed uix is certain value, and when the deviation eybi(t) is less than 0, the rotation angle speeded {dot over (δ)}ybi of steering wheel is determined as tire burst control status. A mathematical model of steering assistant moment Ma2 of steering wheel is established by modeling parameter of deviation eybi(t) of controller:
M
a2
=f(eybi(t))
In the logical cycle of control period Hn of rotation moment for steering wheel, the value of steering assistant moment Ma2 of steering system is determined by mathematical model. Based on the positive (+) and negative (−) of deviation eybi(t), the steering assist moment or resistance moment to steering wheel is provided by steering assistant device, according to the direction of which absolutes value of rotation angle velocity for steering wheel is decreased. The rotation angle velocity of steering wheel is adjusted to make the deviation eybi(t) to 0. The rotation angle velocity deviation eybi(t) of steering wheel keeps tracking to its target control value, to limit the impact of tire burst rotary force to steering wheel.
ii. Steering characteristic function Ykai. A mathematical model of steering characteristic function Ykai is established by modeling parameters including vehicle speed uix, ground comprehensive friction coefficient μk, vehicle weight Nz, steering wheel angle δai and its derivative {dot over (δ)}ai.
Y
kai
=f(δai,uxi,μk)Ykai=f(δai,uxi,μk,Nz)
Among them, the value of μk is set as standard value or real-time evaluation value. The value of μk is determined by average or weighted average algorithm of friction coefficient of steering wheels. The value of Ykai is target control value or ideal value of steering wheel angle. The value of Ykai is determined by the above mathematical model or/and field test. The modeling structure of Ykai is as follows: the Ykai is an incremental function of increasing of μk, the Ykai is an incremental function of decreasing of uix, and the Ykai is an incremental function of increasing of steering angle δai steering wheel. According to series value uxi[uxn . . . ux3 ux2
ux1] of decreasing of vehicle speed uxi, the set Ykai[Ykan . . . Yka3
Yka2
Yka1] of target control values of corresponding steering angle δai of steering wheel are determined by mathematical model at each speed. The values in the Ykai set are a limit value or a optimal values of the steering angle of steering wheel at a certain speed uix, ground comprehensive friction coefficient μk and vehicle weight Nz. The deviation eyai(t) between the target control value Ykai of rotation angle of steering wheel and the actual value of rotation angle δyai of steering wheel is defined under certain states of parameters uix, μk and Nz. When deviation eyai(t) is positive (+), it is indicated that rotation angle δyai of steering wheel at this time is within limit value of δyai, and is indicated rotation angle of steering wheel δyai is within the normal range. When deviation eyai(t) is negative (−), it is indicated that rotation angle δyai of steering wheel is beyond limited range which is determined by rotation angle control of steering wheel for tire burst. A mathematical model of steering assistant or resistance moment Ma1 is established by modeling parameter of deviation eyai(t). In logical cycle of control period Hn of rotary moment for steering wheel, the direction of which decrease of absolutes value of rotation angle δ for steering wheel is determined according to positive (+) and negative (−) of deviation eyai(t), and steering assistant or resistance moment Ma1 is determined by mathematical model. Based on steering assistant or resistance moment Ma1, a rotation moment to steering system is provided by steering assist motor, to limit the increase of steering wheel angle δ. The target control value Ykai of rotation steering of steering wheel is tracked by its actual angle δ, until eyai(t) is 0. The rotation angle δ of steering wheel under the condition of tire burst is limited in region of ideal or maximum value of steering slip angle of vehicle. The control may be not complete direction judgment of related parameters for tire burst.
(2). Control and controller of power-assisted steering for tire burst
i. Assistance steering control of tire burst. The direction judgement of tire burst for the control uses two mode of torque angle or torque. On the basis of direction determination mode for tire burst, it is determined that direction of steering angle δ and torque Mc of steering wheel, or steering angle δ and torque Mc of directive wheel, and rotation moment Mk of directive wheel exerted by ground, rotation moment for tire burst and steering assistance moment Ma. Among them, Mk includes the rectifying torque Mj of wheel and tire burst rotation moment Mb′ of directive wheel exerted by ground and resistance moment of directive wheel. A control model of power assistance steering and characteristic function of tire burst are determined by control variable including rotation torque Mc of steering wheel and parameter variable including vehicle speed ux. First. On positive and negative stroke of rotation angle δ of steering wheel, a control model of steering assistance moment is established by variable Mc and parameter ux under normal working condition:
M
a1
=f(Mc,ux)
The characteristic function and characteristic curve of steering assist moment Ma1 are determined by the model under normal working condition. The characteristic curve includes three types of straight line, broken line or curve. The modeling structure and characteristics of steering assistant moment Ma1 are as follows. On positive and reverse stroke of rotation angle of steering wheel, the characteristic functions and curves are same or different. The so-called “difference” refers to: on the positive and negative stroke of rotation angle of steering wheel, the characteristic function adopted by control model of the Ma1 is different, and value of the Ma1 is different in same value or point of variable and parameter, otherwise it is same. The steering assistant moment Ma1 is decreasing function with increment of vehicle speed ux; the Ma1 is incremental function of absolute value of increment of rotation torque Mc of steering wheel. Based on calculated values of each parameters, a numerical chart which is stored in the electronic control unit is drawn. Under normal and tire burst conditions, the electronic control unit by means of looking-up table call power assistance steering control procedure and extracts the target control value of steering assistant moment Ma1 of steering wheel, based on parameters of rotation torque Mc of steering wheel, vehicle speed ux and rotation angle δ of steering wheel. After the direction of tire burst rotation force Mb′ is determined, a mechanical equation of steering assist control for tire burst are adopted to determine the target control value of tire burst rotation force Mb′. In steering assistant control for tire burst, the rotating moment Mb′ of tire burst is balanced by an additional assistant moment Ma2, namely, the Ma2 equals the Mb:
M
a2
=−M
b
′=M
b
Under the condition of tire burst, the target control value of steering assistant moment Ma is vector sum of detection value Ma1 of torque sensor of steering wheel and additional balanced steering assistant moment Ma2 for tire burst. In rotary moment control of steering wheel, the phase advance compensation of steering assistant moment Ma is carried out by compensation model to improve response speed of power steering system EPS. When necessary, the steering assist control and rotation angle control of steering wheel for the tire burst are constituted as a composite control. The stable steering control of tire burst vehicle can be realized effectively by limiting maximum angle or/and rotation angle velocity of steering wheel. According to the relationship model between steering assistant torque Ma and electrical control parameters of electrical power steering system, the steering assist torque Ma is converted into control parameters of power device, in which it includes current ima or/and voltage Vma. The steering assist control sets limiting value ab of balance rotary moment |Mb| for tire burst. In control, |Mb| is less than ab which is larger than the maximum value of the rotary moment of tire burst |Mb′|. The maximum value of |Mb′| is determined by field tests. A phase compensation model of assistance steering is established by tire burst steering assistance controller. The advance compensation of phase of the steering assistance moment Ma is carried out by the compensation model in the control, to improve the response speed of rotary force control of steering wheel.
(3). Control and controller of rotary torque of steering wheel for tire burst
i. Determining of tire burst direction. The determination of tire burst direction uses one of modes of angle and torque, angle, to realize judgement of direction of steering assistant moment Ma and operation direction of electric device directly. Defining deviation ΔMc between target control value of steering torque Mc1 of steering wheel and the real-time value Mc2 detected by torque sensor of steering wheel:
ΔMc=Mc1−Mc2
The parameters direction of steering assistant moment Ma and the direction of steering power parameters of electric device are determined by the positive and negative (+, −) of deviation ΔMc. The direction of steering power parameters include the direction of the current im of the motor or the rotating direction of the assistant motor. When increment ΔMc of rotation torque Mc of steering wheel is positive, the direction of steering assistant moment Ma is the direction of increasing of assistant moment Mc; when ΔMc is negative (−), the direction of steering assist moment Ma is the direction of decreasing of steering assistant moment Ma, that is, the direction of increasing of resistance moment Ma.
ii. Rotation torque control of steering wheel. A control mode, control model of rotation torque Mc of steering wheel and characteristic function are established by control variable rotation angle δ of steering wheel, parameter speed ux and rotation angle velocity {dot over (δ)} of steering wheel under normal working conditions:
M
c
=f(δ,ux)Mc=f(δ,{dot over (δ)},ux)
The model determines characteristic function and characteristic curve of rotation torque of steering wheel under normal working conditions. The characteristic curve includes three types: straight line, broken line or curve. The value determined by the control model of rotation torque Mc of steering wheel and characteristic function are target control value of steering wheel rotation torque of vehicle. The model structure and characteristics of the Mc are as follows. On the positive or negative stroke of rotation angle of steering wheel, the characteristic function and curve are same or different, the so-called “difference” means: in the positive and reverse stroke of rotation angle of steering wheel, the characteristic function for Mc is different, and the value of Mc is different at same point of variable and parameter, otherwise it is same. The steering wheel rotation torque Mc determined by control model of steering assistant moment is decreasing function of increment of the parameter ux, and is incremental function of the absolute value of increment of δ and {dot over (δ)}. Based on calculated values of each parameter, a numerical chart which is stored in the electronic control unit is drawn. Under normal and tire burst conditions, through look-up table method, control procedure of power assistant steering is called by electronic control unit, and target control value of steering assistant moment Mc1 of steering wheel is extracted from the electronic unit, based on parameters of steering wheel angle δ, rotation angle velocity {dot over (δ)} of steering wheel and vehicle speed ux. The actual value of rotation torque Mc2 of steering wheel is determined by the real-time detection value of torque sensor. Defining the deviation ΔMc of rotation torque Mc of steering wheel between the target control value of steering wheel torque Mc1 and the real-time detection value Mc2 of torque sensor of steering wheel:
ΔMc=Mc1−Mc2
The steering assistance or resistance moment Ma of steering wheel is determined by the function model of deviation ΔMc under normal and tire burst conditions.
M
a
=f(ΔMc)
Based on the steering characteristic function, the rotation torque control of steering wheel uses variety of modes. Mode 1. Basic rectifying torque type. Base on the mode, a function model of rotation torque Mc for steering wheel are set up by modeling parameters of vehicle speed ux and steering wheel angle: Mc=f(δ, ux), The target control value of Mc1 is determined by specific function forms which include broken line and curve. At any point of rotation angle of steering wheel, the derivative of Mc1 basically is the same as the derivative of aligning torque Mj. Under action of the Mj, driver of vehicle can obtain the best or better road sense from steering wheel. In function model of rotation torque Mc1 of steering wheel, the Mc1 and the Mj are incremental function of the increase of steering wheel angle δ at certain speed ux, and Mc1 is irrelevant to the steering wheel angle velocity {dot over (δ)}. The real-time detection value Mc2 of torque sensor of steering wheel or/and road sense which is transmitted by steering wheel changes with the changing of the steering wheel angle velocity {dot over (δ)}. Mode 2: Balanced aligning torque model, function model of rotation torque Mc of steering wheel is established by modeling parameters of vehicle speed ux, rotation angle δ of steering wheel and rotating angle velocity {dot over (δ)}: Mc=f(δ, {dot over (δ)}, ux). In the model of Mc, target control value Mc1 of Mc is determined by concrete function form of the model. At any point of rotation angle of steering wheel, the derivative of Mc1 basically is same as that of aligning torque Mj. The derivative of Mc1 basically is same as the derivative of the aligning torque Mj of directive wheel. In torque function model of the Mc, the Mc1 increases with the increase of δ under condition of a certain speed ux. Meanwhile, the target control value Mc1 of torque Mc of steering wheel and the real-time detection value Mc2 determined by steering wheel torque sensor are correlated synchronously with angle velocity {dot over (δ)} of steering wheel. In each logic cycle of steering torque control period Hn of steering wheel, the Mc1 and Mc2 increase or decrease synchronously with the increasing or decreasing of δ on appropriate proportions in the positive and reverse stroke of steering wheel angle δ. Based on the definition of rotation torque of steering wheel, the ΔMc of rotation torque Mc of steering wheel is a difference value between Mc1 and Mc2:
ΔMc=Mc1−Mc2
A functional model of steering assistant moment Ma is established, the value of Ma is determined by model of difference ΔMc.
ΔMc=f(ΔMc)
Under the action of steering assist or resistance torque Ma, the driver can obtain the best feel or road feel from steering wheel of steering system, no matter what steering system is in normal or tire burst working condition. Adjustment force of steering assistance for steering wheel torque is enlarged. According to relationship model between rotation torque of steering wheel and power parameters, the ΔMc is converted into power parameters of electric devices, in which the parameters Mc, current icm and voltage Vmc are vectors.
(4). Control subroutine or software of tire burst rotation moment
Based on control structure, control flow, control mode, model and algorithm of tire burst rotation force (moment), a subprogram of tire burst rotation moment control is developed. Subprogram use a structured design. The subprogram mainly sets direction determination modules of related parameters including rotation angle and rotation torque of steering wheel, and rotation moment of power assistance steering. Steering subroutine of steering wheel mainly is composed by program modules of rotation angle δ and rotation angle speed of steering wheel. Control program module of steering assistant torque for tire burst mainly is composed by E control program module of steering assistant torque under normal working conditions and G control module of relationship between steering assistant torque and current or/and voltage of steering assistant device, and program module of control algorithm for tire burst rotation torque.
2).
Tire burst active steering control for driven by man vehicle or the active steering control of an vehicle driven by man with an auxiliary steering interface for a tire burst. The tire burst active steering control covers vehicles which are driven by chemical energy and electric drive. In the process of tire burst, the active steering control of tire burst vehicle includes additional steering angle of active steering and electronic servo power steering control, as well as coordinated control for additional angle of active steering and rotation driving moment of directive wheel. When the burst control entering signal ia arrives, the active steering control starts. Based on active steering system (AFS), vehicle stability control program (ESP) or/and four wheel steering (FWS) system, the active steering system for tire burst use mainly coordinated control mode of AFS and ESP. The coordinated control mode of AFS and ESP is realized by active steering controller of electronic mechanical or controller of steering of drive-by-wire with road sense controller. The controller uses active steering control structure, and set control process, control mode, model, algorithm and control program or software. When tire burst signal I arrives, the control and control mode converter takes tire burst signal I as the conversion signal, and adopts three kinds of mode and structure of program conversion, protocol conversion and conversion of external location, to realize entering and exiting of tire burst control, and control and control mode conversion for normal and tire burst working conditions.
(1). Active steering control and controller of driven by man vehicle and the active steering driverless vehicle with an auxiliary steering interface for tire burst
i. Active additional angle control and controller for tire burst. According to coordinate system and judging rules, procedures and judging logic of tire burst direction determined by the method, the insufficient and excessive steering of vehicle are determined by positive and negative (+, −) of direction of steering wheel rotation angle δ and yaw angle velocity deviation eωr(t) of vehicle. On the basis of direction judging of steering wheel angle δ, insufficient or excessive steering of vehicles and position of tire burst wheel, the direction of additional rotation angle θeb (+, −) of directive wheel, which is used by tire burst steering control of vehicle, is determined. On the basis of its direction judging, a balancing tire burst additional angle θeb which is independent of the driver's operation is applies to actuator of active steering system (AFS), to compensate for the insufficiency or excessive steering of vehicle. The actual angle θe of directive wheel of vehicle is vector sum of both for steering angle θea of directive wheel determined by driver's operation and the balancing tire burst additional rotation θeb
θe=θea+θeb
The direction of balancing tire burst additional angle θeb is opposite to the direction of steering angle θeb′ of tire burst of wheel.
θeb=−θeb′
In linear superposition of angle θeb and angle θeb′, the vector sum of angle θeb and angle θeb′ is 0. A control mode and model of the additional balance angle θeb of directive wheel to tire burst are established by the modeling parameters which include vehicle yaw angle velocity ωr, vehicle sideslip angle β to vehicle quality center, or/and lateral acceleration {dot over (u)}y, adhesion coefficient φi or friction coefficient μi and slip Si of directive wheel. Based on tire burst state parameter and stage determined by the state parameters, the target control value of additional steering angle θeb of directive wheel tire burst is determined by using corresponding control mode or/and algorithm which includes PID, sliding mode control, optimal control or fuzzy control for modern control theory:
θeb(eωr(t),eβ(t),e(Se),{dot over (u)}y)
The equivalent function model includes:
θeb=f(eβ(t),eωr(t),θeb=f(eωr(t),eβ(t),{dot over (u)}y),θeb=f(eωr(t),eβ(t),e(Se))
Based on mechanical analysis of tire burst steering angle θeb′, the θeb′ can be divided as θeb1′, θeb2′, θeb3′:
In formula, Ri0, Ri, b, e(ωe), e({dot over (ω)}e), e(Se), Mb′, uy, ux and eωr(t) are respectively standard radius of wheel, radius of tire burst wheel, distance between two wheels of front axle or rear axle, equivalent relative angle speed deviation, angle deceleration speed deviation, slip rate deviation of tire burst balance wheelset for steering or non-steering, tire burst rotation force (torque) of steering wheel, vehicle lateral acceleration or deceleration, vehicle speed, deviation between ideal yaw angle rate ωr1 and actual yaw angle rate ωr2 of vehicle. Defining the deviation eθ(t) between target control value θe1 of directive wheel angle θe and its actual value θe2, a control model of directive wheel angle θe is established by modeling parameter of deviation eθ(t). The control adopted open-loop or closed-loop control. In the control cycle of period Hy, the active steering system AFS adopt a actuator that can superimposes two vector of directive wheel angle θea and additional balanced angle θeb for tire burst. The actual value of rotation angle θe2 of directive wheel is always tracked to its target control value θe1, to realize the control which deviation eθ(t) is 0. In the active steering control of tire burst, when necessary, a coordinated control mode of rotation angle θe of directive wheel of vehicle and differential braking of electronic stability control program ESP can be adopted by active steering controller for tire burst
ii. Steering control and controller of electronic servo power for tire burst
The servo power steering control of active steering for tire burst includes direction judgement for tire burst and servo power control for tire burst. When tire burst occurs, rotary force produced by tire burst and servo-assisted control in normal working conditions will lead to double instability of tire burst and its control of vehicle. Therefore, servo-assisted steering controller for tire burst vehicle should be established. First. The direction determination of tire burst. The coordinates, rules, procedures and logic of determination of tire burst direction are established by this method. The direction judgement of rotation moment of directive wheel exerted by ground, the steering assist or resistance moment of the directive wheel are determined by angle and torque mode of direction judgement. The determination of direction of tire burst become to the basis of tire burst assist steering control and the tire burst active steering control. Second. Tire burst power steering control. Torque control mode and model of tire burst assist steering or tire burst active steering of vehicle are determined by this method. Control mode 1, tire burst assist steering. A control model of the steering assist moment Ma and characteristic function of Ma are established by control variable Mc, parameter variable speed ux and steering wheel angle δ, to determine steering assist moment Ma1, additional balancing moment Ma2 for tire burst and their sum of vectors. Among them, the tire burst rotation moment Mb′ can be balanced by additional balancing moment Ma2. The target control value of steering assisting or resistance moment Ma of vehicle is determined, and the phase leading compensation of steering assist moment Ma is carried out by the compensation model. Control mode and model 2, assist steering for tire burst. Torque control mode of tire burst of steering wheel. A torque control model of steering wheel and characteristic function are established by modeling parameters rotation angle δ of steering wheel, vehicle speed ux and rotation angle velocity {dot over (δ)} of steering wheel, to determine target control value of torque steering Mc1 of steering wheel and the deviation ΔMc between the target control value of steering wheel torque Mc1 and real-time value torque Mc2 of steering wheel measured by torque sensor. Based on the function model with deviation ΔMc, the steering assist or resistance moment Ma of steering wheel is determined under normal and tire burst conditions. In the logic cycle of steering control period Hy of vehicle, the servo power assisting or resistance moment can be adjusted actively by electronic servo power steering controller at any steering position of steering wheel, therefrom to realize the power steering control for vehicle tire burst in real-time.
iii. Active steering control subroutine or software to tire burst of vehicle driven by man
Based on the control structure and process, control mode, model and algorithm of tire burst active steering, a control subroutine of tire burst active steering is developed. The subroutine is designed by using a structured pattern. The subroutine is composed by modules which include control module of steering wheel rotation angle of active steering, module of additional steering angle of steering wheel or directive wheel to tire burst. Direction judgment module of electronic servo power assisted steering, assistance torque control modules of electronic servo steering or/and coordination control program modules of tire burst active steering and electronic stability control program system (ESP) are used.
(2). Active steering control and controller with driven by man vehicle with drive-by-wire
Steering control of drive-by-wire is a kind control by high-speed fault-tolerant bus connection, high-performance CPU control and management. The control is realized by operation to steering wheel. Redundancy design is adopted by steering control. A combination system of steering of drive-by-wire to wheel is set up. The combination system includes drive-by-wire steering of front-wheel and mechanical steering of rear-wheel, or drive-by-wire steering of front and rear axle, or drive-by-wire steering of four-wheel of electric power vehicle. Drive-by-wire steering control of vehicle includes steering control of directive wheel and steering road sense control of steering wheel. The steering control of directive wheel adopts the coupling control mode of two parameter of rotary angle θe and rotary driving moment Mh of directive wheel. The absolute coordinate system set in vehicle is established. The coordinate system of steering control stipulates that zero point of directive wheel rotation angle θe is origin. Whether the vehicle or wheel turns to left or turns right, the positive route of rotation angle of directive wheel, that is the increment or direction of the rotation angle is defined as positive (+), and the negative route of rotation angle of directive wheel, that is decrement of rotation angle θe, or direction of rotation angle θe is defined as negative (−). A relative coordinate system is set in the steering axle of steering system. Relative coordinate system rotates with steering axle of steering system. The origin of coordinate system is zero point of the steering torque and steering angle. The absolute and relative coordinates of above-mentioned steering angle and steering torque are used for the control of the steering angle and steering torque of the drive-by-wire active steering system. Based on dynamic equation of steering system, a dynamic model for tire burst is establishes by the parameters that includes rotation angle θe of directive wheel, rotation moment Mk of directive wheel exerted by ground and rotation driving moment Mh transmitted by motor to steering wheel:
M
h
−M
k
=j
u{umlaut over (θ)}e−Bu{dot over (θ)}eMk=Mj+Mb′+Mm
In the formula, ju and Bu are equivalent rotational of inertia and equivalent resistance coefficient of steering system, Mb′ is the rotating moment of tire burst, Mm is rotating friction torque of directive wheel exerted by the ground, the Mj is the aligning torque. The magnitude and direction of Mk change dynamically. Based on structure of steering system, a dynamic model of steering system which includes motor, steering mechanism (gear, rack) and wheel is established. The model is transformed by Laplace transform to determine transfer function. The corresponding control is realized by steering controller on algorithm which includes PID, fuzzy, neural network and optimal of modern control theory. The steering controller is designed, to make response time and overshoot of the system keep in an optimal range. In steering control, a dynamic response of relevant parameters including vehicle yaw rate ωr is determined by control for ideal transmission ratio and dynamic transmission ratio Cn of steering system, state feedback of parameters such as yaw rate ωr and centroid side deflection angle β of vehicle, the control coupling of angle θe of directive wheel and rotation moment Mk of steering wheel exerted by ground, steering driving moment Mh of steering system, thereby to solve some technical problems about overshoot and stability steering of vehicle, sharp change of magnitude and direction of rotating moment Mb′ etc. First, dynamic models of the steering system which includes steering motor, gear transmission device and directive wheel can be established:
In the formula, Tm Jm
θm
Bm
G
kt
im are respectively rotation torque of motor, turn round inertia, rotation angle, viscous friction coefficient, rotation speed ratio, electromagnetic torque constant of motor and current of motor. The Ta is moment of pinion shaft. The Ta is determined by the mathematical model of rotation moment Mk of directive wheel:
T
a
=f(Mk)
The Mk is determined by test parameter value of the torque sensor set in the steering system. When equivalent model is adopted:
T
a=λaMk
λa is equivalent coefficient. The λa is determined by parameter including moment of inertia Jma, viscous friction coefficient and other parameters of the wheel and steering mechanism.
Second, steering motor and electrical model
V
m
=Ri
m
+L
m
i
m
+k
i{dot over (θ)}m
Where, Vm R
Lm are counter electromotive force, armature resistance and inductance respectively
Third, model of steering wheel and steering mechanism:
T
a
−T
r
=J
s{umlaut over (θ)}s+Bs{dot over (θ)}s
In the formula, the Tr Js
Bs are equivalent steering resistance moment of pinion shaft, the moment of inertia of steering wheel and steering mechanism, viscous friction coefficient of each transmission device. Neglecting torsional rigidity of motor, the transfer function is obtained by the speed matching between the motor and the pinion shaft. Neglecting the Tr, The Laplace transformation is performed to obtain transfer function:
The dynamic model established by modeling parameters which include wheel rotation angle θe, steering rotation moment Mk and rotation driving moment Mh of directive wheel are transformed by Laplace transform, to determine transfer function. A steering controller is designed through corresponding control algorithm which include PID, fuzzy, neural network and optimal modern control of modern control theory. The control modes and models are used to normal and tire burst working condition, bumpy road surface, overshoot of driver and fault of vehicle. The coupled control mode of two-parameter for steering wheel rotation angle θe and rotation driving moment Mh of steering wheel are adopted. The steering controller is designed to make response time and overshoot of the system keep in an optimal range. In steering control, a dynamic response of relevant parameters which include vehicle yaw angle rate ωr is determined by control for ideal transmission ratio or dynamic transmission ratio Cn of steering system, state feedback of parameters such as yaw rate ωr and centroid side deflection angle β of vehicle, the control coupling of rotation angle θe of directive wheel and rotation moment Mk of steering wheel exerted by ground, steering driving moment Mh of steering system, thereby to solve some technical problems about overshoot and stability steering of vehicle in sharp change of magnitude and direction of rotating moment Mb′. The deviation eδ(t) between target control value δ1 of rotation angle δ of steering wheel and its actual value δ2 is defined. The deviation eθ(t) between target control value Qe1 of steering wheel angle θe and its actual value θe2 is defined. The deviations eδ(t) and eθ(t) are used to determine driving direction of rotary driving moment Mh of directive wheel and direction of control parameters θe and Mh.
i. Rotation angle θe control of directive wheel for tire burst. In the coordinate system determined by this method, the steering angle of vehicle and wheels, the yaw angle velocity of vehicle and insufficient or excessive steering angle of vehicles are vectors. Angle θea of directive wheel is determined by steering wheel angle θea under normal working conditions. Under tire burst working conditions, an additional burst tire balanced angle θeb which is independent of the driver's steering control and operation is applied to directive wheel of steering system by controller of rotation angle of steering wheel. Within critical speed range of vehicle steady-state control, the insufficiency or oversteering steering of tire burst vehicle is compensated by θeb. The target angle θe of directive wheel is a linear superposition value of vector of directive wheel angle θea and the additional balance angle θeb: θe=θea+θeb. The transmission ratio Cn between steering wheel angle θe and directive wheel angle θe is a constant value or dynamic value. The dynamic value is determined by mathematical model with parameter vehicle speed ux. The mathematical model determined of additional balance angle θeb for tire burst is established by modeling parameters including vehicle speed ux, rotation angle δ of steering wheel, yaw angle velocity eωr(t) of vehicle, sideslip angle eβ(t) to mass center of vehicle, or/and ground friction coefficient and lateral acceleration {dot over (u)}y. The target control value of θeb is determined. Setting control period Hy of vehicle steering, and the Hy is as a set value, or the Hy is a dynamic value determined by mathematical model of modeling parameters which includes angle increment Δδ of steering wheel and frequency fy in unit time. Among them, the Δδ is called the comprehensive increment of rotation angle of steering wheel. Or the Δδ is a ratio between absolute value sum of positive and negative changing value of directive wheel rotation angle and the number n of angle changing in unit time: Δδ=(|Δδ1|+|Δδ2| . . . +|δn|)/n. The frequency fy is determined by the response frequency of the motor or steering system. The coordinated control model of directive wheel angle θe and rotation driving moment Mh of directive wheel is established by modeling parameters which includes deviation eδ(t) between the target control value of steering wheel angle δ1 and its actual value δ2, or the deviation eθ(t) between the target control value of directive wheel angle θe1 and its actual value θe2. The driving direction and value of rotation driving moment Mh are determined. In control cycle of period Hy, the actual value of rotation angle θe2 of directive wheel always traces its target control value θe1 under the action of rotating driving moment Mh.
ii. Rotary driving torque control and controller of steering wheel for tire burst
According to the regulations of magnitude and direction of angle and torque in coordinate system of the drive-by-wire active steering, two sets of independent coupling and coordinating control systems of rotation angle δ and rotation driving torque Mh of steering wheel in left steering and right steering of vehicle are established on left side and right side of origin position of steering wheel angle δ. In the origin of steering wheel angle δ, namely zero point of left steering or right steering of vehicle, the direction conversion of electric control parameters of electric drive device are realized by electronic control unit of controller, therefrom, to adapt coupling or coordinated control of two control variables θe and Mh. The electric control parameters of direction conversion include current or voltage. Based on dynamic equation of steering system, a control model of driving moment Mh of directive wheel for driven by man vehicle is established by coordinated control variables θe and Mh, modeling parameters which include the rotation force Mk of directive wheel exerted by ground, deviation eδ(t) of target control value of steering wheel rotation angle δ and its actual angle value, or/and rotation angle velocity {dot over (δ)}e. On the basis of control model, target control value of Mh is determined. According to the positive and negative of deviation eδ(t) between the target control value δ1 and its actual value δ2 of steering wheel, direction of rotation driving moment Mh of directive wheel is determined. The rotation moment Mk of directive wheel exerted by ground includes the rotation moment Mb′ of tire burst. When tire burst of vehicle occurs, the size and direction of change. Rotation angle θe of directive wheel is controlled, and rotation driving moment Mh of directive wheel needs to be adjusted in real time. Two modes are used to determine the Mh. Mode 1: the rotation torque sensor set in the between directive wheel and the steering system of mechanical transmission device detects the rotation torque Mk of directive wheel exerted by ground. According to differential equation:
M
h
−M
k
=j
u{umlaut over (θ)}e−Bu{dot over (θ)}e
Target control value of Mh is determined. Where, ju Bu are equivalent moment inertia and equivalent resistance coefficient of steering system respectively. In view of lagging of detection signal of sensor, the phase compensation of Mk is carried out. In steering control cycle of period Hy, a compensation coefficient Ge(y) is determined by the mathematical model with modeling parameters which include the deviation e(θe) between target control value θe1 and actual value θe2 of rotation angle of directive wheel and its derivative e(θe), and damping coefficient Q of transmission device:
G
e(y)=f(e(θe),ė(θe),Hy)
Where Ge(y) is an increasing function to increment of absolute values of e(θe) ė(θe) and
. Mode 2. In the steering control cycle of period Hy, a equivalent mathematical model is established by modeling parameter including parameters e(θe) and e(ωe), to determine rotation moment Mk of directive wheel exerted by ground and rotation driving moment Mh of directive wheel. The mathematical model includes:
M
k
=f(θe1,θe2,ė(θe),e(ωe),e({dot over (ω)}e)),Mh=ju{umlaut over (θ)}e−Bu{dot over (θ)}e+Mk
The equivalent mathematical model for determining driving torque Mh of directive wheel of vehicle driven by man or driverless vehicle is adopted. The mathematical expression includes:
In the control model and formula, the Jn is equivalent moment inertia of directive wheel of drive system, the Ge(y) is leading compensation coefficient, The Hy is steering control period, the e(θe) is drivative of deviation between the target control value of directive wheel angle θe1 and its actual value of θe2, k1 and k2 are coefficients. The equivalent relative angle velocity deviation ė(θe) of the left wheel and right wheel of the balance wheelset can be replaced by the equivalent relative slip ratio deviation e(Se) of two directive wheels. The torque sensor is set on steering driving axle. Defining deviation em(t) of rotary driving moment between detected value Mh2 of the sensor and target control value Mh1 of rotary driving moment of directive wheel, open-loop or closed-loop control is adopted during logical cycle of steering control period Hy. The target control value Mh1 of rotary driving moment of directive wheel is always tracked by actual value of driving force Mh2 by feedback control of deviation em(t). The driving device for drive-by-wire steering includes motor and transmission device. Based on the interaction of rotation moment Mk of directive wheel exerted by ground and rotary driving moment Mh of directive wheel, the target control value θ1 of directive wheel angle θe is always tracked by its actual value θ2, by means of active or self-adaptive joint adjustment and coupling control of rotation driving torque Mh and steering wheel angle θe in any position of left turning or right turning of vehicle, and under the action of coordination control of driving torque Mh and rotation angle θe of directive wheel. For vehicle of left running or right running, and at zero position of steering angle of directive wheel, the controller will make one conversion to direction of electronically controlled parameters including rotation driving torque Mh of directive wheels. In left steering or right steering of vehicle, the direction of electronically controlled parameters that includes current and voltage are opposite, to realize the conversion of rotation direction of driving torque Mh. In the control process of left-turn and right-turn of vehicle, two sets coupling control systems which are independent and coordinate each other are established by direction conversion and control of parameters of rotation angle δ of steering wheel and driving rotation moment Mh of steering driving system in both sides of zero position of the δ and the Mh, according to coordinates rule set by vehicle. Whether vehicle is in state of straight running or steering, the tire burst rotation moment Mb′ is generated when tire burst of wheel occurs, therefrom to cause changes of the size and direction of the rotation moment Mk of directive wheel exerted by ground. At any position of angle θe of directive wheel and angle δ of steering wheel, the deflection and displacement of directive wheel angle θe and steering wheel angle δ for tire burst are generated immediately. In the first time of appearing of rotating moment deviation eθ(t) of directive wheels and deviation eδ(t) of rotation angle of steering wheel for tire burst, the direction of tire burst rotation moment Mb′ and rotation moment Mk of directive wheel exerted by ground are determined. At the same time, the control direction of directive wheel angle θe and the rotation driving moment Mh also are determined. When the tire burst rotation moment Mb′ is produced by tire burst, the rotation driving moment Mh2 of directive wheel is timely detected by torque sensor set between the driving shaft and the directive wheel. A mathematical model of rotation driving moment of directive wheel is established by the parameters that include rotation driving moment em(t) between the target control value Mh1 and its actual value Mh2 of directive wheel. According to the mathematical mode, the value of the rotary driving force Mh of directive wheel is adjusted in the cycle of period Hy of steering control, so that target control value of rotation angle θe of directive wheel is tracked by its actual value. The direction deviation of directive wheel and vehicle, which are caused by impact of tire burst rotating moment Mb′ is eliminated or is compensated, to realize stability control of tire-burst vehicle. Road-sense control and controller. Based on the relationship model among rotation angle of steering wheel, vehicle speed, lateral acceleration and steering resistance moment, a control mode of real road-sense is adopted. A mathematical model of road induction feedback force Mwa of a road induction device is established by control variables including driving moment Mh of directive wheel or/and ground rotation moment Mk of steering wheel exerted by ground, and by modeling parameters including relevant parameters of ground, vehicle and vehicle steering, to determine the target control value of road induction feedback force Mwa. The road sensor device which include road induction motor or road induction device of magnetorheological output feedback force of road sense. By motor of road induction or of road induction device of magnetic current variant, the driver can obtain road sense information which reflects road surface, wheel, running state and tire burst state of vehicle.
iii. Active control subroutine or software of drive-by-wire steering of vehicle driven by man.
Based on the structure, flow, control mode, model and algorithm of the active steering control, a control subroutine of the active steering control of vehicle is compiled. A subroutine of structured design is used. The subroutines include direction determination modules of rotation angle δ of steering wheel, tire burst rotation moment Mb′ or rotation moment Mk of directive wheel exerted by ground, rotation driving moment Mh of directive wheel; the subroutines include control program module of rotation angle θea of directive wheel, additional angle θeb of directive wheel, rotation moment Mk of directive wheel exerted by ground, driving rotation moment Mh of directive wheel, and coordination control program module of the active steering and electronic stability control program system ESP, or/and program module of real road sense for tire burst or no tire burst.
3). Active Steering Control and Controller of Driverless Vehicle
(1). Central controller of driverless vehicle. The central master controller includes sub-controllers of environment perception and recognition, positioning and navigation, path planning, control decision for normal and tire burst working state, it includes fields of tire burst vehicle stability control, tire burst collision prevention, path tracking, addressing to parking and path planning of parking. When the entering signal ia of tire burst control arrives, the vehicle get into a control mode for tire burst: the central controller sets up various sensors of environmental perception and vehicle control, and set up machine vision, global satellite positioning, mobile communication, navigation, artificial intelligence controllers, or/and sets up intelligent vehicle network controller in condition of which intelligent vehicle network has be established. During state process and control period of tire burst, steady state of wheels, stability and attitude control of vehicles, stable deceleration or acceleration control of the whole vehicle in a entirety are planned by environment perception, positioning, navigation, path planning and control decision-making of vehicle, according to direction of tire burst, tire burst control mode, model and algorithm of braking, driving, rotation force of steering wheel, active steering and suspension control; the central master controller unified plans coordination control of lane holding of tire-burst vehicle, anti-collision control of the vehicle to the front and rear vehicles or/and with obstacles; the central master controller makes a strategic decision of vehicle speed, running path and path tracking of vehicle, or/and makes a decision of parking location and path to the parking site after vehicle tire-burst, to realize the parking control of tire burst vehicle.
(2). Lane maintenance and direction controller of tire burst vehicle
i. The environment sensing, positioning and navigating sub controller.
The controller obtains information of road traffic, road signs, road vehicles and obstacles by system of global satellite positioning, vehicle-borne radar, machine vision which include camera of optical electronic and computer processing, mobile communication, or/and vehicle network; based on the information, the controller processes the information, and carries out positioning, driving and navigation to vehicle, and determine distance between the vehicle and the front and rear vehicles, Lane lines, obstacles, relative speed between front vehicle and rear vehicles; the controller makes overall layout of locating of the vehicle and the surrounding vehicles, running environment and running planning.
ii. Path planning sub-controller. Based on environment perception, positioning, navigation and stability control of tire burst vehicle, a control mode and algorithm of wheel, steering and vehicle in normal and tire burst working conditions are used to determine target control value of parameters that include vehicle speed ux, the rotation angle θlr of tire-burst vehicle and rotation angle θe of directive wheel. The mathematics model and algorithm is set up by modeling parameters which include ux, θlr, θe, Ls, Lg, θw, Rs, Si, to formulate position coordinates charts of the vehicles, to plan running paths charts of the vehicle, to determine running routing of the vehicle according to the running charts and running paths. In the parameters, the ux is vehicle speed, θlr is steering angle of tire-burst vehicle, θe is rotation angle of directive wheel, Lg is distance from the vehicle to left vehicles or/and right vehicles, Ls is distance from the vehicle to obstacle or/and vehicle Lane, Lt is distance from the vehicle to front vehicle or rear vehicle or/and obstacle, θw is the orientation angle of the lane that includes the lane line in coordinates, Rs is turning radius of gyration or curvature of running path of lane or vehicle, Si is slip ratio of directive wheel and μi is ground friction coefficient of tire-burst vehicle.
iii. Control decision of sub-controller. Under normal and tire burst working conditions, a coordinated control mode and models of running of vehicle are established by environment identification, positioning of vehicle and lane as well as obstacle, navigation and path planning of the vehicle. The vehicle speed ux, steering angle θlr of vehicle, rotation angle θe of directive wheel and their target control value are determined by relevant parameters and above coordinated control mode and models, to realize coordinated controls of vehicle lane maintenance, path tracking, vehicle attitude, collision avoidance and steady-state control of wheel and vehicle. The mathematical model of ideal steering angle θlr of vehicle and rotation angle θe of directive wheel are established, include:
θlr(Lt,Lg,θw,ux,Rs,Si,μi)θlr(γ,ux,Rs,Si,μi)
θe(Lt,Lg,θw,ux,Rs,Si,μi)θe(γ,ux,Rs,Si,μi)
The modeling structure of the model: the ideal or target control value of rotation angle θlr of vehicles and rotation angle θe of directive wheel are a decreased function to increment of parameters Rs and μi, and is increased function to increment of wheel slip rate Si; the vehicle speed ux is a decreased function with increment of θlr or θe. Based on coordinate positions of lane, surrounding vehicles, obstacles and the tire burst vehicle, the direction and size of control variable θlr and θe of vehicle are determined by parameters including Lg Ls
θw
Rh
ux. Defining three types of deviations of vehicles and wheels. Deviation 1: the deviation eθT(t) between ideal steering angle θlr of the vehicle to path planning, path tracking determined by the central controller and actual steering angle θe′ of directive wheel is defined. The actual steering angle θe′ of the directive wheel contains the steering angle caused by the tire burst rotating moment Mb′ under the condition of tire burst. Deviation 2: the deviation eθlr(t) between ideal steering angle θlr of vehicle and actual steering angle θlr′ of vehicle is defined. Deviation 3: deviation eθ(t) between ideal rotation angle of directive wheel and actual rotation angle θe′ of directive wheel is defined:
e
θT(t)=θle−θe′eθlr(t)=θlr−θlr′
eθ(t)=θe−θe′
A mathematical model of steering vehicle is established by modeling parameters including θlr θe and their deviation eθT(t), eθlr(t) and eθ(t), to determine target control values of steering of vehicle and wheels in real-time. The deviation eθT(t) between ideal steering angle θlr of vehicle and actual steering angle θe′ of wheel can determine sideslip angle and sideslip state of directive wheel. Dynamic control period Hθn of rotation angle of directive wheel is set up, and the equivalent model and algorithm of Hθn are determined by modeling parameters including speed ux and angle deviation eθlr(t) of vehicle. The θe and the θlr are the main control parameters for lane planning, Lane maintenance and path tracking of driverless vehicles.
(3). Drive-by-wire active steering controller of vehicle. The active steering controller is a kind controller by connection of high-speed fault-tolerant bus and management of high-performance CPU control and. The controller adopts redundancy design, and sets up a combination system of directive wheel and drive-by-wire steering of vehicle, and adopts various control modes and structures including steering of front and rear axles or steering of four-wheel by drive-by-wire independently. The combination system sets central control computer of artificial intelligence, dual or triple steering control unit, dual or multiple software, two or three groups of electronic control unit, active steering unit and motors provided with independent structure and combination structure. Based on dynamic system constituted by directive wheels, steering motor, steering device and rotation force of wheel exerted by ground, it are formed that multiple control function loops which include feedback control loops of drive-by-wire steering and steering failure control of vehicle in control. Directive wheel controller and drive-by-wire failure sub-controller are set up. A failure auxiliary steering control of yaw moment produced by differential braking of wheels of braking system is adopted, to realize failure protection of drive-by-wire steering. The x-by-wire bus is used in the controller. The information and data exchange of vehicle-mounted systems are realized by the vehicle-mounted data bus.
i. Active steering control and controller for tire burst. The steering controller of vehicle for tire burst takes vehicle speed ux, steering angle θlr of vehicle, rotation angle θe and rotation driving moment Mh of directive wheel as main control variables. Based on target control values of vehicle speed ux, curvature or steering radius Rh of traffic lane, path and vehicle, steering angle θlr of vehicle and rotation angle θe of directive wheel determined by path tracking control of central controller, it is determined that coordinated or coupled control mode, model and algorithm of two coupled control parameters which include θe and Mh of steering wheel; according to the mode and model of active steering control and the parameters θe and Mh for tire burst, target control value of θe and Mh are calculated under working condition of normal and tire burst. An equivalent model and algorithm of dynamic control period Hθn of steering wheel angle are determined by modeling parameters including speed ux and rotation angle deviation eθlr(t) of vehicle. During each control period Hθn, the target control values of rotation angle θe of directive wheel for vehicle path planning and t path racking are determined by the controller with modeling parameters which include deviation eθT(t) between ideal steering angle θlr of vehicle and actual steering angle θe′ of directive wheel, deviation eθlr(t) between ideal steering angle θlr and actual steering angle θlr′ of vehicle, and angle θe of directive wheel under the condition of vehicle tire burst. Based on deviation values of eθlr−1(t) eθT−1(t) and θe−1 of the previous control cycle Hθn−1, the target control value of rotation angle θe of directive wheel in the period Hθn is determined by the above control model. Define the deviation eθ(t) between ideal rotation angle θe and actual rotation angle θe′ of directive wheel. The rotation angle θe of directive wheel uses closed loop control. In logical cycle of each control period Hθn, the zero value of deviation eθ(t) is taken as the control objective, so that the actual value of directive wheel angle θe′ always tracks the target control value of θe.
ii. Rotary driving moment control and controller of steering wheel of tire burst vehicle. A active steering control and controller of drive-by-wire are adopted. Based on the judgement regulations of magnitude and direction of steering torque and steering angle in coordinate system of active steering of drive-by-wire, two sets independent coupling control system of vehicle rotation angle θlr or/and directive wheel rotation angle θe and rotation drive torque Mh of directive wheel in both sides of zero or origin of directive wheel rotation angle θe are established when left steering and right steering of vehicle, to adapt coordinated control of two parameters of angle θlr and rotary drive moment Mh of vehicle. At the coordinate origin of vehicle steering angle θlr, namely zero point of left steering or right steering of vehicle, the direction of electronically control parameters, which include direction of current or voltage of electric driving device, and rotary direction of motor or translational driving of electric driving device are converted by electronic control unit of controller, to adapt to the coupling or coordinated control between the rotation angle θe and the rotating driving torque Mh. Using rotation angle θe of directive wheel and rotation driving moment Mh of directive wheel exerted by ground as control variables, and based on dynamics equation of steering system, a coordinated control model of rotation driving moment Mh of directive wheel is established by modeling parameters including rotation moment Mk of steering wheel exerted by ground, rotation angle deviation eθ(t) and rotation angle velocity {dot over (θ)}e of directive wheel, to determine the target control value of Mh. The direction of rotation driving moment Mh of directive wheel is determined by deviation eθ(t) between the target control value θe1 and its actual value θe2 of the directive wheel. Defining deviation em(t) between detection value Mb′ of torque sensor and target control value Mh of rotary drive moment of the directive wheel. Open-loop or closed-loop control of rotation driving torque of steering wheel is adopted under condition of tire burst and non-tire burst. In the logic cycle of steering control period Hy, the target control value Mh of rotary drive moment of steering wheel is always tracked by its actual value Mb′ based on the return control of torque deviation em(t). Under action of ground rotation moment Mk and rotation driving moment Mh of steering wheel, the rotation angle θe of directive wheel is controlled by active or adaptive uniting adjustment of driving torque Mh and rotation angle θe of directive wheel at any steering angle position of left side or right side of the vehicle, so that actual value θe2 of steering angle of steering wheel keeps track to its target control value θe1. The driving device of steering system includes a motor or translating device. At the zero position of angle of directive wheel, and when left steering or right steering of vehicle, the rotary driving torque controller of directive wheel makes a one-time conversion to the direction of control parameters including driving torque Mh of directive wheel at the zero position of the angle, or makes a change to the direction of driving current and voltage of directive wheel. In the control of left steering and right steering of vehicle, the steering drive system is constituted by two independent coupling control systems of steering angle θlr of vehicle and driving moment Mh of steering wheel, according to their coordinates. When tire burst occurs, the deviation of rotation angle θe of directive wheel is produced at any steering angle position of rotation angle θe of directive wheel. In the moment of which the directive wheel angle deviation eθ(t) is generated, the active steering controller of drive-by-wire determines the changed direction of the tire burst rotation moment Mb′ and rotation moment Mk of directive wheel exerted by ground, the direction of control direction of rotation angle θe of directive wheel and the driving moment Mh. At the moment of which tire burst rotational torque Mb′ occurs, the torque sensor installed between driving axle of steering system and the directive wheel detects actual rotation driving moment Mh2 of directive wheel in time. Based on a mathematical model of the deviation em(t) between target control value Mh1 of directive wheel rotation driving moment and its actual value Mh2, value of directive wheel rotation driving moment is adjusted in the logic cycle of period Hy of steering control, so that the target control value of rotation angle θe of directive wheel is tracked by its actual value. The direction deviation of directive wheel and vehicle caused by impulse of tire burst rotary moment Mb′ is eliminated or is compensated, to realize stability control of steering of tire burst vehicle.
iii. Path planning, path tracking and safe parking of tire burst vehicle
First. A networked controller of Internet automotive network is set up. Through the global satellite positioning system and mobile communication system, the wireless digital transmission module set by networked controller of vehicle sends signals of position, tire burst status, running and control status of the vehicle to coupling network of the passing vehicles of periphery region. The wireless digital transmission module of the tire burst vehicle can obtain the query information required by the tire burst vehicle, which includes addressing of parking position of the tire burst vehicle and planning path to the parking position by coupling network of the vehicle. Second. A view processing analyzer of artificial intelligence is set up. During running process of vehicle, the processor and analyzer set by the controller classifies and process camera screenshots of surrounding road traffic and environment by category, and temporarily store the typical images, and replace screenshots according to a certain period or/and level, and determine the typical images stored. The typical images stored in the main control computer include emergency parking lane, ramp exiting and parking space of beside road of highway. Based on artificial intelligence, the typical features and abstract features of image obtained. In tire burst control of the vehicle, the tire burst controller set in the networked vehicle uses machine vision recognition or/and networking search mode, and processes and analyzes the images of road and surrounding environment taken by the machine vision in real-time. According to the image features and abstract features, the road image and its surrounding environment image taken from machine vision is compared with the typical classification image of parking location stored in the main control computer. The safely parking position of emergency parking lane, ramp exit or highway side is determined by analysis and judgment of computer. The tire burst vehicle can be driven to the planned parking position, according to the parking line.
(4). Anti-collision control and controller t of driverless vehicle for tire burst
Based on coordinated control mode of anti-collision, braking, driving and stability of tire burst vehicle, the controller is equipped with control modules of machine vision, ranging, communication, navigation and positioning, to determine position of the vehicle, coordinates position from the vehicle to the front, rear, left, right vehicles and obstacles in real time; on this basis, the distance and relative speed between the vehicle and the front, rear, left, right vehicles and obstacles are calculated by control time zone of multiple levels which include safety, danger, no entry and collision. The collision-avoidance, steady-state of wheel and vehicle, and deceleration control of the tire burst vehicle are realized by independence or/and combination control of brake A, B, C, D in logic cycle of period Hh, control mode conversion of braking and driving, coordination control of active steering and active braking. The collision-avoidance control of tire burst vehicle includes collision-avoidance control of the vehicle and front, rear, left right vehicles, and around obstacles. According to the route planned by the controller, path tracking of the tire burst vehicle is carried, to arrive safe parking position of the vehicle.
(5). Failure control of active steering of drive-by-wire for tire burst and no tire burst vehicle and controller. The controller adopts the overall failure control mode. When steering of vehicle driver by man or driverless vehicles fails or lose efficacy, the controller of drive-by-wire steering set by central master controller processes to relevant datum according to a mode, model and algorithm of steering losing efficacy control. The controller outputs signals of unbalanced differential braking of wheels and controls hydraulic braking system (HBS) or the electronic hydraulic braking system (EHS), or the electronic mechanical braking system (EMS), to realize steering failure control by exerting an additional yaw moment to vehicle of drive-by-wire steering, which is produced by differential braking of wheels. Based on vehicle dynamics control system (VDC) or electronic stability program system (ESP), the controller adopts a control modes, models or/and algorithms of wheel steady-state braking A control, balance braking B control, vehicle steady-state braking C control and total braking force D control (shorter form: braking A, B, C and D control). When steering failure control signal iz arrives, the controller take speed ux, ideal and actual yaw angle speed deviation of vehicle, sideslip angle deviation eβ(t) for vehicle quality center, deviation eθlr(t) between ideal steering angle θlr of vehicle and the actual steering angle θlr′ of vehicle, or/and deviation eθT(t) of steering angle of directive wheel and vehicle as main modeling parameters, and adopts several control kinds of logical combination which include A⊂B∪C A⊂C
C⊂A. According to vehicle motion equations which include two freedom or multi degree freedom model of vehicle, the relationship model between rotation angle θe of steering wheel and vehicle yaw angle speed ωr1 is determined at a certain speed ux or/and the ground adhesion coefficient μ. The controller calculates ideal yaw rate ωr1 and sideslip angle β1 of vehicle. The actual yaw angle rate ωr2 of vehicle is measured by yaw angle rate sensor in real time. The deviation eω
A⊂C
C⊂A. Under condition of parallel operation of manual braking operation interface and wheel active differential braking, the failure control of drive-by-wire steering adopts the control logic combination of C⊂A∪B. The brake force in balance braking B control is determined by function model of which the braking force is output from manual brake operation interface. When a wheel enters brake anti-lock control, braking force Qi or one of Δωi
Si of wheel in balance braking B control is reduced in a new braking period Hh+1, until balance braking force of the wheel is 0. According to threshold model, the brake control logic combination A⊂B∪C is adopted when the absolute value of deviation eω
(6). Subroutine or software of steering by drive-by-wire of driverless vehicle
Based on main program of environment perception, positioning, navigation, path planning and control decision-making set in the central controller, the control subroutine of the active steering control of tire burst vehicle is compiled according to the control structure and process, control mode, model and algorithm. The subroutine adopts a mode of a structural design. The subroutine sets program module of direction judgment of relevant parameters of steering angle and steering torque of vehicle. The subroutine sets program modules and coordination control program modules of the steering angle θlr of vehicle, steering angle θe of directive wheel and rotation driving moment Mh of directive wheel to tire burst. The subroutine set up program modules of anti-collision, braking, driving, stability control of wheel and vehicle, or/and failure control of drive-by-wire steering of the tire burst vehicle.
The method adopts a corresponding control mode and model of tire burst driving. Setting the entry conditions of driving control for vehicle tire burst. After tire burst control entry signal ia arrives, the tire burst drive controller of driven by man vehicle or driverless vehicle with auxiliary driving operation interface starts tire burst driving control and send drive control entry signal, according to requirements for tire burst drive control which is identified by driver's characteristic function Wi of vehicle acceleration control willingness or/and collision avoidance control of driverless vehicle. Based on tire burst state and vehicle stability control state, a coordinated control mode, model and algorithm of driving and braking, driving and steering for tire burst are established. The vehicle acceleration {dot over (u)}x and vehicle speed ux is determined. The vehicle enters a coordinated control of driving and secondary stability for tire burs.
(1). Driving control and controller for tire burst vehicle
i. Tire burst drive control for manned vehicle or driverless vehicle with manual auxiliary operation interface. During tire burst control, the characteristic function Wi (Wai Wbi) which shows driver's willingness of acceleration and deceleration control of vehicle is introduced. According to condition and model of self-adapting exiting and returning of tire-burst driving control, the tire-burst control of tire-burst driving controller enters or retreat based on the characteristic function Wi for driver's control intention. The adaptive control model, control logic and logic sequence limited by the condition are established with modeling parameters which include stroke hi of driving pedal and its change rate {dot over (h)}ι. Based on the division of first, second or multiple stroke of driving pedal and the direction division of positive or negative stroke of driving pedal, a control model which includes logic threshold model of active exiting from tire burst braking control, entering of engine driving control and automatic return of tire burst braking control are established. The value of logic threshold model and control logic are set. When tire burst control entering signal ia arrives, and if driving pedal of vehicle is in its one stroke, no matter where driving pedal is located, the engine of vehicle or driving device of electric vehicle will terminate driving output to vehicle immediately. In the two or more strokes of the driving pedal, and when the value determined by the characteristic function Wi reaches a set threshold value, the tire burst braking control exits actively, and vehicle enters driving control limited by condition. In the return stroke of two or more of the driving pedal, and when the value determined by characteristic function Wi reaches set threshold value, the driving control of vehicle exits, and tire burst braking control returns actively. According to the division of first, second and multiple stroke of driving pedal, a asymmetric function model of positive and negative stroke of driving pedal is established by modeling parameters which include driving pedal stroke hi and its derivative
ii. Driving control of driverless vehicle. According to control requirements to acceleration {dot over (u)}x, speed ux and path tracking of vehicle, the central controller of driverless vehicle determines parameter forms of one of driving force Qp of vehicle, comprehensive angle acceleration {dot over (ω)}p or comprehensive driving slip ratio Sp of wheels, and determines algorithm of parameter QP, {dot over (ω)}P or Sp of each wheel. Using equivalent models of relationship between one of parameters Qp, {dot over (ω)}p, Sp and one of throttle opening Dj, fuel injection quantity Qj. One of parameters Qp ωp or Sp are converted to one of throttle opening Dj and fuel injection quantity Qj of fuel engine; from this, one of above parameters is converted to current or/and voltage of the electric drive device of the electric vehicle. When necessary, the conversion of control parameters is determined by the relevant datum of field test.
iii. Self-adaptive drive control for tire burst. One of target control values {dot over (ω)}pk Spk or Qpk of comprehensive angle acceleration ωp of wheels, comprehensive driving slip ratio Sp of wheels and driving force Qp of vehicle is determined by self-adaptive control model. The Qpk is determined by mathematical model with parameters γ and Qp. The {dot over (ω)}pk is determined by the mathematical model with parameters γ and {dot over (ω)}p. The Spk is determined by mathematical model with parameters γ and Sp:
Q
pk
=f(γ,Qp){dot over (ω)}pk=f(γ,{dot over (ω)}p)
Spk=f(γ,Sp)
In formula the γ is tire burst characteristic parameter. The γ is determined by mathematical model with parameters which include collision avoidance time zone tai, vehicle yaw angle velocity deviation eω
γ=f(tai,eω
The modeling structures of models {dot over (ω)}pk and Spk are as follows. The Qpk, {dot over (ω)}pk, Spk are decreasing functions of increment of γ. The γ is an incremental function of decrement of anti-collision control time zone tai, and the γ is an incremental function of absolute value of increment of eω
iv. Allocation in each wheel of one of target control value for control variables Qpk {dot over (ω)}pk and Spk. The Qpk
{dot over (ω)}pk or Spk is allocated to no-burst tire wheel, or two wheels of wheelset of driving axle, or two wheels of steering wheelset. First. The tire burst driving control of vehicle set by a drive shaft and a non-drive shaft. When tire burst of one wheel of driving axle arises, the Qpk
{dot over (ω)}pk or Spk is distributed to the wheelset of driving axle. Under action of differential mechanism of steering axle, two wheels of the wheel pair of driving axle obtain same tire force. When tire burst wheel of steering axle is driven to slip, that is, the parameter value {dot over (ω)}pk1, Spk1 of tire burst wheel is larger than the parameter value {dot over (ω)}pk2 Spk2 of the no burst tire wheel, the driving force provided by the driving axle fails to reach the target control values of Qpk
{dot over (ω)}pk Spk, the tire burst wheel of the steering axle can be braked, so that, values of the {dot over (ω)}pk1 and {dot over (ω)}pk2 of left and right wheels of the driving axle may be equal, or Spk1 is equal to Spk2. The coordinated control model of steering and driving is established to determine the additional angle θp of directive wheel; the insufficient or excessive steering of vehicle, which is caused by applying braking force to tire burst wheel, is compensated, to balance the vehicle instability caused by the braking. When wheel tire burst of non-driving axle, the driving force is allocated to wheelset of the driving axle. For four-wheel vehicle with front and rear drive axles, the driving force is allocated to two wheel of wheel pair of no tire burst drive axle under state of wheel tire burst of one drive axle. Second. Tire burst drive control of electric vehicle. When vehicle sets two driving axles, or when four wheels are driven independently, the driving force exerts on two wheels of no tire burst wheelset; in the same time, the driving force can exert on the no tire burst wheel of the tire burst wheelset, and the driving force of the wheelset produces unbalanced yaw moment Mu1 to mass center of vehicle. The unbalanced yaw moment Mu1 to mass center of vehicle is compensated by unbalanced yaw moment Mu2 produced by differential driving force exerted on the two wheels of no tire burst wheelset. The vector sum of Mu1 and Mu2 is 0. The sum of yaw moment exerting on the vehicle mass center of all wheels is 0, thus, to realize balanced driving for the whole vehicle.
(2) Stability control of driving for tire burst vehicle
The coordinated control mode of driving, braking stability or/and balance control of active steering of tire burst vehicle are adopted.
i. In driving control of tire-burst vehicle, the logical combination A⊂C C or A of braking stability C control of vehicle and wheel braking stability A control are adopted. During the cycle of its logical combination control, the additional yaw moment Mu exerting on mass center of vehicle is formed by longitudinal tire force produced by differential braking or differential driving of each wheel. The Mu is used to balance the tire burst yaw moment Mu′, the unbalancing driving yaw moment Mp or/and the braking yaw moment Mn produced in steering of vehicle; the Mu can be use to compensate insufficient or excessive steering of vehicle, to control the dual instability caused by tire burst of vehicle and control according to normal working of vehicle.
ii. For active steering vehicles, a combined control mode of braking stability and active steering balancing of vehicle is adopted. Based on rotation angle δ of steering wheel or rotation angle θea of directive wheel determined by driverless vehicle, the additional rotation angle θeb of the vehicle is exerted to actuator of the active steering system AFS; the additional rotation angle θeb can be not determined by operation of driver, or by control of driverless vehicle under state of normal working condition. Within critical speed range of vehicle, the unbalanced driving moment Mb′ or/and brake yaw moment Mn produced in steering of vehicle can be compensated by yaw moment produced by additional rotation angle θeb, to balance insufficient or excessive steering of the vehicle. The combined control is especially suitable for vehicles with one driving axle and one steering axle, and is especially suitable for vehicles in which the driving axle and the steering axle are as a same axle. In vehicle driving stability control, the distribution of additional angle θeb of vehicle and the additional yaw moment Mu produced by differential braking or differential driving of each wheel is realized by distribution model with modeling parameters that include longitudinal slip ratio of wheel, or longitudinal slip ratio of wheel and side slip angle of steering wheel, based on the friction ellipse theory model of wheel.
(3). Tire burst driving control subroutine or software
Based on the control structure and process, control mode, model and algorithm for tire burst, the control program or software of tire burst drive of vehicle is developed. The program adopts a mode of structured design. The wheel drive control subroutine includes program modules of control mode conversion between braking and drive for tire burs, self-adaptive drive control of driven by man vehicle, drive control of driverless vehicle and stability drive control for tire burst vehicle.
1). Suspension Lifting Control and Controller
Based on vehicle passive, semi-active or active suspension system, a coordinated control mode, model and algorithm of suspension are established by using modern control theory and corresponding algorithms, such as ceiling damping, PID, optimum, self-adaptive, neural network, sliding mode variable structure or fuzzy control for tire burst and normal working condition. The target control value of elastic element stiffness Gv of suspension, damping Bv of shock absorber, position height Sv of suspension are determined by the control mode, model and algorithm. Second judgment model of suspension control for tire burst is established. The model includes threshold models of single parameter or multi parameter. When tire burst control entering signal ia arrives, the second judgment of suspension control is made by the main and secondary threshold model. Based on secondary threshold model, the controller outputs the second starting or entering signal iva or exiting signal ive for the tire burst suspension control, to realize the conversion of suspension control mode of normal and tire burst condition.
(1) Suspension Lifting Control
i. Entering and exiting of suspension lifting control for tire burst. The controller sets a threshold model with modeling parameters of tire pressure pr(pra pre) or effective rolling half-way Ri of wheel, lateral acceleration {dot over (u)}y. A threshold (value) av (av1
av2) of threshold model is determined. After the tire burst control entering signal iva arrives, and when the pra or Ri reaches the main threshold av1 and the {dot over (u)}y reaches the sub-threshold av2, or {dot over (u)}y reaches the main threshold av2 and pre reaches the sub-threshold av1, or one of the pra and the {dot over (u)}y reaches the corresponding threshold av1 or av2, the vehicle enters tire burst suspension control. The electronic control unit set by the controller sends out the suspension control entering signal iva for tire burst; otherwise the exiting signal ive of tire burst control is output, the suspension control of tire burst exits. The av2 is determined by model with parameters which include half distance Lv2 between front and rear axles of vehicle, half wheelbase of front or rear axles half-spacing Lv1, the vehicle centroid height hk and the vehicle rollover angle γd of tire burst.
When vehicle enters real control period or inflection control period for tire burst, the threshold value av2 is adjusted by the coefficient K.
ii. Suspension lifting controller. A coordinated control modes of Gv Bv and Sv are established by the controller with control variable of suspension displacement Sv, shock absorption resistance Bv and suspension stiffness, to determines target control values of Gv
Bv and Sv of tire burst wheel. According to the modes, the amplitude and frequency of suspension in the vertical direction of vehicle body are calculated. The pneumatic or/and hydraulic spring suspension adopts pneumatic or/and hydraulic power source, and servo pressure regulating device
First. According to the coordinated control mode of control values Gv Bv and Sv, corresponding mathematical models of the Gv
Bv and Sv is established respectively by modeling parameters which include input pressure pv, or/and flow Qv, load Nzi of the regulating device, and include damping coefficient kj of throttle opening of liquid flow between working cylinders of shock absorber, fluid viscosity vy, suspension displacement Sv and the displacement velocity {dot over (S)}v and acceleration {umlaut over (S)}v, and the velocity and acceleration velocity of fluid flowing through throttle valve, and elastic coefficient kx of spring suspension:
S
v
=f(pv,Nzi,Gv),Sv=Sv1+Sv2+Sv3
B
v
=f({dot over (S)}v,{umlaut over (S)}v,kj,vy),Gv=f(kx,pv) or Gv=f(kxb,hv)
In the formula, the Sv1 is static position height parameter of suspension, the Sv2 is position height adjustment parameter for normal working condition, the Sv3 is position height adjustment parameter of suspension for tire burst, the kx is elasticity coefficient of spiral spring, the hv is elastic deformation length of spiral spring. The regulating value Sv3 is determined by the function model with the parameters which include effective rolling radius Ri or tire pressure pra of tire burst wheel:
S
v3
=f(Ri)Ri=f(pra)
When the suspension travel position is adjusted by using pneumatic or hydraulic lifting devices, the relationship model are established by the parameters which include the input pressure of the hydraulic cylinder pv or/and the flow Qv, the position height of independent suspension travel Sv and the load Nzi of hydraulic cylinder or/and air bag of adjusting device:
N
zk
=f(Sv,pv,Qv)
The target control value of the suspension position height Sv of each wheel is converted to the input pressure pv or/and flow Qv of the adjusting device. In the formula, Nzk is the dynamic load of tire burst vehicle. The Nzk is sum of each wheel load Nzi for tire burst vehicle under normal working conditions and load variation value ΔNzi of tire burst wheel:
N
zk
=N
zi
+ΔN
zi
The value of load variation ΔNzi is determined by the equivalent function model between the effective rolling radius Ri or tire pressure and ΔNzi of the wheel:
ΔNzi=f(Ri) or ΔNzi=f(pra)
In order to simplify the calculation, the characteristic functions with parameter of tire burst load variation ΔNzi and the tire pressure pra are determined by the test. The load Nzi and its variation ΔNzi of each wheel under condition of tire burst are determined. Setting the load Nz0 of wheel under the normal working condition of the wheel, the load variation value ΔNzi in dynamic test is detected under states of the decreasing series value Δpra of tire pressure for the wheel or the effective rolling radius ΔRi of wheel. A datum sheet is established by the characteristic functions with the parameters Δpra or ΔRi and ΔNzi. The datum sheet are stored in the electronic control unit. In the tire burst control, the value of ΔNzi can be taken out by input parameters of pra or ΔRt. The value of ΔNzi can is acted as the calculated parameter value. Delimiting the deviation ev(t) between measured position height Sf of suspension and the target control value Sv, the position height of tire burst wheel or/and position height of each wheel is adjusted by feedback control of deviation ev(t). The balance of vehicle body and load balance distribution of the tire burst vehicle are maintained by adjusting the height of position of suspension.
Second. Suspension travel Sv, shock absorption resistance Bv and stiffness Gv coordinated controller. The coordinated control models of the control variables Gv Bv and Sv of suspension are established:
S
v(Gv,Bv)
The target control values of {dot over (S)}v and {umlaut over (S)}v are suitable for the shock absorption resistance Bv control of hydraulic damper suspension. For suspension with magnetorheological fluid damper, the shock absorption resistance Bv is adjusted to a lower constant. A hydraulic shock absorber is composed in suspension of gas or hydraulic pressure spring. Under certain conditions of which travel Sv, velocity {dot over (S)}v and acceleration {umlaut over (S)}v of suspension or damping piston of absorber are determined, the shock absorption resistance Bv of the hydraulic absorber is determined by the opening degree of the damper valve and fluid viscosity of the damper. A magnetorheological (MR) damper is combined in the pneumatic or hydraulic spring suspension. Under the condition of which the opening of the damper valve is fixed, the shock absorption resistance Bv can be adjusted by controlling viscosity of electronically controlled MR.
(2). Suspension control program or software for tire burst
Based on the structure, flow, control mode, model and algorithm of suspension lifting control for tire burst, a tire burst suspension lifting control subroutine is developed. The subroutine adopts a structured design. The program sets suspension control program modules which include secondary entering of suspension control of tire burst vehicle, the conversion of tire burst and non-tire burst control modes, travel Sv control of wheel suspension, coordination control of Gv Bv and Sv of wheel suspension, and program module of servo control for input parameters which include pressure pv or/and flow Qv of adjusting device for suspension travel.
The method has the following technical characteristics and advantages which are compared to the existing technology. The method adopts a new concept and technical scheme of tire burst control for vehicles. The new concept and technical scheme covers the main key technologies of tire burst control for driven by man vehicles and driverless vehicles. This technology includes the “double instability” control for tire burst vehicles. The method defines and establishes a determination mode of tire burst by detecting tire pressure of tire pressure sensor, characteristic tire pressure and state tire pressure. Based on the real tire burst point, inflection point of tire burst, controls singularity and time zone of collision-proof control in the process of tire burst control, the method make the tire burst control adapt to the process of tire burst state process in logical cycle of control period, to realizes phasing, processing and control time zoning of tire burst control. The method adopted mechanism of tire burst control entering and exiting, control mode conversion between normal conditions and burst conditions, the self-adaptive control modes of tire burst for wheel and vehicles. Modes of active control, state control and man-machine exchange control are established. In this method, the main control of tire burst, engine braking, braking of brake device, throttle opening or/and fuel injection of engine, rotation moment of steering wheel, active steering, suspension lifting controller of tire burst are set up. Based on the type and structure of control, the corresponding control module are set up. The coordinated control modes and models of vehicle braking, driving, steering, steering wheel rotation force and suspension are set up by means of on-board data bus and special data bus of X-by-wire for tire burst, to realize tire burst control in normal working and tire burst condition, and real or non-real tire burst process. The tire burst control concept adopted in this method is novel, and the technical scheme is mature; under condition of rapid change of tire burst state process of vehicle, movement states of tire burst wheel and running attitude of vehicle, the important technical barriers that include severe instability of wheel and vehicle, and controlling difficulty of extreme state for vehicle tire burst are broken through; therefrom it is solved that the important technical topic which has puzzled by safety of vehicle tire burst for a long time.
1). Control Mode, Structure and Process of Vehicle Tire Burst. See
The master controller 5 of tire burst takes parameter signals 1 of wheel and vehicle, signals 2 of state parameters for front and real vehicle or/and the parameters signals of environment perception and route planning of driverless vehicle, the parameter signals 3 of tire burst control, output parameter signal 4 of vehicle braking, driving and steering of manual operation interface, and parameters signal I 16 of manual key control as input parameters signals, and controls tire burst of vehicle according to the signals of tire burst control parameter. The relevant parameters are calculated on basis of the mode, model and algorithm for tire burst control. Tire burst mode recognition of state tire pressure and characteristic value for tire burst are determined; judgement of tire burst, division of control stages for tire burst and control, control mode conversion for tire burst are completed; coordinated control of multiple controllers, manual operation and active control for tire burst can be realized. According to status process of tire burst, definition of tire burst and judgment mode, tire burst is determined by master controller 5; master controller 5 output tire burst signal I 6. The tire burst signal I 6 output by master controller 5 inputs converter 8 of control modes directly or by date bus. The converter 8 realizes conversion of control modes between normal working condition and tire burst working condition. The tire burst controller 7 of wheel and vehicle obtains the parameter signals directly from the relevant sensors or from the main controller 5 of the tire burst. Based on the on-board system, and under the coordination of the main controller 5, the controller 7 enters the independent parallel control or the joint coordinated control, to make the system enter the inner cycle of tire burst control. In inner cycle control and according to mode model and algorithm of throttle opening control or/and fuel injection control, the engine throttle controller 9 or/and fuel injection controller 10 close throttle or dynamically adjust throttle opening, and terminate or dynamically adjust fuel injection of fuel injection controller 10; throttle and fuel injection controller 9 and 10 achieve jointly engine drive control 22. According to the coordinated control mode, model and algorithm of tire burst active braking and vehicle collision avoidance, the vehicle braking controller 11 adopts wheel steady state braking, vehicle balanced braking, vehicle steady state braking and total braking force (A), (B), (C), (D) control, and adopts their logic combination and logical cycle of control, to realize vehicle steady deceleration and vehicle state control. Based on the power steering system, the rotary force controller of steering for tire burst vehicle realizes the dual controls of the power assistant steering or resistance steering for tire burst at any angle of the steering wheel, according to the control mode, model and algorithm of steering wheel rotation angle, steering assistant moment or rotation torque of steering wheel for tire burst. According to control mode, model and algorithm of active steering for tire burst, the active steering controller 13 exerts an additional angle to steering wheel, to balance tire burst steering angle of vehicle. The rotation force controller 12 of steering wheel and active steering controller 13 of tire burst vehicle jointly realize active steering control 23 of tire burst vehicle. Suspension lifting controller 14 adopts coordinated control mode, model and algorithm of travel, damping and stiffness of suspension. The tilting or probability rollover of vehicle after tire burst is reduced by adjusting suspension lifting, and the load of each wheel is balanced. Tire burst control parameter signal 3 of vehicle is returned to tire burst master controller 5 by control feedback line. The engine brake controller 15 of system is set up. The brake control by engine is mainly suitable for the pre-tire burst period. The master controller 5 specially set manual control key to exiting of tire burst control or returning; the controller outputs the parameter signal I 6; signal I 6 is input the master controller 5 through control line; the manual keying control logic covers the active control logic of tire burst. By means of three man-machine operation interfaces of braking, driving and steering control of vehicle, the self-adaptive control of man-machine exchange is realized. The self-adaptive control logic of human-computer exchange covers conditionally the active control logic of tire burst of vehicle. Under normal working conditions, the on-board controller can obtain the parameter signals directly from relevant sensors, or/and the master controller 5 or/and the control mode converter 8 through the data bus 21; the on-board controller can control the corresponding braking, driving, steering and suspension execution devices 17 according to control modes of normal working conditions, to realize outer cycle of control of on-board system. The output signals of tire burst master controller and controller of on-board system input corresponding braking, driving, steering and suspension execution device 17 through control mode converter 8, to realize the vehicle control inner cycle under working condition of tire burst.
The tire burst pattern recognition and tire burst judgement of vehicle are based on wheel state, steering state of vehicle and vehicle state. According to tire burst pattern identification and types of running state and structures of vehicle, which include non-braking and non-driving, driving and braking, tire burst judgement conditions and models which include the tire pressure pre [xb, xd] are adopted. A judgement logic for tire burst is establish to realize tire burst pattern recognition and tire burst judgment. The three types of running state and structure of vehicle are expressed by positive (+) and negative (−) of mathematical symbols.
(1). The structure of non-braking and non-driving state of vehicle is characterized by positive (+) and negative (−). The judgment logic for tire burst is established in the state. In the state process, pressure pre1 is determined by the equivalent mathematical model and algorithm. The mathematical model is established by modeling parameter including yaw angle velocity deviation eω
p
re1
=f(e(ωk),eβ(t),eωNzi
δ)
In process of the state, the braking force Qi and driving force Qp are zero. The deviation e(ωk) of non-equivalent relative angle velocity ωk and deviation e({dot over (ω)}k) of non-equivalent relative angle acceleration or deceleration {dot over (ω)}k are equal to, or are equivalent to, equivalent relative parameter deviation e(ωe) and e({dot over (ω)}e), under condition of which parameter values of μi Nzi
δ
Qi taken by two wheels of balance wheelset are equal or equivalent equal. In the same parameters set E(λi μi
Nzi
δ
Qi), values of λi taken by the two wheels of the balance wheelset can be taken as 0 or 1, and e({dot over (ω)}k) can be replaced by non-equivalent relative slip rate deviation e(Sk). Based on state tire pressure pre1 and threshold model for tire burst judgement, the absolute value of non-equivalent relative angle velocity deviation e(ωk) in balancing wheelset for front and rear axles is compared. The wheelset of which bigger absolute value of deviation e(ωk) is taken in the two balance wheelset is tire burst balancing wheelset, and the wheel of which bigger ωk value is taken in two wheels of the balance wheelset is tire burst wheel. Under condition of non-braking and non-driving of vehicle, the wheels are in free rolling state, thus the correction coefficient λi is determined by model with modeling parameters of μi
Nzi and δ. Wheels can be in state of rolling freely without braking and driving. After λi is corrected equivalently, the equivalent and non-equivalent relative angle velocity, angle acceleration and deceleration of left wheel and right wheel are basically equal.
(2). Driving state structure (+). In the state, for the non-driving axle wheelset and the driving axle wheelset, the equivalent mathematical model of state pressure pre is established by modeling parameters which include yaw angle velocity deviation eω
p
re2
=f(eω
p
re2
=f(eω
λi=f(μiNzi
δ)
Under condition of which load Nzi of left wheel and right wheel change is little, the ground friction coefficient μi of the left wheel and right wheel is equal and the rotation angle δ of steering wheel is small, the compensation coefficient of Ai can be taken as 0 or 1. The left wheel and right wheel of balancing wheelset for non-driving axle adopt non-equivalent relative angle velocity deviation e(ωk) and angle acceleration and deceleration deviation e({dot over (ω)}e). The equivalent relative angle velocity deviation e(ωe) and angle acceleration and deceleration deviation e({dot over (ω)}e) are used in the left and right wheels of the drive axle. Under condition of the ground friction coefficient of left and right wheels is equal, and the driving moment Qui of left and right wheels of driving axle is equal, the deviation e(ωe) and e(ωk), e({dot over (ω)}e) and e({dot over (ω)}k) of left and right wheels are equivalent or equivalent equal, thus λi can be taken as 0 or 1. The state tire pressure pre2 is compensated by λi under the condition of which friction coefficient μi of the left wheel and right wheel is different. The tire burst judgement is made by threshold model of state tire pressure pre2. After tire burst is determined, the equivalent relative angle velocity ωe of the left wheel and right wheel of the driving axle is compared. Based on the state tire pressure pre2 and the tire burst judgement threshold model, the non-equivalent relative angle velocity ωk of left wheel and right wheel of non-driving axle is compared, and the equivalent relative angle velocity ωe of left wheel and right wheel of driving axle is compared. The wheel with bigger value of ωe and ωk in two wheelsets of driving axle and non-driving axle is tire burst wheel, and the balance wheelset of which larger value of e(ωe) is taken in the two axles is tire burst balance wheelset. During the real tire burst time and inflection point time for tire burst, driving of the vehicle has be exited actually under condition of which vehicle has be not implemented control of anti-collision.
(3). Braking state structure (+). The parameter of rotary moment deviation eM
p
re3
=f(eωλi=f(μi
Nzi
δ)
Where, the e(Qk) is the non-equivalent relative braking force deviation of the balanced wheelset. When the steering angle of directive wheel is small, and the load Ni of vehicle varies slightly, and the friction coefficients of left and right wheels are equal, or is deemed to be equal, the value of λi can be taken as 0 or 1. Under condition of which friction coefficient μi of the left wheel and right wheel is different, and steering angle δ and load transferred by wheels is smaller, the λi is determined by equivalent correction model with parameters of μi, Nzi and δ of left wheel and right wheel; the non-equivalent angle velocity deviation e(ωk) and non-equivalent angle deceleration deviation e({dot over (ω)}k) of the left wheel and right wheel of the two axles are actually equivalent to equivalent relative angle velocity deviation e(ωe) and angle deceleration deviation e({dot over (ω)}k) under the condition of which the braking force Qi of the left and right wheels of the two axles is equal. After tire burst is determined, absolute values of e(ωe) and e(ωk) of front axle and rear axles are compared based on state tire pressure pre3 and threshold model of tire burst judgement; the wheel that takes a bigger absolute value of ωe or ωk is tire burst wheel, or the positive and negative sign of e(ωk) and e(ωe) can be used to determine tire burst wheel. The balanced wheelset with tire burst wheel is tire burst balanced wheelset. The braking state structure 2. The state structure is a state structure of which tire burst vehicle enters steady state control for differential braking of the wheels. In this state structure, two ways are used to determine state tire pressure pre. First way. The way is based on “braking state structure 1”, to determine state tire pressure pre41, that is, the pre3 is equal to the pre41, then to determine tire burst of vehicle. Second way. For vehicle of which parameters of wheel braking force Qi and angle velocity ωi are taken as control variables, the state tire pressure pre41 is calculated under the condition of differential braking of wheels. The first algorithm of pre4 is based on judgment of tire burst of “the braking state structure 1”; the two wheels of tire burst balancing wheelset are exerted by equal braking force; the following calculation model of determining state tire pressure pre41 is adopted; when the left wheel and right wheel of tire burst balancing wheelset are exerted by equal braking force Qi, one of the same parameters in En is Qi, it satisfies the condition of same braking force Qi taken by two wheels of tire burst balancing wheelset, and effective rolling radius Ri of two wheels of tire burst balancing wheelset is regards as a same; from this, the e(ωk) is equivalent to e(ωe). Under state of which differential braking of two wheels of non-tire burst balanced wheelset is carried by the following calculation model of pre42, the same parameters in the set En are taken as Qi and Ri, the parameters e(ωe) and e({dot over (ω)}e) in calculation model of pre42 simultaneously satisfy the condition of which the values of Qi and Ri of each wheels are equivalent or equivalent equality. Algorithm 2 of state tire pressure pre4. The unbalanced braking force of steady-state control of differential braking for vehicle is applied to two wheels of balanced wheelset of tire burst and no tire burst. The calculation model of pre43 is adopted as follows.
p
re41
=f(eω
p
re43
=f(eωNzi
δ)
Under the state in which same parameter Ri of each wheel in the set En is set, The parameters e(ωe) and e({dot over (ω)}e) should satisfy the conditions of which braking force Qi and the effective rolling radius Ri of two-wheel of balanced wheelset are equivalent or equivalent equality, and the e(Qe) in calculation model of pre43 may be replaced by the non-equivalent relative braking force deviation e(Qk) of two-wheels of balanced wheelset, and the “abnormal change” of vehicle yaw angle velocity deviation ea, (t) in tire burst control is compensated by change of parameter e(Qk). Among them, the λi is determined by the equivalent model with parameters μi Nzi and δ of left wheel and right wheel. In the above formulas, equivalent relative angle deceleration deviation e({dot over (ω)}e) can be interchanged with equivalent relative slip rate e(Se). The tire burst is determined by state tire pressure pre and the value of the tire burst threshold model. The absolute values of e(ωe) of the front axle and rear axle are compared after the tire burst is determined, and the balance wheelset of which the larger absolute value of e(ωe) is taken in the two axles is tire burst balance wheelset. The wheel of which the larger absolute value of e(ωe) or e(ωk) is taken are tire burst wheel. In the balancing wheelset for tire burst, the positive and negative sign of e(ωk) also is used to determine the tire burst wheel and tire burst balanced wheelset. When rotation angle δ of steering wheel is Larger, and ground friction coefficient μi for two wheels of left and right is set to be equal, the rotation turning radius of the vehicle is determined by parameters such as rotation angle δ of the steering wheel, vehicle speed ux or/and side deviation angle αi of steering wheel; from this, it is determine to deviation of running distance and rotating angle velocity deviation Δω12 of left wheel and right wheel. According to Δω12 or the variation value of load of left wheel and right wheel of vehicle, the correction factor λi is determined by the function model with Δω12 or/and variable value ΔNz12 of load of wheel left wheel and right. In order to simplify the calculation of correction factor λi, the load transfer ΔNz12 of two-wheel of front axle and rear axle can be neglected; the functional relationship between correction factor λi and variable δ, parameter ux is determined by field test, and the numerical chart of functional relationship is compiled. The numerical chart is stored in electronic control unit. In braking control, the λi is checked and called by using main parameters including ux, δ and μi. The value of parameter λi is used to determine equivalent parameter values of Left and right wheels of front axle and rear axle and state tire pressure pre.
(1). Based on the origin rules of rotation angle δ and rotation torque Mc coordinate of steering wheel, the rules of rotation direction for Left and right angle δ, the rules of direction positive (+) negative (−) of rotation torque Mc and increment or decrease ΔMc of Mc of steering wheel, and the rules of positive (+) negative (−) direction of tire burst rotation moment and steering assist moment Ma, it can be established to the judgment logic of positive (+) and negative (−) direction of burst tire rotation moment and steering assistant moment Ma when steering wheel or directive wheel turns to right or to left, Mb′ or when it is in right-handed rotating. The judgment logic can be shown by the following logic chart of judgement mode of steering angle and torque direction. According to the logic chart of the judgment logic, the direction of burst tire rotation moment Mb′ and the steering assistant moment Ma can be determined. Direction determination of tire burst use the following model or their joint model.
The Direction determination mode of angle and torque: right-hand rotating logic chart
of direction of rotation angle δ.
The direction judgement mode of rotation angle and rotation torque: left-handed logic diagram chart of angle δ can be omitted in this article. Based on the origin regulation of steering wheel angle δ and torque Mc, and when rotation angle δ of the steering wheel or the rotation angle θe of directive wheels is in left turning, the positive (+) and negative (−) regulation of steering wheel torque or the positive (+) negative (−) regulation of torque measured by sensor are contrary with the positive (+) and negative (−) regulation of right turning of steering wheel. According to the rules of positive (+) negative (−) of left-hand turn of steering wheel, the logic of the direction judgement of tire burst moment and steering assistant moment Ma can be established when the rotation angle δ of steering wheel is left-handed rotating. Except for the rotation direction of angle δ of steering wheel and positive (+) negative (−) rules adopted by the steering wheel which is in left-handed turn are different to right turn, the parameters, structure, judgement flow and method used in direction judgment logic and logic chart of tire burst rotation moment and steering assistant moment Ma are same as those used in right turn of steering wheel.
(2). The direction determination mode of rotation angle. Based on the origin rules of steering wheel angle δ and torque Mc, the rules of left or right rotation of angle δ of steering wheel and angle of directive wheel, the positive (+) and negative (−) rules of absolute angle δ that is measured by two sensors set on the rotation shaft of steering system to non-rotating reference system of vehicle, positive (+) and negative (−) rules of angle difference Δδ, the positive (+) and negative (−) rules of direction of tire burst rotation moment Mb′ and the steering assistance moment Ma, it is determined to the positive (+) and negative (−) of rotation angle difference Δδ. the positive (+) and negative (−) of Δδ indicate the positive (+) and (+ negative (−) of rotation direction of steering wheel rotation torque Mc; the judgement logic of direction of tire burst rotation torque Mb′ and steering assist moment Ma are determined when steering wheel or directive wheel turns to right. The judgment logic can be represented by the following logic diagram of “direction judgment mode of steering angle”. According to the logic diagram, the direction of tire burst rotation moment Mb′ and the direction of steering assistance moment Ma are determined. Based on detection signal of two sensors set on rotation shaft of steering system, two relative coordinate systems of steering wheel angle δ, which is set in steering system, are adopted; direction of angle and torque of steering wheel or directive wheel, direction of tire burst rotation moment Mb′ and steering assistance moment Ma are determined by the direction Judgement mode of steering angle for tire burst.
The direction Judgement mode of angle: Logic chart of steering wheel right rotation with positive difference Δδ
The direction judgement mode of rotation angle. The left-hand logic diagram of steering wheel is omitted in this article. Based on the origin regulation of steering wheel angle δ and torque Mc, and when rotation angle δ of the steering wheel or turning angle θe of directive wheels is in left turning, the positive (+) and negative (−) rule of steering wheel torque or the positive (+) negative (−) regulation of torque measured by sensor are contrary with the positive (+) and negative (−) rule of right turning of steering wheel. According to the rules of positive (+) negative (−) of left-hand turn of steering wheel, the logic of direction judgement of tire burst rotation moment and steering assistant moment Ma can be established when the turning angle δ of steering wheel is left-handed rotating. Except for it is different to the rotation direction of the steering wheel angle δ and positive (+) negative (−) rules adopted by the steering wheel which is left-handed turn, the parameters, structure, judgement flow and method used in direction judgment logic and logic chart of tire burst moment and steering assistant moment Ma in left turning of steering wheel are same as those used in right turn of steering wheel.
(3). In the above tables, it is indicated that vehicle is in normal working condition, or wheel is not in tire burst state, when the rotation moment Mb′ of tire burst is 0. Whether there is a tire burst which can be determined by the positive (+) or negative (−) of the tire burst rotation moment Mb. When tire burst rotation moment Mb′ is positive (+), it is indicates that the direction of Mb′ is consistent with the direction of the positive route of steering wheel angle δ, and the direction of steering assistant moment Ma is consistent with the direction of the negative route of steering wheel angle δ. When tire burst rotation moment Mb′ is a negative (−), it indicates that the direction of Mb′ is consistent with the direction of the negative route of steering wheel angle δ, and the direction of steering assistant moment Ma is consistent with the direction of the positive route of steering wheel angle δ. When increment ΔMc of steering assistant moment Ma is 0, it indicates that the rotation force Mk of steering wheel exerted by ground is in a force balance state, and it indicates that derivative Mfc of parameter Mk is 0.
(4). Mode of indirect determination of tire burst direction. In the control of tire burst rotation torque, the dynamic characteristics of indirect judgment of tire burst direction are not ideal.
i. The indirect direction judgment of tire burst rotation moment Mb′ use a mode of position of tire burst wheel and the field test. When tire burst of wheel of front axle occur, the direction of tire burst rotation moment Mb′ points to direction of same side of the tire burst position. On the same way, for tire burst of wheel of rear axle, the direction of rotation moment Mb′ for tire burst can be determined by the position of tire burst wheel, the direction of rotation angle of steering wheel and field test.
ii. Determining of direction of the tire burst rotation moment Mb′ adopt yaw judgement model of vehicle. After tire burst of vehicle occur, the understeering of the left turning of vehicle and the oversteering of the right turning of vehicle can indicate that tire burst of right front wheel occur, the understeering of right turning vehicle and the oversteering of left turning vehicle indicate that tire burst of left front wheel occur. According to direction of rotation angle δ of steering wheel and the understeering or oversteering of vehicle, the direction of tire burst of rear wheel and direction of tire burst rotation torque Mb′ of steering wheel can be determined also.
4).
The tire burst braking control of this method adopt wheel braking steady A, vehicle stability braking C, wheel balanced braking B and total braking force D control, as well as their logical combination control. The A, B, C, D control and their logical combination control for tire burst braking can realize compatibility control with vehicle stability control (VSC), vehicle dynamics control (VDC) or electronic stabilization program system (ESP). The tire burst braking control takes one or more modeling parameters of angle deceleration {dot over (ω)}i, slip rate Si of wheel, vehicle deceleration {dot over (u)}x and braking force Qi as control variables; the control of tire burst brake can be realize in the logic cycle of period Hh for control of A, C, B, D and its combination control. In its dynamic control for tire burst, the braking C control should be used in priority.
(1) Steady-state braking A control of wheels. The braking A control include steady-state braking control of tire burst wheel and anti-lock braking control of no tire burst wheel. In normal working conditions, slip rate Si of tire burst wheel do not have the specific meaning of peak value slip rate of anti-lock braking control. When tire burst control entering signal ia arrives, the braking controller terminates or reduce the braking force exerted to tire burst wheel, it can make tire burst wheel be in a pure rolling state without braking, or be in steady-state braking A control for tire burst wheel, according to one of the parameter form of control variable {dot over (ω)}i, Si and Qi for braking A control. In the control of tire burst braking A, the braking force of tire burst wheel is decreased in step by step on equal or unequal value, based on characteristics of the motion state of tire burst wheel. The brake A controller take {dot over (ω)}i and Si as control variables and control objectives, and takes brake force Qi as parameter variables; A mathematical model is established by the control variables and modeling parameters, to determine control structure and characteristics of braking A control by certain algorithm. Under braking A control, tire burst wheel and no tire burst wheels can obtain a dynamic and steady-state braking force. A general analytic mathematics formula can be adopted by the model of braking A control, or it can transformed into expression of state space, and the dynamics system of wheel is expressed by state equation. On this basis, the appropriate control algorithm is determined by applying modern control theory. Braking control period Hh of tire burst is obtained. In process of logical cycle of period Hh, the braking force Qi is reduced step by step according to the characteristics of the movement state of the tire burst wheel, and reduction of braking force Qi of tire burst wheel can be realized by the reducing of target control values {dot over (ω)}ki and Ski of control variables ωi and Si, until {dot over (ω)}ki and Ski achieve a set value or zero. During the control process, the actual values ωi and Si of tire burst wheel fluctuate around their target control values {dot over (ω)}ki and Ski. The braking force Qi is decreased gradually, equally or unequally to 0, thus indirectly adjusting the braking force Qi of wheels.
(2) Braking stability C control of vehicle
According to parameter forms of one of angle deceleration {dot over (ω)}i or/and slip rate Si, vehicle additional yaw moment Mu of brake C control is used to direct or indirect distribution of braking force of each wheel. The distribution of additional yaw moment Mu of brake C control for wheels can be expressed as follows. According to brake C control mode and model, and on basis of position relationship of tire burst wheel, yaw control wheel and non-yaw control wheel the efficient yaw control wheel and yaw control wheels are determined by quantitative relationship of which additional yaw moment Mu is vector sum of additional yaw moment Mur determined by longitudinal differential braking of wheels and additional yaw moment Mn of braking in steering; the distribution of additional yaw moment Mu under straight and steering state of vehicle is determined by the efficient yaw control wheel and yaw control wheels. The additional yaw moment Mu is not allocated to the tire burst wheel. The allocation models of Mu can adopt one of single wheel, two wheel and three wheel models or their combination, according to the states of vehicle in normal and burst working conditions.
i. Under braking in straight running state of vehicle, the Mu is equal Mur. The Mur is additional yaw moment produced by longitudinal differential braking of wheels. The Mu is distributed according to coordination distribution model of single wheel, two wheel or three wheel. In the single wheel or two wheel, the Mu can be allocated to any one or two of the yaw control wheels.
ii. Under braking in steering state of vehicle, allocation of additional yaw moment Mu to wheels adopts single wheel, two wheel or three wheel mathematical model, a. The allocation model of two wheel is as following. For vehicle of which front axle is steering axle, the allocation model of additional yaw moment Mu of wheels is established by modeling parameters which include additional yaw moment Mur determined by longitudinal differential braking force of wheels, additional yaw moment Mn determined by braking in vehicle steering, slip rate Si, rotation angle δ of steering wheel or rotation angle θe of directive wheel and Load Mzi of yaw control wheels. Based on the allocation model of additional yaw moment Mu, the allocation of Mu to three yaw control wheels can be determined. A variety of yaw control modes can be formed by different combinations of three yaw control wheels. First, for tire burst of right front wheel in state of right-turning of vehicle, the left front wheel can be determined as efficiency yaw control wheel, according to vector model with modeling parameter Mu that includes Mur and Mn, load Nzj of each wheel and their transfer amount ΔNzi which shifts to left rear wheel and left front wheels in tire burst; when direction of Mur and Mn is same, the maximum value of additional yaw moment Mu is achieved under condition of certain differential braking force. For two yaw control wheels of left front and left rear, the distribution proportion of Mu is determined in the process of braking and steering. The distribution model of two yaw control wheels of left front and left rear is established by modeling parameters which include braking slip ratio Si of left front wheel and left rear wheel and rotation angle θe of directive wheels. Based on the model, the distribution of additional yaw moment Mu of the two yaw control wheel is realized. The steering of vehicle, longitudinal slip ratio Si and lateral slip angle of two yaw control wheels for left front wheel and left rear wheel are controlled by the distribution of additional yaw moment Mu between two yaw control wheels. The tire burst yaw moment Mu′ produced by tire burst of right front wheel is balanced by Mur and Mn, therefrom, Insufficient or excessive steering of vehicle is balanced or eliminated. Second, tire burst of left front wheel under state of right-turning of vehicle. According to vector model with modeling parameter Mu that includes Mur and Mn, the Mu can achieve maximum value when the direction of Mur and Mn is same; the right rear wheel is determined as the efficient yaw control wheel. Based on the load Nzi of each wheel and their transfer amount ΔNzi which is shifted to right rear wheel and front wheel in tire burst state, the distribution model of two yaw control wheels is established by parameters which include the rotation angle θe of right front wheel, side or transverse slip angle and longitudinal slip ratio Si of right front wheel and longitudinal slip ratio Si of right rear wheel, and load Nzi of each wheel. Based on this model, the distribution of additional yaw moment Mu between two yaw control wheels is realized; the steering of vehicle and slip rate Si of right front and right rear wheel are also controlled at the same time. The tire burst yaw moment Mu′ produced by tire burst of left front is balanced by Mur and Mn, thus, Insufficient or excessive insufficient steering of tire burst vehicle is balanced or eliminated by Mur, Mn and their superposition. Third, the tire burst of right rear wheel in state of right-turning of vehicle. According to the vector model of Mu including Mur and Mn, The additional yaw moment Mu of vehicle achieves the maximum value when direction of Mur and Mn are same; the left rear wheel is efficient yaw control wheel, and the left front wheel and left rear wheel are yaw control wheels. Based on load Nzi of each wheel and their transfer amount ΔNzi which shifts to left rear and left front wheels in tire burst state, the distribution model of two yaw control wheels is established by modeling parameters including the steering angle θe of left front wheel, side slip angle and longitudinal ratio Si of left front wheel, longitudinal slip ratio Si of left rear and load Nzi of each wheel. The coordinated distribution of additional yaw moment Mu of two yaw control wheels of left front and left rear is realized. The steering of vehicle and the steering angle of left front wheel, and the slip rate Si of left front and left rear wheels are controlled simultaneously by the distribution of additional yaw moment Mu between left front wheel and left rear wheel. The combination of Mur and Mn can balance the tire burst yaw moment Mu′ produced by tire burst of right rear wheel. Insufficient or excessive steering of tire burst vehicle is compensated or eliminated produced by superposition effect of Mur and Mn. Fourth, the left rear wheel of right-turning vehicle. According to the vector model of Mu including Mn and Mur, the Mu achieves maximum value in the same direction of Mur and Mn, therefrom it can be determined that right rear wheel is the efficient yaw control wheel, and the right front wheel and right rear wheels are yaw control wheel. In tire burst control, the distribution model of two yaw control wheels is established by modeling parameters including steering angle θe of right front wheel, side slip angle and longitudinal slip ratio Si of right front wheel, longitudinal slip ratio Si of right rear and load Nzi of each wheel, based on the load Nzi of each wheel and their transfer amount ΔNzi which shifts to left rear and left front wheels in tire burst state. The steering angle θe of right front wheel and stable steering of the vehicle are controlled by distribution of additional yaw moment Mu between the two yaw control wheels; the slip rate Si of right front wheel and right rear wheel are controlled simultaneously. The combination control of Mur and Mn can balance tire burst yaw moment Mu′ produced by left rear tire burst. Insufficient or excessive steering of tire burst vehicle is compensated or eliminated by superposition effect of Mur and Mn. Similarly, the controlled wheel selection, control principle, rules and system of tire burst control of the left-turn vehicle are same as those of the right-turn vehicle.
(3). In duration from arriving of burst control entering signal ia to starting point of real burst time or/and the safety time of vehicle collision avoidance control, the braking A, C, B and D control may adopt the forms of B←A∪C or D←B∪A∪C logic combination and its logic cycle of period Hh. During real tire burst time, namely before or after time of the real tire burst point, braking force of tire burst wheel is relieved. When control combination of B←A∪C and it logic cycle are adopted, the control combination of A⊂C can be replaced by C control, that is, braking C control override A⊂C control. The differential braking control variable of brake C control for each wheel may adopt one of the parameter forms of {dot over (ω)}c, Sc, Qc. The target control value {dot over (ω)}ck, Sck or Qck of control variable {dot over (ω)}c, Sc or Qc are determined by the difference between target control value Qck1 {dot over (ω)}ck1 Sck1 of left wheel and the target control value of Qck2
{dot over (ω)}ck2 Sck2 of right wheel. According to the direction of the additional yaw moment Mu of tire burst, the wheel in which one of control variable {dot over (ω)}c, Sc or Qc of left wheel and right wheel of wheelset is assigned by smaller value is determined. The smaller values of the control variables in the left wheel and right wheel may are taken as zero. The distribution rules of {dot over (ω)}ck, Sck, Qck are expressed as: values of {dot over (ω)}ck, Sck, Qck are allocated to no-tire burst wheelset, and are allocated to no tire burst wheel in the tire burst wheelset. During each control period after real starting point of tire burst, the difference braking force of balanced brake B control of each wheel are decreased or are terminated with the increase of the differential braking force of C control for each wheelset, thus, tire burst brake control enters the logical cycle of braking C control or braking A∪C control.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/CN2018/000175 | May 2018 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/000100 | 5/10/2019 | WO | 00 |
