Trajectory tracking method and device based on steer-by-wire fault tolerance, equipment and medium

Abstract

The invention provides a trajectory tracking method, device and equipment based on steer-by-wire fault tolerance and a medium wherein the trajectory tracking method based on steer-by-wire fault tolerance comprises: when a steering execution motor has a fault, determining expected control parameters for vehicle trajectory tracking, the expected control parameters comprising an expected steering wheel steering angle and an expected differential yaw moment; reducing the expected steering angle of the steering wheel and increasing the expected differential yawing moment; determining a front axle differential steering torque and an output torque of a steering execution motor based on the expected steering wheel steering angle; and trajectory tracking is carried out based on the front axle differential steering torque, the expected differential yawing torque and the output torque of the steering execution motor. When the steering-by-wire system breaks down, the front axle differential steering torque can be used for assisting the fault steering-by-wire system in stably tracking the expected steering wheel steering angle, and then the requirement of vehicle trajectory tracking for steering is met. Meanwhile, the stability of vehicle trajectory tracking can be improved.

Description

Technical Field

[0001] The present application relates to the field of vehicle steering control, and more specifically, to a trajectory tracking method, apparatus, device, and medium based on steer-by-wire fault tolerance. Background Art

[0002] Steer-by-wire technology decouples the steering wheel from the steering wheel, facilitating the implementation of autonomous driving. By eliminating numerous steering transmission mechanisms, steer-by-wire systems offer the advantages of accurate and rapid response. Furthermore, vehicle electrification is driving the development of distributed drive vehicles. The combination of steer-by-wire and drive-by-wire systems transforms the entire vehicle into a typical overdrive system. By enabling mutual compensation between the drive system's actuators, the system's fault tolerance can be significantly improved.

[0003] However, existing research on using differential yaw torque to track and control vehicle trajectory has not considered the impact of differential steering; and in existing research on differential steering, the focus is mainly on traditional vehicles rather than intelligent driving vehicles, that is, the focus is mainly on differential power steering. The few articles that study differential steering do not fully utilize the differential yaw torque generated during differential steering, and even regard it as a negative effect that affects vehicle stability. Summary of the Invention

[0004] The present invention aims to provide a steer-by-wire fault-tolerant trajectory tracking method, apparatus, electronic device, and storage medium. These methods utilize the front axle differential steering torque to assist the faulty steer-by-wire system in smoothly tracking the desired steering wheel angle when the steer-by-wire system fails, thereby achieving the steering requirements of vehicle trajectory tracking. Furthermore, these methods are used to improve the stability of vehicle trajectory tracking.

[0005] In a first aspect, the present invention provides a trajectory tracking method based on steer-by-wire fault tolerance, the method comprising:

[0006] When the steering actuator motor fails, determining desired control parameters for vehicle trajectory tracking, the desired control parameters including a desired steering wheel angle and a desired differential yaw moment;

[0007] reducing the desired steering wheel angle and increasing the desired differential yaw moment;

[0008] determining a front axle differential steering torque and an output torque of the steering actuator motor based on the desired steering wheel angle;

[0009] Trajectory tracking is performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

[0010] The method of the first aspect of the present application can determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the method can determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Furthermore, trajectory tracking can be performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the failed steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, the desired steering wheel angle can be reduced and the desired differential yaw torque increased, thereby reducing the requirement for the steering wheel angle. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0011] In an optional embodiment, the performing trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor includes:

[0012] determining an output torque of the front axle wheel hub motor and an output torque of the rear axle wheel hub motor based on the front axle differential steering torque and the desired differential yaw torque;

[0013] Trajectory tracking is performed based on the output torque of the steering actuator motor, the output torque of the front axle hub motor, and the output torque of the rear axle hub motor.

[0014] This optional implementation can determine the output torque of the front axle hub motor and the output torque of the rear axle hub motor based on the front axle differential steering torque and the desired differential yaw torque, and then can perform trajectory tracking based on the output torque of the steering execution motor, the output torque of the front axle hub motor and the output torque of the rear axle hub motor.

[0015] In an optional embodiment, reducing the desired steering wheel angle and increasing the desired differential yaw moment includes:

[0016] determining a fault degree of the steering actuator motor;

[0017] determining a weight coefficient of the desired steering wheel angle and a weight coefficient of the desired differential yaw moment based on the degree of failure of the steering actuator motor, wherein the weight coefficient of the desired steering wheel angle increases as the degree of failure of the steering actuator motor increases;

[0018] The desired steering wheel angle is reduced and the desired differential yaw moment is increased based on a weight coefficient of the desired steering wheel angle and a weight coefficient of the desired differential yaw moment.

[0019] This optional embodiment determines the degree of failure of the steering actuator motor, and then determines the weight coefficient of the expected steering wheel angle and the weight coefficient of the expected differential yaw torque based on the degree of failure of the steering actuator motor, wherein the weight coefficient of the expected steering wheel angle increases with the increase in the degree of failure of the steering actuator motor, thereby being able to reduce the expected steering wheel angle and increase the expected differential yaw torque based on the weight coefficient of the expected steering wheel angle and the weight coefficient of the expected differential yaw torque.

[0020] In an optional implementation manner, determining the fault degree of the steering actuator motor includes:

[0021] Acquiring a torque sensor detection signal of the steering actuator motor;

[0022] determining the efficiency of the steering actuator motor based on a detection signal of a torque sensor of the steering actuator motor;

[0023] A degree of failure of the steering actuating motor is determined based on the effectiveness of the steering actuating motor.

[0024] This optional implementation method obtains the torque sensor detection signal of the steering actuator motor, and then can determine the efficiency of the steering actuator motor based on the torque sensor detection signal of the steering actuator motor, thereby determining the degree of failure of the steering actuator motor based on the efficiency of the steering actuator motor.

[0025] In an optional embodiment, determining the front axle differential steering torque based on the expected steering wheel angle includes:

[0026] When the steering actuator motor is in a complete failure, the front axle differential steering torque is determined based on the desired steering wheel angle.

[0027] This optional implementation can utilize all the desired steering wheel angles to determine the front axle differential steering torque when the steering actuator motor is in complete failure, thereby allowing the front axle differential steering torque to meet all steering requirements.

[0028] In an optional embodiment, determining the desired control parameters for vehicle trajectory tracking includes:

[0029] Acquiring vehicle parameters, wherein the vehicle parameters include vehicle position error and vehicle heading angle error;

[0030] The desired control parameter is determined based on the vehicle position error and the vehicle heading angle error.

[0031] This optional implementation can obtain vehicle parameters, wherein the vehicle parameters include a vehicle position error and a vehicle heading angle error, and then the desired control parameters can be determined based on the vehicle position error and the vehicle heading angle error.

[0032] In an optional embodiment, determining the desired control parameter based on the vehicle position error and the vehicle heading angle error includes:

[0033] Get boundary conditions;

[0034] The desired control parameter is determined based on the vehicle position error, the vehicle heading angle error, and the boundary conditions.

[0035] This optional implementation can obtain boundary conditions, and further can determine the desired control parameters based on the vehicle position error, the vehicle heading angle error, and the boundary conditions.

[0036] In a second aspect, the present invention provides a trajectory tracking device based on steer-by-wire fault tolerance, the device comprising:

[0037] a first determining module, configured to determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails, the desired control parameters including a desired steering wheel angle and a desired differential yaw moment;

[0038] an adjusting module, configured to reduce the desired steering wheel angle and increase the desired differential yaw moment;

[0039] a second determining module, configured to determine a front axle differential steering torque and an output torque of the steering execution motor based on the desired steering wheel angle;

[0040] A control module is configured to perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

[0041] The second aspect of the present application is capable of determining desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the apparatus can determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Furthermore, trajectory tracking can be performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the failed steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, the apparatus can reduce the desired steering wheel angle and increase the desired differential yaw torque before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, thereby reducing the steering wheel angle requirement. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0042] In a third aspect, the present invention provides an electronic device, comprising:

[0043] processor; and

[0044] A memory is configured to store machine-readable instructions, which, when executed by the processor, execute the trajectory tracking method based on wire-controlled steering fault tolerance as described in any of the aforementioned embodiments.

[0045] The electronic device of the third aspect of the present application, by executing a trajectory tracking method based on steer-by-wire fault tolerance, can determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the electronic device can determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Furthermore, the electronic device can perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when the steer-by-wire system fails, the front axle differential steering torque is used to assist the failed steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, the electronic device can reduce the desired steering wheel angle and increase the desired differential yaw torque before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, thereby reducing the steering wheel angle requirement. This reduces the need for the front axle to output an excessively high drive torque to achieve a larger differential steering torque, thereby preventing the excessive drive torque from affecting vehicle tracking stability.

[0046] In a fourth aspect, the present invention provides a storage medium storing a determination machine program, wherein the determination machine program is executed by a processor as the trajectory tracking method based on wire-controlled steering fault tolerance as described in any of the aforementioned embodiments.

[0047] The storage medium of the fourth aspect of the present application, by executing a trajectory tracking method based on steer-by-wire fault tolerance, can determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the storage medium can determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Furthermore, the storage medium can perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the faulty steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements of vehicle trajectory tracking. Furthermore, the storage medium can reduce the desired steering wheel angle and increase the desired differential yaw torque before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, thereby reducing the requirement for the steering wheel angle. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained from these drawings without any creative work.

[0049] Figure 1 This is a flow chart of a trajectory tracking method based on steer-by-wire fault tolerance disclosed in an embodiment of the present application;

[0050] Figure 2 1 is a schematic structural diagram of a trajectory tracking device based on steer-by-wire fault tolerance disclosed in an embodiment of the present application;

[0051] Figure 3 This is a structural diagram of an electronic device disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0053] Steer-by-wire technology decouples the steering wheel from the steering wheel, facilitating the implementation of autonomous driving. By eliminating numerous steering transmission mechanisms, steer-by-wire systems offer the advantages of accurate and rapid response. Furthermore, vehicle electrification is driving the development of distributed drive vehicles. The combination of steer-by-wire and drive-by-wire systems transforms the entire vehicle into a typical overdrive system. By enabling mutual compensation between the drive system's actuators, the system's fault tolerance can be significantly improved.

[0054] However, existing research on using differential yaw torque to track and control vehicle trajectory has not considered the impact of differential steering; and in existing research on differential steering, the focus is mainly on traditional vehicles rather than intelligent driving vehicles, that is, the focus is mainly on differential power steering. The few articles that study differential steering do not fully utilize the differential yaw torque generated during differential steering, and even regard it as a negative effect (affecting vehicle stability).

[0055] To address the above technical issues, embodiments of the present application provide a trajectory tracking method, apparatus, device, and medium based on steer-by-wire fault tolerance. When a steering actuator motor fails, the method determines desired control parameters for vehicle trajectory tracking, including a desired steering wheel angle and a desired differential yaw torque. The method then determines the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Trajectory tracking is then performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. When the steer-by-wire system fails, the front axle differential steering torque is used to assist the faulty steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, the method reduces the desired steering wheel angle and increases the desired differential yaw torque before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, thereby reducing the steering wheel angle requirement. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0056] Specifically, see Figure 1 , Figure 1 This is a flow chart of a trajectory tracking method based on wire-controlled steering fault tolerance disclosed in an embodiment of the present application. Figure 1 As shown, the trajectory tracking method based on steer-by-wire fault tolerance in an embodiment of the present application includes the following steps:

[0057] 101. When a steering actuator motor fails, determining desired control parameters for vehicle trajectory tracking, the desired control parameters including a desired steering wheel angle and a desired differential yaw torque;

[0058] 102. Reduce the desired steering wheel angle and increase the desired differential yaw moment;

[0059] 103. Determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle;

[0060] 104. Perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

[0061] The method of the embodiment of the present application can determine the desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include the desired steering wheel angle and the desired differential yaw torque. Furthermore, the front axle differential steering torque and the output torque of the steering actuator motor can be determined based on the desired steering wheel angle. Furthermore, trajectory tracking can be performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the failed steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, the desired steering wheel angle can be reduced and the desired differential yaw torque increased, thereby reducing the requirement for the steering wheel angle. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0062] In the embodiments of this application, the steering actuator motor refers to a steer-by-wire (SBW) motor, which is electronically controlled, has no mechanical connection, and is driven by electrical signals. On the other hand, the steering actuator motor is part of a steer-by-wire system, that is, the steer-by-wire system includes the steering actuator motor and other components, which may be a controller.

[0063] In the embodiment of the present application, the expected control parameters for vehicle trajectory tracking refer to the control parameters required to achieve the expected trajectory tracking effect. In addition to the vehicle position error and the vehicle heading angle error, the expected control parameters may also include other parameters, which are not elaborated in the embodiment of the present application.

[0064] In the embodiment of the present application, the desired differential yaw moment includes the desired front axle differential yaw moment and the rear axle differential yaw moment, wherein the differential yaw moment is the difference in driving force or braking force between the left and right wheels.

[0065] In the embodiment of the present application, during the trajectory tracking process, the differential yaw torque and the front axle differential steering torque can both affect the steering and stability control of the vehicle. By adjusting the work share of the two, the demand for the front axle differential steering torque can be reduced while achieving the same control effect, thereby reducing the demand for the desired steering angle.

[0066] In the embodiment of the present application, the front axle differential steering torque can be controlled by the output torque of the front left wheel and the front right wheel.

[0067] In an embodiment of the present application, a method for determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle is as follows:

[0068] The ratio of the steering function assumed by the steering actuator motor and the front axle wheels is determined according to the degree of failure of the steering actuator motor, and the expected steering wheel angle is allocated according to the ratio. The front axle differential steering torque is then determined according to the steering ratio corresponding to the front axle wheels, and the output torque of the steering actuator motor is determined according to the steering ratio corresponding to the steering actuator motor.

[0069] In an embodiment of the present application, as an optional implementation, trajectory tracking is performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor, including the following steps:

[0070] Determining the output torque of the front axle hub motor and the output torque of the rear axle hub motor based on the front axle differential steering torque and the desired differential yaw torque;

[0071] Trajectory tracking is performed based on the output torque of the steering actuator motor, the output torque of the front axle hub motor, and the output torque of the rear axle hub motor.

[0072] This optional implementation can determine the output torque of the front axle hub motor and the output torque of the rear axle hub motor based on the front axle differential steering torque and the desired differential yaw torque, and then can perform trajectory tracking based on the output torque of the steering execution motor, the output torque of the front axle hub motor and the output torque of the rear axle hub motor.

[0073] In the above optional embodiment, a specific method for determining the output torque of the front axle hub motor and the output torque of the rear axle hub motor based on the front axle differential steering torque and the expected differential yaw torque is:

[0074] Determine the output torque of the front axle hub motor according to the front axle differential steering torque and the front axle differential yaw torque;

[0075] The output torque of the rear axle hub motor is determined according to the rear axle differential yaw torque.

[0076] In the embodiment of the present application, as an optional implementation, reducing the desired steering wheel angle and increasing the desired differential yaw moment includes the following steps:

[0077] Determine the degree of failure of the steering actuator motor;

[0078] determining a weight coefficient of a desired steering wheel angle and a weight coefficient of a desired differential yaw moment based on a fault degree of the steering actuator motor, wherein the weight coefficient of the desired steering wheel angle increases as the fault degree of the steering actuator motor increases;

[0079] The desired steering wheel angle is reduced and the desired differential yaw moment is increased based on the weight coefficient of the desired steering wheel angle and the weight coefficient of the desired differential yaw moment.

[0080] This optional embodiment determines the degree of failure of the steering actuator motor, and then determines the weight coefficient of the expected steering wheel angle and the weight coefficient of the expected differential yaw torque based on the degree of failure of the steering actuator motor, wherein the weight coefficient of the expected steering wheel angle increases with the increase in the degree of failure of the steering actuator motor, thereby reducing the expected steering wheel angle and increasing the expected differential yaw torque based on the weight coefficient of the expected steering wheel angle and the weight coefficient of the expected differential yaw torque.

[0081] In this optional embodiment, the degree of failure of the steering actuator motor represents the failure level of the steering actuator motor, wherein the degree of failure of the steering actuator motor can be divided into complete damage and partial damage. When the degree of failure of the steering actuator motor is partial damage, the reduction in the steering wheel angle is expected to be smaller, and if the degree of failure of the steering actuator motor is complete damage, the reduction in the steering wheel angle is expected to be larger.

[0082] In this optional implementation, the sum of the weight coefficient of the desired steering wheel angle and the weight coefficient of the desired differential yaw moment is 1.

[0083] In an embodiment of the present application, as an optional implementation, determining the fault degree of the steering actuator motor includes the following steps:

[0084] Obtaining a torque sensor detection signal of a steering actuator motor;

[0085] determining the efficiency of the steering actuator motor based on a detection signal from a torque sensor of the steering actuator motor;

[0086] The degree of failure of the steering actuating motor is determined based on the effectiveness of the steering actuating motor.

[0087] This optional implementation method obtains the torque sensor detection signal of the steering actuator motor, and then can determine the efficiency of the steering actuator motor based on the torque sensor detection signal of the steering actuator motor, thereby determining the degree of failure of the steering actuator motor based on the efficiency of the steering actuator motor.

[0088] In this optional embodiment, the torque sensor of the steering actuator motor may be a strain gauge torque sensor, wherein a strain gauge may be attached to the steering shaft of the steering actuator motor, and the torque may be measured by the deformation of the strain gauge.

[0089] In this optional embodiment, the efficiency of the steering actuator motor refers to the ratio of the current torque to the full output torque of the steering actuator motor.

[0090] In an embodiment of the present application, as an optional implementation, determining the front axle differential steering torque based on the expected steering wheel angle includes the following steps:

[0091] When the steering actuator motor is in a complete failure, the front axle differential steering torque is determined based on the desired steering wheel angle.

[0092] This optional implementation can, when the steering actuator motor is in complete failure, expect that the steering wheel angle is entirely used to determine the front axle differential steering torque, so that the front axle differential steering torque bears all steering requirements.

[0093] In an optional embodiment, the desired steering wheel angle is entirely used to determine the front axle differential steering torque, which means that the desired steering wheel angle is achieved only by the front axle differential steering torque without the steering actuator motor taking on the steering demand.

[0094] In this optional embodiment, if the steering actuator motor partially fails, the desired steering wheel angle is tracked jointly by the output torque of the steering actuator motor and the front axle differential steering torque.

[0095] In an embodiment of the present application, as an optional implementation, determining desired control parameters for vehicle trajectory tracking includes the following steps:

[0096] Acquiring vehicle parameters, wherein the vehicle parameters include vehicle position error and vehicle heading angle error;

[0097] Desired control parameters are determined based on the vehicle position error and the vehicle heading angle error.

[0098] This optional implementation can obtain vehicle parameters, wherein the vehicle parameters include a vehicle position error and a vehicle heading angle error, and then can determine desired control parameters based on the vehicle position error and the vehicle heading angle error.

[0099] In this optional embodiment, the vehicle position error refers to the difference between the current position of the vehicle and a preset position, wherein the preset position is generated based on the control instruction.

[0100] In this optional embodiment, the vehicle heading angle error refers to the deviation between the actual heading angle of the vehicle and the expected heading angle.

[0101] In an embodiment of the present application, as an optional implementation, determining the desired control parameter based on the vehicle position error and the vehicle heading angle error includes the following steps:

[0102] Get boundary conditions;

[0103] Determine the desired control parameters based on the vehicle position error, vehicle heading angle error, and boundary conditions.

[0104] This optional implementation can obtain boundary conditions and then determine desired control parameters based on the vehicle position error, vehicle heading angle error, and boundary conditions.

[0105] In this optional embodiment, the boundary condition may be a constraint condition of the input item, for example, it may be a constraint adjustment of the desired steering wheel.

[0106] See also Figure 2 , Figure 2 Schematic diagram of a trajectory tracking device based on wire-controlled steering fault tolerance provided by an embodiment of the present application. Figure 2 As shown, the device of the embodiment of the present application includes the following functional modules:

[0107] A first determination module 201 is configured to determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails, the desired control parameters including a desired steering wheel angle and a desired differential yaw moment;

[0108] an adjustment module 202 for reducing a desired steering wheel angle and increasing a desired differential yaw moment;

[0109] A second determining module 203 is configured to determine a front axle differential steering torque and an output torque of a steering actuator motor based on a desired steering wheel angle;

[0110] The control module 204 is configured to perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

[0111] The device of the embodiment of the present application can determine the desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include the desired steering wheel angle and the desired differential yaw torque. Based on the desired steering wheel angle, the device can then determine the front axle differential steering torque and the output torque of the steering actuator motor. Furthermore, based on the front axle differential steering torque, the device can perform trajectory tracking based on the desired differential yaw torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the device can utilize the front axle differential steering torque to assist the failed steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, the device can first reduce the desired steering wheel angle and increase the desired differential yaw torque, thereby reducing the requirement for the steering wheel angle. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0112] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of an electronic device disclosed in an embodiment of the present application. Figure 3 As shown, the electronic device of the embodiment of the present application includes:

[0113] Processor 301; and

[0114] The memory 302 is configured to store machine-readable instructions, which, when executed by the processor 301 , execute the trajectory tracking method based on steer-by-wire fault tolerance as described in any of the aforementioned embodiments.

[0115] The electronic device of the present invention, by executing a steer-by-wire fault-tolerant trajectory tracking method, can determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the electronic device can determine the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle. Furthermore, trajectory tracking can be performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the faulty steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements for vehicle trajectory tracking. Furthermore, before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, the electronic device can reduce the desired steering wheel angle and increase the desired differential yaw torque, thereby reducing the steering wheel angle requirement. This reduces the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0116] An embodiment of the present application discloses a storage medium storing a determination machine program, and the determination machine program is executed by a processor to implement a trajectory tracking method based on wire control steering fault tolerance as described in any of the aforementioned embodiments.

[0117] The storage medium of the embodiment of the present application, by executing a trajectory tracking method based on steer-by-wire fault tolerance, can determine the desired control parameters for vehicle trajectory tracking when a steering actuator motor fails. The desired control parameters include a desired steering wheel angle and a desired differential yaw torque. Furthermore, the front axle differential steering torque and the output torque of the steering actuator motor can be determined based on the desired steering wheel angle. Furthermore, trajectory tracking can be performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor. Thus, when a steer-by-wire system fails, the front axle differential steering torque is used to assist the faulty steer-by-wire system in smoothly tracking the desired steering wheel angle, thereby achieving the steering requirements of vehicle trajectory tracking. Furthermore, before determining the front axle differential steering torque and the output torque of the steering actuator motor based on the desired steering wheel angle, the desired steering wheel angle can be reduced and the desired differential yaw torque can be increased, thereby reducing the requirement for the steering wheel angle. This eliminates the need for the front axle to output excessively high drive torque to achieve a larger differential steering torque, thereby preventing excessive drive torque from affecting vehicle tracking stability.

[0118] With respect to the embodiments of the present application, as an example, a trajectory tracking method based on steer-by-wire fault tolerance includes:

[0119] The ECU reads the vehicle speed, yaw rate, sideslip angle of the vehicle's center of mass, the steering execution motor output torque and the steering wheel angle signal.

[0120] During the system self-test, the ECU reads the self-test signal of the steering actuator motor and outputs the steering actuator motor efficiency signal: The ECU reads the torque signal output by the steering actuator motor torque sensor and determines the steering actuator motor efficiency according to the following formula:

[0121]

[0122] Among them, λ is the steering actuator motor efficiency, τ sm The actual output torque of the steering actuator motor measured by the steering actuator motor torque sensor, τ sm,d is the desired output torque of the steering actuator motor. If λ = 1, the steering actuator motor is in good condition. If 0 < λ < 1, it indicates a partial failure of the steering actuator motor. For example, if λ = 0.7, the steering actuator motor has lost 30% of its control efficiency and can only output 70% of the torque compared to its normal state. If λ = 0, the steering actuator motor has completely failed and can no longer output torque to drive the steering wheel.

[0123] The ECU calls the distributed drive intelligent driving vehicle trajectory tracking state space equations and differential cooperative wire control steering state space equations stored in it. Further, the trajectory tracking state space equations refer to:

[0124]

[0125] Among them, the state vector Output vector Input vector U = [δ fw ,M z ] T , A err 、B err 、C err and W err are coefficient matrices, which are:

[0126]

[0127]

[0128] Among them, e d is the position error, is the heading error, m is the vehicle mass, v x is the longitudinal velocity of the vehicle body, I z is the moment of inertia of the vehicle around the z-axis, a is the distance from the center of mass of the vehicle to the front axle, b is the distance from the center of mass of the vehicle to the rear axle, C f is the vehicle front axle lateral stiffness, C r is the vehicle rear axle cornering stiffness, δ fw is the vehicle steering wheel angle, M z is the total differential yaw torque output from the front and rear axles;

[0129] Furthermore, the differential cooperative steer-by-wire state space equation is:

[0130]

[0131] Among them, the state vector Output vector Y = [δ fw ], input vector U=[τ sm ,ΔT f ] T , A sbw 、B sbw 、C sbw is the coefficient matrix, D sbw are interference matrices, which are:

[0132]

[0133] C sbw =[1 0];

[0134]

[0135] Among them, J fw is the steering wheel moment of inertia, J sm is the moment of inertia of the steering actuator motor, r is the conversion coefficient from the rack translation motion of the rack and pinion steering gear to the steering wheel rotation, N1 is the number of meshing teeth of the steering gear of the rack and pinion steering gear, N2 is the number of meshing teeth of the rack of the rack and pinion steering gear, B fw is the steering wheel damping coefficient, N s is the steering system angular transmission ratio, B sm The damping coefficient of the steering actuator motor, r σ is the lateral offset of the kingpin of the steering wheel, r w is the rolling radius of the steering wheel, t m +t p Indicates the sum of the tire castor trail and the pneumatic tire trail, ΔT f is the front axle differential steering torque, AT * is the term in the steering wheel positive torque that is independent of the steering wheel angle, J eq is the equivalent moment of inertia of the steering system, B eq is the equivalent damping of the steering system, C fw is the equivalent friction coefficient of the steering wheel.

[0136] Furthermore, the ECU invokes an upper-level controller control module in the steer-by-wire fault-tolerant control method for a distributed drive intelligent vehicle, performs control based on the vehicle trajectory tracking state-space equation, inputs the vehicle position error and heading angle error, and outputs the desired steering wheel angle and the desired total differential yaw torque output by the front and rear axle hub motors. Preferably, the upper-level controller in the upper-level controller control module uses a Model Predictive Control (MPC).

[0137] Furthermore, the state space equation is used to describe the characteristics of the controlled object:

[0138]

[0139] Where x is the system state, u is the system input, y is the system output, A is the system state transfer matrix, B is the input matrix, C is the output matrix, and d is the nonlinear deviation matrix.

[0140] Assuming that the current time is k, the upper controller control module converts the trajectory tracking state space equation of the distributed drive intelligent driving vehicle into a discrete form:

[0141]

[0142] Where T is the sampling time, the above equation can be organized into a discretized state space equation:

[0143]

[0144] Where A k =A*T+I,B k =B*T,d k =x(k+1)-A k x(k)-B k u(k), I is the identity matrix.

[0145] Next, in the prediction time domain N p Predict the motion response of the system

[0146]

[0147] y(k+i|k)=Cx(k+i|k);

[0148] Where N c For the control time domain, x(k+i|k), u(k+i|k), y(k+i|k) represent the prediction of the system state, input and output at the kth moment, x(k|k) = x(k).

[0149] Rearranging the above formula yields:

[0150]

[0151] Where Y is the output matrix in the prediction time domain, U is the control time domain N c The input matrix in ΔU is N c The input increment matrix within,

[0152]

[0153]

[0154] Next is the rolling optimization part. In order to make the vehicle accurately track the desired trajectory using the lowest possible input, the cost function J is established here:

[0155] J=Y T QY+ΔU T RΔU+U T WU;

[0156] Where Q, R, and W are the output error term, the input term increment, and the weight coefficient matrix of the input term. W is set to prevent the error from not converging due to the mutual balance of the two input terms.

[0157] Furthermore, in order to reduce the workload of the lower-level controller when the steering execution motor fails, the collaborative control strategy of the present invention will adjust the R of the upper-level controller in real time. Preferably, in this embodiment, the design of the input vector weight matrix R adopts fuzzy control algorithm design.

[0158] The adjustment idea of ​​R is as follows: when the fault of the wire-controlled steering motor becomes more serious, the upper controller will reduce the steering wheel angle requirement of the faulty wire-controlled steering system by utilizing the influence of the differential yaw torque generated by the driving torque difference between the left and right wheels on the vehicle movement. That is, the weight coefficient of the steering wheel angle input item increases as the fault of the wire-controlled steering system becomes more serious. d When it is large, it means that the trajectory tracking effect is poor, and the weight coefficient of the input item needs to be reduced to ensure the trajectory tracking effect.

[0159] Arranged:

[0160]

[0161] Where H is irrelevant to the input term U. Ignore H and then set:

[0162]

[0163] The cost function J can be organized as:

[0164] J=U T MU+2NU

[0165] The steering motion of the vehicle must meet the constraints of the steering system. That is, there are limits on the magnitude of the steering wheel angle and the differential yaw moment. At the same time, there are limits on the speed increase of the steering wheel angle and the differential yaw moment. The constraints are:

[0166]

[0167] Where U min ,U max is the minimum and maximum value of the input item, ΔU min ,ΔU max The minimum and maximum values ​​for the input item increment.

[0168] Finally, the upper controller control module optimizes J considering the boundary conditions and finds the optimal solution That is, under the current working conditions, the expected steering wheel angle and the total differential yaw torque output from the front and rear axles.

[0169] It should be noted that the upper-level controller of the embodiment of the present application is not limited to this type of MPC controller and fuzzy control algorithm, and other types of controllers can also be designed as needed. This does not constitute a limitation on the scope of protection of the present invention.

[0170] Furthermore, the ECU calls the lower-level controller control module in the wire-steering fault-tolerant control method of the distributed drive intelligent driving vehicle, performs control according to the differential cooperative wire-steering state space equation, inputs the desired steering wheel angle output by the upper-level controller, and outputs the desired output torque of the steering execution motor and the desired differential steering torque output by the front axle hub motor.

[0171] When the steer-by-wire motor is intact or partially faulty, the lower-level controller leverages the difference in drive torque between the left and right front axle wheels to generate a front axle differential steering torque that affects the vehicle's steering wheel angle, assisting the steering actuator motor in driving the steering wheel. If the steer-by-wire motor fails completely, the front axle differential steering torque assumes full responsibility for steering wheel deflection. In this embodiment, the lower-level controller's control module also utilizes the MPC control algorithm and fuzzy algorithm for steering wheel angle tracking and weighting between differential steering and steer-by-wire. The detailed process is not detailed here.

[0172] Furthermore, the ECU controls the output torque of the steering actuator motor, the front axle hub motor and the rear axle hub motor according to the output results of the upper controller control module and the lower controller control module to complete the vehicle steering movement.

[0173] The output torque of the four wheel hub motors is determined according to the following formula:

[0174]

[0175] T i (i=1, 2, 3, 4) are the driving torques of the left front wheel, left rear wheel, right front wheel, and right rear wheel, B0 is the vehicle wheelbase, and T is the total required driving torque.

[0176] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interface, the indirect coupling or communication connection of the device or unit can be electrical, mechanical or other forms.

[0177] In addition, the units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0178] Furthermore, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0179] It should be noted that if the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a determination machine readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the determination machine software product is stored in a storage medium, including a number of instructions for enabling a determination machine device (which can be a personal determination machine, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM) random access memory (RAM), disk or optical disk and other media that can store program code.

[0180] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0181] The above are merely examples of the present application and are not intended to limit the scope of protection of the present application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A trajectory tracking method based on steer-by-wire fault tolerance, characterized in that: The method comprises: When the steering actuator motor fails, determining desired control parameters for vehicle trajectory tracking, the desired control parameters including a desired steering wheel angle and a desired differential yaw moment; reducing the desired steering wheel angle and increasing the desired differential yaw moment; determining a front axle differential steering torque and an output torque of the steering actuator motor based on the desired steering wheel angle; Trajectory tracking is performed based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

2. The method according to claim 1, wherein The performing trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor includes: determining an output torque of the front axle wheel hub motor and an output torque of the rear axle wheel hub motor based on the front axle differential steering torque and the desired differential yaw torque; Trajectory tracking is performed based on the output torque of the steering actuator motor, the output torque of the front axle hub motor, and the output torque of the rear axle hub motor.

3. The method according to claim 1, wherein The reducing the desired steering wheel angle and increasing the desired differential yaw moment includes: determining a fault degree of the steering actuator motor; determining a weight coefficient of the desired steering wheel angle and a weight coefficient of the desired differential yaw moment based on the degree of failure of the steering actuator motor, wherein the weight coefficient of the desired steering wheel angle increases as the degree of failure of the steering actuator motor increases; The desired steering wheel angle is reduced and the desired differential yaw moment is increased based on a weight coefficient of the desired steering wheel angle and a weight coefficient of the desired differential yaw moment.

4. The method according to claim 3, wherein Determining the fault degree of the steering actuator motor includes: Acquiring a torque sensor detection signal of the steering actuator motor; determining the efficiency of the steering actuator motor based on a detection signal of a torque sensor of the steering actuator motor; A degree of failure of the steering actuating motor is determined based on the effectiveness of the steering actuating motor.

5. The method according to claim 1, wherein The determining of the front axle differential steering torque based on the expected steering wheel angle includes: When the steering actuator motor is in a complete failure, the front axle differential steering torque is determined based on a desired steering wheel angle.

6. The method according to claim 1, wherein The determining of desired control parameters for vehicle trajectory tracking includes: Acquiring vehicle parameters, wherein the vehicle parameters include vehicle position error and vehicle heading angle error; The desired control parameter is determined based on the vehicle position error and the vehicle heading angle error.

7. The method according to claim 6, wherein The determining the desired control parameter based on the vehicle position error and the vehicle heading angle error includes: Get boundary conditions; The desired control parameter is determined based on the vehicle position error, the vehicle heading angle error, and the boundary conditions.

8. A trajectory tracking device based on steer-by-wire fault tolerance, characterized in that: The device comprises: a first determining module, configured to determine desired control parameters for vehicle trajectory tracking when a steering actuator motor fails, the desired control parameters including a desired steering wheel angle and a desired differential yaw moment; an adjusting module, configured to reduce the desired steering wheel angle and increase the desired differential yaw moment; a second determining module, configured to determine a front axle differential steering torque and an output torque of the steering execution motor based on the desired steering wheel angle; A control module is configured to perform trajectory tracking based on the front axle differential steering torque, the desired differential yaw torque, and the output torque of the steering actuator motor.

9. An electronic device, characterized in that: include: processor; as well as A memory configured to store machine-readable instructions, wherein when the instructions are executed by the processor, the method for trajectory tracking based on steer-by-wire fault tolerance is executed.

10. A storage medium, characterized in that: The storage medium stores a determination machine program, and the determination machine program is executed by a processor to implement the trajectory tracking method based on wire control steering fault tolerance according to any one of claims 1 to 7.

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