Patent Application
20200293004
The present disclosure relates to a control system having variable rate damping control. More particularly, the present disclosure relates to a control system for a machine, where the control system variably damps movement of the machine as a function of a magnitude of an operator command.
Some machines or mechanical apparatuses are equipped with control systems requiring human input to manage operation of moving components. For example, a trajectory of a vehicle is managed by operation of a variety of control input devices, which are referred to as inceptors, that are manipulated by a human operator. The inceptors may be actively driven to provide force based tactile cues to the human operator and provide backdrive capability, and may be referred to as active inceptors. Backdriving an inceptor provides a machine operator with an indication as to what the control system is doing to the machine and provides control inputs to maintain a particular machine state. In one example, inceptor that is backdriven assist a helicopter pilot in maintaining a particular course and/or heading. In another example, an inceptor that is backdriven assists the driver of a vehicle with maintaining a stable velocity while driving down-hill.
It is to be appreciated that when an operator utilizes an inceptor that is backdriven, the backdriven inceptor may inadvertently come into contact with the operator's limb. This unintentional contact by the operator's limb with the inceptor that is backdriven is received as input by the control system. Moreover, the unintentional contact by the operator may be amplified by the control system.
In several aspects of the present disclosure, a control system for a machine having variable rate damping based control (VRDC) is disclosed. The machine includes one or more active inceptors and one or more inline actuators. The control system includes one or more processors and a memory coupled to the one or more processors. The memory stores data comprising a database and program code that, when executed by the one or more processors, causes the control system to receive an inceptor position from one or more active inceptors. The control system is also caused to calculate an operator command based on at least the inceptor position. The control system is further caused to determine an amplitude of the operator command, where the amplitude is a magnitude of the operator command. The control system is caused to determine a variable gain based on the amplitude of the operator command. The control system further is caused to determines an actuation command based on the variable gain. A total actuator position is a sum of the actuation command and the inceptor position. The control system is caused to send the actuation command to the one or more inline actuators. The one or more inline actuators actuate into the total actuator position to variably damp movement of the machine. The machine is variably damped as a function of the magnitude of the operator command.
In another aspect, a method for variably damping a machine by a control system having VRDC is disclosed. The method includes receiving, by a control module, an inceptor position from one or more active inceptors of the machine. The method includes calculating, by the control module, an operator command based on at least the inceptor position. The method also includes determining an amplitude of the operator command, wherein the amplitude is a magnitude of the operator command. The method further includes determining a variable gain based on the amplitude of the operator command. The method also includes determining an actuation command based on the variable gain. A total actuator position is a sum of the actuation command and the inceptor position. The method further includes sending the actuation command to the one or more inline actuators. The method also includes actuating the one more inline actuators into the total actuator position to variably damp movement of the machine. The machine is variably damped as a function of the magnitude of the operator command.
The features, functions, and advantages that have been discussed may be achieved independently in various embodiments or may be combined in other embodiments further details of which can be seen with reference to the following description and drawings.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The present disclosure is directed towards a control system having variable rate damping based control (VRDC). The control system is configured to variably damp movement of a machine, where the machine is variably damped as a function of a magnitude of an operator command. The operator command is received as input by the control system. In some instances, the movement of the machine is created by an inadvertent operator command. However, it is to be appreciated that the disclosed control system does not determine if an operator command is created inadvertently by an individual. The machine includes one or more inline actuators and one or more active inceptors. The control system instructs the one or more inline actuators of the machine to actuate into a total actuator position to variably damp the movement of the machine. The total actuator position of the one or more inline actuators is determined in part by a variable gain applied to a rate error signal as well as an inceptor position of the active inceptors.
The disclosure also describes a variable gain schedule for selecting the value of the variable gain. The variable gain schedule includes an inversely proportional relationship between the magnitude of the operator command received by the control system and the variable gain. Accordingly, small-amplitude operator commands result in a maximum gain value being selected. The value of the variable gain decreases as the amplitude of the operator command increases. Furthermore, a minimum gain value is selected in response to receiving relatively large-amplitude operator commands. Therefore, the machine rejects relatively small-amplitude operator commands, which are likely to be created inadvertently, and becomes more responsive as the amplitude of the operator commands increase.
Turning now to
Although a helicopter 12 is illustrated, it is to be appreciated that
The helicopter 12 of
The control effector devices 18 of the helicopter 12 of
In each of the foregoing machine 10 examples, the control effector devices 18 are controlled by a control module 20 operably connected to the operator interface 22 disposed within a cabin 38 of the machine 10. The operator interface 22 includes one or more active inceptors 14 operably connected to the control effector devices 18 of the machine 10. The active inceptors 14 of the helicopter 12 of
The collective 42 is an active inceptor 14 that changes an angle of attack of the main rotor blades 26 via the swashplate 46. Altering the angle of attack of the main rotor blades 26 increases or decreases a pitch angle of all of the main rotor blades 26 equally, thereby causing the helicopter 12 to ascend or descend accordingly. Furthermore, altering the angle of attack of the main rotor blades 26 increases or decreases torque, thereby translating into thrust and lift for the helicopter 12. In one embodiment, throttle controls managing the engine 30 of the helicopter 12 are interlinked with the collective 42. In forward and/or rearward flight, the collective 42 operates to adjust power through the main rotor 24 via a main rotor blade 26 pitch setting, while in hovering flight, the collective 42 adjusts helicopter 12 height and/or vertical speed.
The anti-torque pedals 44 of the helicopter 12 are active inceptors 14 that control collective pitch supplied to the tail rotor 28. Thus, the anti-torque pedals 44 have the primary effect of managing a yaw or rotational rate of the helicopter 12. In forward and/or rearward flight, the anti-torque pedals 44 adjust a sideslip angle of the helicopter 12, and in hovering flight, the anti-torque pedals 44 control a yaw rate and heading direction for the helicopter 12.
One or more of the active inceptors 14 of the operator interface 22 is actively backdriven. An active inceptor 14 is configured to provide tactile cues to the pilot or operator of the helicopter 12 and also provides backdrive functionality. To provide the active backdrive functionality and tactile cues for the pilot, active inceptors 14 are equipped with a backdrive actuator 50. A key tactile cue provided by the backdrive actuator 50 is a zero-force detent 51. The backdrive actuator 50 manipulates or moves the position of the zero-force detent 51 on the active inceptors 14 that reflects an inceptor position required to maintain a current machine state 33. The backdrive actuator 50 backdrives each active inceptor 14 through the zero-force detent 51. For example, the cyclic 40 of the helicopter 12 is positioned at the zero-force detent 51 to maintain a given flight course or heading. However, an operator may exert a breakout force upon the cyclic 40 to change the current flight course or heading of the helicopter 12. Specifically, the cyclic 40 is urged or moved out of the zero-force detent 51 when the breakout force is applied.
As an example, during an automated flight of a helicopter 12 of the present disclosure, the cyclic 40, collective 42, and anti-torque pedals 44 may be actively moved and adjusted by an onboard flight system to maintain a particular main rotor 24 and tail rotor 28 positioning, trims, and power levels. Accordingly, the helicopter 12 follows a flight course or heading without operator or pilot force input. In order to counteract torque imparted to a fuselage 52 of the helicopter 12 by the main rotor 24, the onboard flight system may command the anti-torque pedals 44 to move to a position commensurate with the desired flight course or heading, and to maintain the desired flight course or heading by constantly adjusting the position of the anti-torque pedals 44. Accordingly, the anti-torque pedals 44, as well as the collective 42, and the cyclic 40 may be actively backdriven via the zero-force detent 51 as the onboard flight system operates continuously to maintain a given flight course or heading. The zero-force detent 51 represents the required position of the active inceptors 14 to maintain the desired flight course or heading. The zero-force detent 51 alleviates series actuator saturation, gives the pilot or operator an indication of what the helicopter 12 is doing at a given point in time, and allows the pilot to make off-axes control inputs necessary to maintain a current machine state 33, such as a heading when control inputs are made in other axes. Moreover, the zero-force detent 51 offers the pilot an indication of where the vehicular trim is at a given point in time and showing how much control authority remains over the various active inceptors 14 which are equipped to the helicopter 12.
Turning now to
In
The control module 20 executes instructions to receive the inceptor position 72 from the active inceptor 14. Specifically, the control module 20 executes instructions to receive the inceptor position 72 from the position sensor 66 and the operator input force from the force sensor 70. Additional instructions to receive current machine states 33 such as vehicle dynamics, gyroscopic position, velocity, altitude, bank angle, and the like from a plurality of vehicle sensors 74 are also received by the control module 20. In several aspects, the plurality of vehicle sensors 74 are used by the control module 20 to manage operations of the machine 10, helicopter 12, or the like. In an example, the vehicle sensors 74 are used by the control module 20 to determine and manage vehicle dynamics 76, such as flight trajectory, path, or other such movement.
The control module 20 sends a first command 78 to the active inceptor 14. The first command 78 includes a force feel profile 79 component of the first command 78 including the zero-force detent 51 and a detent force gradient 80.
In one embodiment, the operator control input 62 is either an automatic input from the control module 20 (i.e., a zero-force detent command detent as seen in
Referring to
Referring now to
The control module 20 (
The first subfunction 122 of the piecewise controller gain 120 is applied to operator commands δOP ranging in value from zero to a first magnitude value |u1|. The second subfunction 124 of the piecewise controller gain 120 is applied to operator commands δOP ranging in value from the first magnitude value |u1| to a second magnitude value |u2|. The third subfunction 126 is applied to operator commands δOP ranging in value from the second magnitude value |u2| to a maximum control limit of the magnitude |u| of the operator command δOP. The maximum control limit may be an infinite value. The variable gain 88 ranges in value between a maximum value Kr
It is to be appreciated that the specific values of the maximum value Kr
The first subfunction 122 is equal to the maximum value Kr
The gain schedule 90 also defines a midpoint |umidpoint|, which is located at a midpoint between the first magnitude value |u1| and the second magnitude value |u2|. Magnitude values ranging from zero to about the midpoint |umidpoint| represent small-amplitude operator command δOP, while magnitude values ranging from the about the midpoint |umidpoint| to the maximum control input represent large-amplitude operator commands δOP. Thus, the first magnitude value |u1| is a small-amplitude operator command δOP and the second magnitude value |u2| is a large-amplitude operator command δOP. It is to be appreciated that small-amplitude operator commands δOP tend to be created by inadvertent operator input, while large-amplitude operator commands δOP are more likely to be generated intentionally. However, it is to be appreciated that not all small-amplitude operator commands δOP are inadvertent. Furthermore, it is to be understood the control system 54 is not configured to determine if the operator command δOP is inadvertent. Instead, the control system 54 simply applies a relatively high variable gain 88 in response to receiving small-amplitude operator commands δOP.
As the magnitude |u| of the operator command δOP increases, the likelihood that the operator command δOP is inadvertent or unintentional decreases. Accordingly, as the magnitude |u| of the operator command δOP increases within Interval II, the value of the variable gain 88 decreases. The inversely proportional relationship between the amplitude 93 of the operator command δOP and the variable gain 88 of the second subfunction 124 is based on the control system's 54 sensitivity to changes in magnitude of the operator command δOP. That is, if the control system 54 is highly sensitive to changes in the magnitude |u| of the operator command δOP, then the slope of the second subfunction 124 increases. Specifically, it is to be appreciated that the equation of a line is expressed as y=mx+b, where the variable m represents slope. Therefore, as the slope m increases (i.e., becomes steeper), then the sensitivity of the control system 54 to changes in magnitude of the operator command δOP, increases. Similarly, when the slope m decreases, then the sensitivity of the control system 54 to changes in magnitude |u| of the operator command δOP decreases as well. The inversely proportional relationship of the second subfunction 124 includes a negative slope (i.e., y=−mx+b).
Referring back to
The control module 20 monitors the machine 10 to determine the measured rate 104. Accordingly, the measured rate 104 represents an actual state of the machine 10. For example, if the machine 10 is the helicopter 12 (seen in
Continuing to refer to
An acceleration command component {dot over (r)}c is derived based on the variable gain 88 and the rate error rerr. In one aspect, the acceleration command component {dot over (r)}c is the product of the variable gain 88 and the rate error rerr (i.e., variable gain 88×the rate error rerr). It is to be appreciated the acceleration command component {dot over (r)}c may be applied to a variety of acceleration commands such as, but not limited to, yaw, pitch, roll, or vertical rate commands. The acceleration command component {dot over (r)}c and one or more off-axis inputs 96 are received as input by a mixing block 112 and are mixed together. An unlimited actuator command Cactuator is generated based on mixing the one or more off-axis inputs 96 and the acceleration command component {dot over (r)}c together.
A control authority limit 108 is then applied to the unlimited actuator command Cactuator. A stability augmentation system command δSAS is determined based on applying the control authority limit 108 to the unlimited actuator command Cactuator. The stability augmentation system command δSAS is applied in combination with the inceptor position 72 to the one or more inline actuators 32. The total actuator position δTOT is a sum of the stability augmentation system command δSAS and the inceptor position (72). In response to receiving the stability augmentation system command δSAS in combination with the inceptor position 72, the one or more inline actuators 32 move into the total actuator position δTOT. When the one or more inline actuators 32 move into the total actuator position δTOT, movement of the machine 10 (
Referring to both
It is to be appreciated that fly-by-wire systems send an electronic signal indicating the inceptor position 72 electronically to the one or more inline actuators 32. In other words, the control module 20 electronic signal sent to the one or more inline actuators 32 indicates the inceptor position 72 as well as the stability augmentation system command δSAS component. However, in a partial authority control system 54, the inceptor position 72 is sent as a mechanical signal to the one or more inline actuators 32. That is, when a partial authority system is employed the control module 20 electronic signal sent to the one or more inline actuators 32 only includes the stability augmentation system command δSAS, and not the inceptor position 72 component.
Referring to
The backdrive rate of an active inceptor 14 indirectly affects the value of the variable gain 88. Specifically, when the backdrive rate of a given active inceptor 14 is relatively high, this indicates there is a relatively high chance that relative movement between the active inceptor 14 and the zero-force detent 51 was created unintentionally by the operator. Such relative movement between the active inceptor 14 and the zero-force detent may be referred to as an inadvertent operator input and is usually a small-amplitude input. As seen in
In block 204, the control module 20 calculates the operator command δOP based on the inceptor position 72 received from the one or more active inceptors 14. Specifically, the operator command δOP is determined based on the difference between the zero-force detent command δdetent and the inceptor position 72. The method 200 may then proceed to block 206.
In block 206, the control module 20 determines the amplitude 93 of the operator command δOP, where the amplitude is the magnitude |u| of the operator command δOP. The method 200 may then proceed to block 208.
In block 208, the control module 20 determines the variable gain 88. Specifically, as seen by the variable gain schedule 90 in
In block 210, the control module 20 determines an actuation command that is sent to the one or more inline actuators 32, where the actuation command is based on the variable gain 88. As seen in
In block 212, in response to receiving the actuation command and the inceptor position 72, the one or more inline actuators 32 move into the total actuator position δTOT to variably damp movement of the machine 10. As mentioned above, the machine 10 is variably damped as a function of the magnitude |u| of the operator command δOP. The method 200 may then terminate.
Referring generally to the figures, the disclosed control system 54 provides various technical effects and benefits. Specifically, the control system 54 employs a stability augmentation system (SAS) based approach for providing dynamic stability and control augmentation while improving control response. Conventional SAS based control systems do not account for the amplitude of the operator input when determining the damping rate, and therefore tend to have sluggish control responses. In contrast, the present disclosure describes an approach for improving the control response of an SAS based control system by varying the gain based on the magnitude of the operator input. Specifically, the control system 54 applies a maximum variable gain value in response to small-amplitude operator inputs, which in turn result in a more damped machine. Thus, the machine tends to reject relatively small-amplitude operator control inputs. As mentioned above, small-amplitude operator control inputs are likely to be created by inadvertent operator control input.
It is to be appreciated that the likelihood that an operator control input is inadvertent decreases as the amplitude of the operator command increases. That is, in other words, large-amplitude operator control inputs tend to be intentional. Accordingly, the value of the variable gain decreases as the amplitude of the operator control input increases based on an inversely proportional relationship between operator command input and the variable gain. Thus, the control system 54 applies a minimum value for the variable gain in response to large-amplitude operator commands, which are more likely to be intentional. Thus, the minimum gain results a less damped machine response. In other words, the minimum gain results in a machine that is more responsive intentional operator inputs.
Turning now to
The processor 84 includes one or more devices selected from microprocessors, micro-controllers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits, or any other devices that manipulate signals (analog or digital) based on operational instructions that are stored in the memory 82. Memory 82 includes a single memory device or a plurality of memory devices including, but not limited to, read-only memory (ROM), random access memory (RAM), volatile memory, non-volatile memory, static random-access memory (SRAM), dynamic random-access memory (DRAM), flash memory, cache memory, or any other device capable of storing information. The mass storage memory device 136 includes data storage devices such as a hard drive, optical drive, tape drive, volatile or non-volatile solid-state device, or any other device capable of storing information.
The processor 84 operates under the control of an operating system 1046 that resides in memory 82. The operating system 1046 manages computer resources so that computer program code embodied as one or more computer software applications, such as an application 1048 residing in memory 82, may have instructions executed by the processor 84. In an alternative example, the processor 84 may execute the application 1048 directly, in which case the operating system 1046 may be omitted. One or more data structures 1049 also reside in memory 82, and may be used by the processor 84, operating system 1046, or application 1048 to store or manipulate data.
The I/O interface 86 provides a machine interface that operatively couples the processor 84 to other devices and systems, such as the network 1026 or external resource 1042. The application 1048 thereby works cooperatively with the network 1026 or external resource 1042 by communicating via the I/O interface 86 to provide the various features, functions, applications, processes, or modules comprising exemplary embodiments. The application 1048 also includes program code that is executed by one or more external resources 1042, or otherwise rely on functions or signals provided by other system or network components external to the control module 20. Indeed, given the nearly endless hardware and software configurations possible, persons having ordinary skill in the art will understand that embodiments may include applications that are located externally to the control module 20, distributed among multiple computers or other external resources 1042, or provided by computing resources (hardware and software) that are provided as a service over the network 1026, such as a cloud computing service.
The HMI 1040 is operatively coupled to the processor 84 of control module 20 in a known manner to allow a user to interact directly with the control module 20. The HMI 1040 may include video or alphanumeric displays, a touch screen, a speaker, and any other suitable audio and visual indicators capable of providing data to the user. The HMI 1040 also includes input devices and controls such as an alphanumeric keyboard, a pointing device, keypads, pushbuttons, control knobs, microphones, etc., capable of accepting commands or input from the user and transmitting the entered input to the processor 84.
A database 1044 may reside on the mass storage memory device 1036 and may be used to collect and organize data used by the various systems and modules described herein. The database 1044 may include data and supporting data structures that store and organize the data. In particular, the database 1044 may be arranged with any database organization or structure including, but not limited to, a relational database, a hierarchical database, a network database, or combinations thereof. A database management system in the form of a computer software application executing as instructions on the processor 84 may be used to access the information or data stored in records of the database 1044 in response to a query, where a query may be dynamically determined and executed by the operating system 1046, other applications 1048, or one or more modules.
The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.
