Patent Application
20190256104
This application is based on and claims the benefit of priority from earlier Japanese Patent Application No. 2018-27037 filed Feb. 19, 2018, the description of which is incorporated herein by reference.
The present disclosure relates to a technique for controlling driver assistance of a vehicle.
Japanese Unexamined Patent Application Publication No. 2016-68684 teaches a driver assistance control technology that assists people with driving a vehicle using the driving conditions of the vehicle and driving environment of the vehicle. When the behavior of the vehicle associated with the driver assistance control does not match the intention of the driver, the driver senses discomfort. Thus, for example, in the technique of adaptive cruise control, which is a mode of driver assistance, a technique of changing the degree of acceleration or deceleration depending on environment outside the vehicle has been proposed.
However, even when switching the modes of driver assistance, when a change in behavior of the vehicle is not smooth, a problem of giving the driver and others in the vehicle a sense of discomfort or anxiety arises. On the other hand, switching the modes of driver assistance is determined on the basis of the driving conditions of the vehicle and the driving environment of the vehicle, and prompt switching is desired.
It is, therefore, an object of this disclosure to provide a driver assistance control apparatus designed to keep a balance between suppressing behavior change of a vehicle and rapidly switching modes of driver assistance.
A first aspect provides a driver assistance control device of a vehicle. The driver assistance control device comprises: (a) an acquiring unit that acquires detected driving conditions of the vehicle and driving environment of the vehicle; and (b) a control unit that determines a mode of driver assistance depending on at least one of the acquired driving conditions and the driving environment and makes a driver assistance unit execute driver assistance in accordance with the determined mode of the driver assistance.
When the mode of the driver assistance is changed, the control unit reduces the change of the mode of the driver assistance for a predetermined first transition period.
According to the driver assistance control device of a vehicle according to the first aspect, it is possible to keep a balance between suppressing behavior change of the vehicle and rapidly switching the modes of the driver assistance.
A second aspect provides a driver assistance system. The driver assistance system according to the second aspect comprises the driver assistance control device according to the first aspect, a detection unit that detects driving conditions of the vehicle and a driving environment of the vehicle, and the driver assistance units.
According to the driver assistance system according to the second aspect, it is possible to keep a balance between suppressing behavior change of a vehicle and rapidly switching the mode of the driver assistance.
A third aspect provides a method for the driver assistance control of a vehicle. The method for the driver assistance control of a vehicle according to the third aspect comprises the steps of: acquiring the detected driving conditions of the vehicle and the driving environment of the vehicle; and determining the mode of the driver assistance depending on at least one of the acquired driving conditions and the driving environment. When the determined mode of the driver assistance is changed, the change of the mode of the driver assistance is reduced for a first transition period, and making the driver assistance unit execute the driver assistance in accordance with the determined mode of the driver assistance.
According to the method for setting control target vehicle according to the third aspect, it is possible to keep a balance between suppressing behavior change of a vehicle and rapidly switching the modes of the driver assistance. Further, the present disclosure can also be achieved as a program for the driver assistance control of a vehicle, or as a computer readable recording medium that stores the program.
The present invention will be understood more fully from the detailed description given hereinbelow and from the accompanying drawings of the preferred embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments but are for the purpose of explanation and understanding only.
The driver assistance control device, the driver assistance system, and the method for driver assistance control according to the present disclosure will be described below based on several embodiments.
As shown in
In the vehicle 500, the internal combustion engine ICE is provided with an output control device 31 for controlling the output of the internal combustion engine ICE. The output control device 31 comprises a throttle driving device that drives a throttle valve for controlling the output of the internal combustion engine ICE by adjusting the intake air amount, and a fuel injection driving device that drives a fuel injection device. Further, in the case where a diesel engine having a constant intake air amount is provided as an internal combustion engine ICE, the output is controlled by the fuel injection driving device. Furthermore, an electric motor may be used as a power source for driving in place of the internal combustion engine ICE, and in this case, an inverter and a converter can be used as the output control device 31. The output control device 31 is included in a driver assistance unit that executes driver assistance.
The braking device 502 is provided for each wheel 501. Each braking device 502 achieves braking of each wheel 501 using brake hydraulic pressure supplied via the braking line 503 in response to the operation of the driver's brake pedal. The brake line 503 comprises a brake piston that generates the brake hydraulic pressure in response to a brake pedal operation, and a brake fluid line. In the present embodiment, the braking assistance device 32 is provided in the braking line 503, and hydraulic pressure control is possible by an actuator such as an electric motor independently of the brake pedal operation, whereby braking assistance is achieved. Further, as for the braking line 503, a constitution may be adopted where a control signal line is used in place of the brake fluid line, and the actuator provided in each braking device 502 is operated. The braking assistance device 32 is provided in the driver assistance unit that executes driver assistance.
The steering wheel 504 is connected to the front wheel 501 via a steering device 44 having a steering rod and a steering mechanism. In the steering device 44, a steering assistance device 33 capable of driving the steering device 44 by an actuator, for example, an electric motor, is disposed. The steering assistance device 33 is capable of controlling driving of the steering device 44 independently of the operation of the steering wheel 504, thereby achieving steering assistance in accordance with the detection results obtained by the camera 221 and each millimeter wave radar 211. The steering assistance device 33 can also function as a steering force auxiliary device for assisting the steering force by the steering wheel 504 and easing the steering force. The steering assistance device 33 is provided in the driver assistance unit that executes driver assistance.
By the output control device 31 and the braking assistance device 32, a vehicle speed and inter-vehicle distance keeping control process, namely an adaptive cruise control (ACC) mode in which the system-equipped vehicle 500 is driven at a preset speed while keeping the inter-vehicle distance between the preceding vehicle and the system-equipped vehicle 500 at a constant value, is achieved as a driver assistance control mode. Moreover, by the braking assistance device 32 and the steering assistance device 33, an assistance process for keeping a driving lane that keeps the driving lane of the system-equipped vehicle 500, i.e., a lane keeping assist mode (also called a lane tracing assist mode) or a lane departure control mode (also called a lane departure alert mode) and assistance process for changing driving lanes that assists driving lane change of the system-equipped vehicle 500, namely lane change assist mode are achieved as driver assistance control modes. One or two of these driver assist modes are selected depending on the driving conditions of the vehicle 500 and the driving environment surrounding the vehicle 500 detected via the millimeter wave radar 211 and the camera 221 as detection units.
The lane keeping assist mode and the lane departure control mode may be executed separately from each other or alternatively the lane keeping assist mode may include the lane departure control mode.
As shown in
To the input/output interface 103, the radar ECU 21, camera ECU 22, yaw rate sensor 23, wheel speed sensor 24, rotation angle sensor 25, and the output control device 31, braking assistance device 32 and steering assistance device 33 are connected via control signal lines. Detection signals are received from the radar ECU 21, camera ECU 22, yaw rate sensor 23, wheel speed sensor 24, and rotation angle sensor 25; control signals dictating throttle valve opening and control signals dictating fuel injection amount are delivered to the output control device 31; control signals dictating braking level are delivered to the braking assistance device 32; and control signals dictating steering angle are delivered to the steering assistance device 33.
The millimeter wave radar 211 is a sensor that detects the distance, relative speed and angle of the target by emitting millimeter waves and receiving the waves reflected by the target. In the present embodiment, the millimeter wave radar 211 is disposed on each of the center and both sides of the front bumper 520 and both sides of the rear bumper 521. Unprocessed detection signals delivered from the millimeter wave radar 211 are processed in the radar ECU 21 and delivered to the driver assistance control device 100 as detection signals composed of a point or a sequence of points indicating one or more representative positions of the target. Alternatively, without the radar ECU 21 being provided, signals indicating unprocessed receiving waves may be delivered to the driver assistance control device 100 from the millimeter wave radar 211 as detection signals. When unprocessed receiving waves are used as detection signals, signal processing for identifying the position and distance of the target is executed in the driver assistance control device 100.
The camera 221 is a monocular imaging device having one imaging element such as a CCD, and is a sensor that delivers contour information of the target as image data that are detection results by receiving visible light. A feature point extraction process is performed on the image data delivered from the camera 221 in the camera ECU 22, and a pattern indicated by the extracted feature point and a comparative pattern indicating a contour of a target, namely a vehicle, that is to be set to a control target prepared in advance are compared with each other. When, the extracted pattern and the comparative pattern are identical or similar to each other, a frame image including the discriminated target is generated. On the other hand, when the extracted pattern and the comparative pattern are not identical or similar to each other, that is, when the two are dissimilar, the frame image is not generated. In the camera ECU 22, when more than one target is included in the image data, more than one frame image including each of the discriminated targets is generated, and these are delivered to the driver assistance control device 100 as detection signals. Each frame image is represented by pixel data, and includes position information of the discriminated target, that is, coordinate information. The number of frame images that can be included in the detection signals depends on the bandwidth between the camera ECU 22 and the driver assistance control device 100. Without separately providing the camera ECU 22, the unprocessed image data captured by the camera 221 may be delivered to the driver assistance control device 100 as the second detection signals. In this case, discrimination of the target using a contour pattern of the target may be executed in the driver assistance control device 100. In the present embodiment, the camera 221 is disposed at the upper center of the windshield 510. The pixel data delivered from the camera 221 are monochrome pixel data or color pixel data.
The yaw rate sensor 23 is a sensor for detecting the rotational angular velocity of the vehicle 500. The yaw rate sensor 23 is disposed, for example, in the central portion of the vehicle. The detection signals delivered from the yaw rate sensor 23 are voltage values proportional to the rotation direction and angular velocity.
The wheel speed sensor 24 is a sensor for detecting the rotation speed of the wheel 501, and is provided for each wheel 501. The detection signals delivered from the wheel speed sensor 24 are pulse waves indicating voltage values proportional to the wheel speed or intervals depending on the wheel speed. By using the detection signals from the wheel speed sensor 24, information on the vehicle speed, driving distance of the vehicle and the like can be obtained.
The rotation angle sensor 25 is a torque sensor for detecting the amount of torsion generated in the steering rod by steering the steering wheel 504, that is, the steering torque. In the present embodiment, the rotation angle sensor 25 is provided on the steering rod connecting the steering wheel 504 and the steering mechanism. The detection signals delivered from the rotation angle sensor 25 are voltage values proportional to the amount of twist.
The output control device 31 adjusts the opening of the throttle valve and the fuel injection amount in response to the operation of the accelerator pedal by the driver or irrespective of the driver's operation of the accelerator pedal, and is an actuator, for example, a stepping motor or a piezoelectric actuator, for controlling the output of the internal combustion engine ICE. A driver for controlling the operation of the actuator on the basis of the control signals from the CPU 101 is mounted on the output control device 31. In the present embodiment, the output control device 31 is provided in the intake manifold and the cylinder head, and controls the amount of air drawn into the internal combustion engine ICE and the amount of fuel injected into the cylinder of the internal combustion engine ICE in accordance with the control signals from the driver assistance control device 100.
The braking assistance device 32 is an actuator for achieving braking by the braking device 502 irrespective of the braking pedal operation by the driver. Further, a driver for controlling the operation of the actuator on the basis of the control signals from the CPU 101 is mounted on the braking assistance device 32. In the present embodiment, the braking assistance device 32 is provided in the braking line 503, and controls the hydraulic pressure in the braking line 503 in accordance with the control signals from the driver assistance control device 100. The braking assistance device 32 is constituted of a module provided with, for example, an electric motor and a hydraulic piston driven by the electric motor. Alternatively, a brake control actuator already introduced as an anti-skid device or an anti-lock braking system may be used.
With reference to
The CPU 101 acquires information on the driving conditions of the vehicle and the driving environment surrounding the vehicle (step S100). The information on driving conditions of the vehicle is information relating to the system-equipped vehicle 500, and the information on the driving environment surrounding the vehicle is information relating to objects other than the system-equipped vehicle 500 surrounding the system-equipped vehicle 500, namely targets. The driving conditions of the vehicle include the speed of the vehicle and the direction of the vehicle. The speed of the vehicle is acquired via the wheel speed sensor 24, and the direction of the vehicle is acquired via the yaw rate sensor 23 and the rotation angle sensor 25. The driving environment surrounding the vehicle includes information such as the position, speed and conditions of objects in the front, rear, left and right of the system-equipped vehicle 500. Examples of the objects include, for example, other vehicles, roads, road markings and road signs. The driving environment is acquired by the millimeter wave radars 211 and the camera 221.
The CPU 101 selects one of two of modes of the driver assistance using the acquired driving conditions and driving environment (step S110). The modes of the driver assistance include, for example, constant speed driving assistance process (i.e., the cruise control (CC) mode) that keeps the speed of the system-equipped vehicle 500 at a set speed, assistance process for keeping inter-vehicle distance and vehicle speed (i.e., the adaptive cruise control (ACC) mode) that keeps the inter-vehicle distance (i.e., follow distance) between the system-equipped vehicle 500 and a vehicle traveling ahead constant within the set speed, assistance process for preventing lane departure (i.e., the lane keeping assist (LKAS) mode that assists keeping the driving lane of the system-equipped vehicle 500, and assistance process for changing lanes (i.e., the lane change assist (LCA) mode) that assists changing the driving lane of the system-equipped vehicle 500 to another driving lane. For instance, the CPU 101 selects one of the CC mode and the ACC mode and one of the LKAS mode and the LCA mode. The ACC mode may alternatively include the CC mode. The CC mode and the ACC mode use a parameter (e.g., the speed of the system-equipped vehicle 500) in a direction in which the system-equipped vehicle 500 is heading, while the LKAS mode and the LCA mode use a parameter (e.g., the steered angle of the system-equipped vehicle 500) in a lateral direction of the system-equipped vehicle 500.
For example, when the driver turns on the ACC main switch disposed on the steering wheel while driving the system-equipped vehicle 500, and sets the speed of the vehicle, the assistance process for keeping inter-vehicle distance and vehicle speed (i.e., the ACC mode) is entered. As demonstrated in
As described above, the mode of the driver assistance is determined using the driving environment such as the position and speed of the other vehicle M1. Specifically, in a driving environment in which the millimeter wave radar 211 or the camera 221 can detect the other vehicle M1 in front, the CPU 101 selects the mode of the driver assistance to be the assistance process for keeping inter-vehicle distance and vehicle speed (i.e., the ACC mode). In a driving environment in which the millimeter wave radar 211 or the camera 221 cannot detect the other vehicle M1 in front, the mode of the driver assistance is determined to be assistance process for constant speed driving (i.e., the CC mode).
The assistance process for preventing lane departure and the assistance process for changing lanes will be described. For example, when the main switch of the LKAS disposed in the instrument panel is turned on, the assistance process for preventing lane departure can be executed. In the example of
As described above, the mode of the driver assistance is determined between, for example, the assistance process for preventing lane departure (e.g., the lane departure alert (LDA) mode) and the assistance process for changing lanes (e.g., the lane change assist (LCA) mode) using driving conditions such as operation of a direction indicator or a driving route of the vehicle M0. For instance, when there is an operation of a direction indicator, the mode of the driver assistance is determined to be the assistance process for changing lanes (i.e., LCA mode). Alternatively, when there is no operation of the direction indicator, the mode of the driver assistance is determined to be the assistance process for preventing lane departure (e.g., the lane departure alert (LDA) mode). In the example of
After the mode of the driver assistance is determined in step S100, the CPU 101 determines whether a request has been made to change or switch the mode of the driver assistance (step S120). Specifically, it is determined whether the mode of the driver assistance required to be entered in accordance with the driving conditions and the driving environment is different the mode of the driver assistance currently being executed. In the example of
If the mode of the driver assistance has been requested to be changed (step S120: Yes) meaning that one of the mode switches, as demonstrated in the table of
The first transition period is, for example, one second. The cutoff frequency of the low-pass filter can be set between 0.1 Hz and 1 Hz depending on the driving scene of the vehicle M0. For example, a cutoff frequency of 1 Hz is used under a driving scene of heavy traffic, and a cutoff frequency of 0.1 Hz is used under a driving scene of smooth traffic. In addition, considering slippery road conditions due to rain or snow, a lower cut-off frequency may be used in order to suppress change in control value. The first transition period and the cutoff frequency may be appropriately determined in accordance with the system such as the braking device 502 and the steering device 44 of the vehicle 500 or in accordance with the driving environment including the driving scene of the vehicle M0. For example, the weather information may be received via the mobile communication network or may be determined on the basis of operation of the windshield wiper. The condition of traffic congestion may be determined by receiving congestion information via a mobile communication network or radio, or by using the detected driving environment.
For instance, the main control value in the assistance process for preventing lane departure or the assistance process for changing lanes is the target steering angle delivered to the steering assistance device 33. In the assistance process for preventing lane departure, since the vehicle M0 has only to be kept at the center of a lane, the amount of change and change rate of the target steering angle are small. On the other hand, in the assistance process for changing lanes, since the vehicle M0 is transferred from the current lane LN1 to lane LN2 after lane change, the amount of change and change rate of the target steering angle are large compared with those of the assistance process for preventing lane departure. Therefore, the change of the mode of the driver assistance between the assistance process for preventing lane departure and the assistance process for changing lanes, in particular, the change of the mode of the driver assistance from the assistance process for preventing lane departure to the assistance process for changing lanes is likely to provoke discomfort and anxiety to those in the vehicle M0 (i.e., the vehicle 500).
The main control values in the assistance process for keeping inter-vehicle distance and vehicle speed and the assistance process for constant speed driving are the demand output value delivered to the output control device 31 and the braking command value delivered to the braking assistance device 32. The demand output value includes the fuel injection amount, the intake air amount, and the ignition timing. The braking command value includes the brake hydraulic pressure value applied to the braking line 503, that is, the operation amount of the hydraulic piston. In the assistance process for keeping inter-vehicle distance and vehicle speed, in order to keep a predetermined inter-vehicle distance, the speed of the vehicle M0 is changed in response to the speed of the other vehicle M1. That is, the target speed changes. On the other hand, in the assistance process for constant speed driving, since the speed set by the driver is kept constant, the target speed of the vehicle M0 does not change. Therefore, the change of the mode of the driver assistance between the assistance process for keeping inter-vehicle distance and vehicle speed and the assistance process for constant speed driving involves change of vehicle speed and is likely to provoke discomfort and anxiety to those in the vehicle 500. Typically, when the speed of the vehicle M0 is lower than the speed set by the driver in the execution of the assistance process for keeping inter-vehicle distance and vehicle speed, if the mode of the driver assistance is switched to the assistance process for constant speed driving, acceleration is executed with the set speed as the target speed. On the other hand, when the mode of the driver assistance is switched from the assistance process for constant speed driving to the assistance process for keeping inter-vehicle distance and vehicle speed, the target speed becomes the speed of the other vehicle M1 in front and deceleration is executed.
In any of the cases mentioned above, change of the control value associated with the change of the mode of the driver assistance is determined by the driving conditions and the driving environment, and is independent of the direct operation amount by the driver. Therefore, the change of the control value very often becomes different from the sense of the driver, and is likely to provoke discomfort and anxiety on the part of the driver and other occupants. According to the driver assistance control device 100 according to the present embodiment, change of the mode of the driver assistance is eased during the transition period, that is, change of value from the control value to execute the driver assistance before the change to the control value to execute the driver assistance after the change is suppressed, or change to the target value in accordance with the mode of the driver assistance after the change is suppressed. Therefore, change of vehicle behavior associated with the change of the mode of the driver assistance is suppressed.
With reference to
Further, the application of the low pass filter to the control value includes both the application to the control value for executing driver assistance determined using the driving conditions and the driving environment as shown in
Returning to
According to the driver assistance control apparatus 100 according to the first embodiment described above, when the mode of the driver assistance is requested to be changed, the change of the mode of the driver assistance, that is, change of the target control value associated with the change of the mode of the is reduced for the first transition period. Therefore, fluctuation and change in vehicle behavior associated with change in the mode of the driver assistance are suppressed, and the sense of anxiety and discomfort of the occupants including the driver can be reduced or eliminated.
According to the driver assistance control device 100 according to the first embodiment, reduction in change of the target control value used in the mode of the driver assistance is canceled after the lapse of the first transition period. After the lapse of the first transition period, it is possible to execute the driver assistance promptly reflecting the driving conditions and the driving environment using the control value in accordance with the determined, for example, the control value where a low-pass filter is not applied. That is, according to the driver assistance control apparatus 100 according to the first embodiment, the target control value is not reduced at all times. Therefore, for example, there only exists a cutoff frequency when the low pass filter is applied at all times, and a degree of freedom for adjusting the degree of reduction by a coefficient when an averaging coefficient is applied at all times. Therefore, it is not easy to fulfill both the prompt execution of the driver assistance after change and the suppression of the change of vehicle behavior associated with the change of the mode of the driver assistance. On the other hand, according to the driver assistance control apparatus 100 according to the first embodiment, it is possible to fulfill both the reduction or elimination of the sense of anxiety and discomfort of the occupants including the driver caused by the change of vehicle behavior associated with a large change in the control value that is likely to develop at the time of changing the mode of the driver assistance, and prompt switching to and execution of driver assistance in response to the driving conditions and the driving environment.
According to the driver assistance control apparatus 100 according to the first embodiment, when the mode of the driver assistance is not changed, the low pass filter is not applied to the control value. Therefore, it is possible to achieve prompt driver assistance in response to the driving conditions and the driving environment in the mode of the driver assistance in execution. For example, at the time of executing the assistance process for keeping inter-vehicle distance and vehicle speed, it is possible to improve the followability to speed change of the other vehicle M1 in front as compared with the case where the low pass filter is applied. At the time of executing the assistance process for preventing lane departure, it is possible to improve the followability of keeping the center of a lane as compared with the case where the low pass filter is applied.
The present disclosure has been described above on the basis of embodiments and modifications, but the embodiments of the invention described above are for facilitating the understanding of the present disclosure and do not limit the present disclosure. The present disclosure can be modified and improved without departing from the drift and the scope of the claims, and the present disclosure includes equivalents thereof. For example, technical features in the embodiments and the modifications, corresponding to the technical features in each embodiment described in the section of Summary of the invention can be adequately replaced or combined in order to solve part or all of the problems mentioned above, or in order to achieve some or all of the effects mentioned above. Further, unless the technical features are described as essential in the present specification, they can be deleted as appropriate. For example, setting the driver assistance control device of a vehicle according to the first mode mentioned above as application example 1.
As apparent from the above discussion, the driver assistance control device for use in a vehicle comprises: (a) an acquiring unit (i.e., the input/output interface 103) that acquires given driving conditions of a vehicle and driving environment of the vehicle; and (b) a control unit (i.e., the CPU 101) which selectively performs one of modes of driver assistance including a first driver assistance mode (e.g., the adaptive cruise control (ACC) mode or the lane keeping assist mode (LKAS) mode) and a second driver assistance mode (e.g., the cruise control (CC) mode or the lane change assist (LCA) mode).
The control unit calculates a first target value of a given parameter associated with the driving conditions or the driving environment and achieves the first driver assistance mode using the first target value.
The control unit also calculates a second target value of the same parameter as that used in the first driver assistance mode and achieves the second driver assistance mode using the second target value.
The control unit determines whether the mode of the driver assistance has been requested to be changed from the first driver assistance mode to the second driver assistance mode or not. When such as request is determined to have been made, the control unit calculates a rate of change from the first target value to the second target value and then decreases the rate of change. The control unit initiates the second driver assistance mode and then changes the given parameter from the first target value to the second target value at the decreased rate of change for a given transition period.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-027037 | Feb 2018 | JP | national |
