CN-119611495-B - Vehicle steering control method, vehicle steering system and vehicle

Abstract

The invention discloses a vehicle steering control method, a vehicle steering system and a vehicle, wherein the vehicle comprises a distributed driving system, the vehicle steering control method comprises the steps of determining steering wheel angle errors according to steering wheel target angles and steering wheel actual angles, determining steering wheel target differential moments according to the steering wheel angle errors, and controlling driving motors corresponding to steering wheels in the distributed driving system according to the steering wheel target differential moments so as to distribute the steering wheel target differential moments to the steering wheels. The method and the system can solve the problem of inaccurate steering possibly caused by the fault condition of the vehicle steering system, and have the advantages of no need of adding extra hardware, low manufacturing cost, simple vehicle structure and control design and space saving.

Inventors

• LI HONGFEI
• LU GUOXIANG
• ZHUANG XULI
• GUO KAI
• ZHU XIAOJUN

Assignees

• 比亚迪股份有限公司

Dates

Publication Date

20260505

Application Date

20230913

Claims (19)

1. 1. A vehicle steering control method is characterized in that the vehicle comprises a distributed driving system, a yaw control system and a driving anti-skid system, the vehicle steering control method is used for an automatic driving mode, and comprises the following steps: Determining a steering wheel angle error according to a steering wheel target angle and a steering wheel actual angle, determining a steering wheel target differential moment according to the steering wheel angle error, determining a yaw control compensation moment, and obtaining a slip limit compensation moment; Controlling a driving motor of a corresponding steering wheel in the distributed driving system according to the steering wheel target differential moment to distribute the steering wheel target differential moment to the steering wheel, and distributing a yaw control compensation moment according to an activated state of the yaw control system, wherein the yaw control compensation moment is distributed to non-steering wheels when the yaw control system of the vehicle is not activated, and the slip limit compensation moment is distributed according to an activated state of the driving anti-slip system, wherein torque limitation is performed on each wheel according to the slip limit compensation moment when the driving anti-slip system of the vehicle is not activated; When the yaw control system and the driving anti-skid system of the vehicle are activated, the steering wheel target differential moment distributed by each wheel is directly transmitted to each driving motor; when the yaw control system is activated and the driving anti-skid system is not activated, vector superposition is carried out on the target differential moment of the steering wheel and the slip limit compensation moment; when the yaw control system is not activated and the anti-skid system is driven to be activated, vector superposition is carried out on the steering wheel target differential moment and the yaw control compensation moment; And vector superposition is carried out on the slip limit compensation moment, the yaw control compensation moment and the steering wheel target differential moment when the yaw control system and the driving anti-skid system are not activated.
2. 2. The vehicle steering control method according to claim 1, characterized in that the determining the yaw control compensation moment includes: obtaining an ideal yaw rate according to the target steering wheel angle and the reference vehicle speed of the vehicle; obtaining yaw rate deviation according to the ideal yaw rate and the actual yaw rate; And obtaining a yaw control compensation moment according to the yaw rate deviation.
3. 3. The vehicle steering control method according to claim 1, characterized in that the vehicle steering control method further comprises: acquiring a reference vehicle speed of the vehicle; and determining the steering wheel target differential moment according to the steering wheel angle error and the reference vehicle speed of the vehicle.
4. 4. The vehicle steering control method according to claim 3, characterized in that determining the steered wheel target differential torque from the steering wheel angle error and a reference vehicle speed of the vehicle includes: Inquiring a mapping relation according to the steering wheel angle error and the reference vehicle speed to obtain the steering wheel target differential moment, wherein the mapping relation is a corresponding relation of the steering wheel angle error, the reference vehicle speed and the steering wheel target differential moment; or the steering wheel target differential moment is obtained according to the steering wheel angle error, the reference vehicle speed and the steering part parameter calculation of the vehicle.
5. 5. The vehicle steering control method according to claim 1, characterized in that controlling a drive motor of a corresponding steered wheel in the distributed drive system according to the steered wheel target differential torque to distribute the steered wheel target differential torque to the steered wheel, includes: And controlling two driving motors corresponding to two steering wheels in the distributed driving system according to the steering wheel target differential moment so as to evenly distribute the steering wheel target differential moment to the two steering wheels.
6. 6. The vehicle steering control method according to claim 5, characterized in that the controlling of the two drive motors of the distributed drive system corresponding to the two steered wheels according to the steered wheel target differential torque includes: If the moment after the vector superposition of the first wheel in the coaxial two wheels does not exceed the first execution limit value of the first wheel, maintaining the moment of the first wheel unchanged; if the moment after the vector superposition of the first wheel exceeds the first execution limit value, the first execution limit value is distributed to the first wheel, and a moment difference value between the moment after the vector superposition of the first wheel and the first execution limit value is distributed to a second wheel in the coaxial two wheels; If the moment difference is distributed to the second wheel, and the total moment distributed by the second wheel does not exceed the second execution limit value of the second wheel, controlling the driving motors corresponding to the coaxial two wheels according to the distributed moment; And if the moment difference is distributed to the second wheel, and the total moment distributed by the second wheel exceeds the second execution limit value, controlling the driving motor corresponding to the second wheel according to the second execution limit value.
7. 7. The vehicle steering control method according to claim 3, characterized in that, The distributed driving system comprises a left front driving motor, a left rear driving motor, a right rear driving motor and a right front driving motor; The reference vehicle speed is obtained according to rotational speed information of the front left drive motor, the rear right drive motor and the front right drive motor and inertia information of the vehicle.
8. 8. The vehicle steering control method according to claim 3, characterized in that the obtaining slip limit compensation torque includes: calculating the slip rate of each wheel according to the reference vehicle speed; The slip limit compensation torque is obtained according to the reference vehicle speed and the slip ratio, or the slip limit compensation torque is obtained according to the slip ratio and the moment of inertia of each wheel.
9. 9. The vehicle steering control method according to any one of claims 1 to 8, characterized in that the vehicle steering control method further includes: When the vehicle is in a braking working condition, distributing braking demand torque to front and rear axles of the vehicle; and evenly distributing the braking torque distributed by the front axle and the rear axle to the corresponding wheels, wherein the braking torque comprises a motor regenerative braking torque and a braking system braking torque.
10. 10. The vehicle steering control method according to claim 9, characterized in that the controlling the drive motor of the corresponding steered wheel in the distributed drive system according to the steered wheel target differential torque to distribute the steered wheel target differential torque to the steered wheel includes: And on the basis of unchanged total braking torque of the steering shaft, the steering wheel target differential torque is evenly distributed and then is vector-added to the two steering wheels.
11. 11. The vehicle steering control method according to claim 10, characterized in that the vehicle steering control method further comprises: The absolute value of the negative moment of the wheel is reduced by reducing the absolute value of the hydraulic braking moment, and if the negative moment reduction requirement of the wheel cannot be met, the deficiency is realized by reducing the absolute value of the regenerative braking moment of the motor; Or increasing the absolute value of the negative moment of the wheels by increasing the absolute value of the regenerative braking moment of the motor, and increasing the absolute value of the hydraulic braking if the limit of the motor capacity or the battery electric quantity is received.
12. 12. A vehicle steering system, comprising: A distributed drive system for driving each wheel of the vehicle; The sensor system is used for collecting steering sensing information; a controller in communication with the distributed drive system and the sensor system for performing the vehicle steering control method of any one of claims 1-11.
13. 13. The vehicle steering system of claim 12, wherein the distributed drive system includes a front left drive motor, a rear right drive motor, and a front right drive motor.
14. 14. The vehicle steering system of claim 12, wherein the controller comprises: the automatic driving controller is used for sending out a steering control instruction in an automatic driving mode; the steering driving and controlling device is in communication connection with the automatic driving controller and is used for executing the steering control instruction; And the whole vehicle controller is in communication connection with the automatic driving controller and is used for executing the steering control instruction when the steering driving and controlling device is abnormal.
15. 15. The vehicle steering system according to claim 14, wherein the automatic driving controller includes a first controller and a second controller, one of the first controller and the second controller being a master control, the other being a slave control, the slave control taking master authority when the master control is abnormal.
16. 16. The vehicle steering system of any of claims 12-15, further comprising an ackerman steering system and a steer-by-wire system.
17. 17. The vehicle steering system of claim 16, wherein the ackerman steering system comprises: Steering wheel, steering column, universal joint, worm rack steering gear, left front steering tie rod, right front steering tie rod and steering driving and controlling device; The steering wheel, the steering column, the universal joint and the worm rack steering gear are sequentially connected to transmit torque and rotation angle applied on the steering wheel to the worm rack steering gear, drive racks of the worm rack steering gear and control movement of the left front steering tie rod and the right front steering tie rod; The steering driving and controlling device is connected with the worm-rack steering gear and is used for controlling the movement of the worm-rack steering gear rack.
18. 18. The vehicle steering system of claim 16, wherein the steer-by-wire system comprises: A left front brake assembly, a left rear brake assembly, a right front brake assembly, a left rear brake fluid transmission pipe, a right front brake fluid transmission pipe, a brake fluid supply and control device and a left front brake fluid transmission pipe; The left rear brake fluid transmission pipe, the right front brake fluid transmission pipe and the left front brake fluid transmission pipe can respectively connect the left rear brake assembly, the right front brake assembly and the left front brake assembly with the brake fluid supply and control device so as to realize transmission of brake fluid; The brake fluid supply and control device is used for controlling the braking moment of the left rear brake assembly, the right front brake assembly and the left front brake assembly.
19. 19. A vehicle comprising a vehicle steering system according to any one of claims 12-18.

Description

Vehicle steering control method, vehicle steering system and vehicle Technical Field The invention relates to the technical field of auxiliary driving, in particular to a vehicle steering control method, a vehicle steering system and a vehicle. Background The reliability and accuracy of the vehicle steering system is critical to the safety and handling of the ride. For a vehicle with a distributed driving system, when the steering system of the vehicle fails, accurate steering operation cannot be realized, and serious potential safety hazards exist. In the related art, even though the accuracy of the steering operation can be improved, the structure is complicated and the cost is expensive, and thus, a steering control method is needed to solve the problem. Disclosure of Invention The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, a first object of the present invention is to provide a vehicle steering control method, which can solve the problem of inaccurate steering caused by a vehicle steering system in a fault condition, and has the advantages of no need of adding additional hardware, low manufacturing cost, simple vehicle structure and control design, and space saving. A second object of the present invention is to propose a vehicle steering system. A third object of the invention is to propose a vehicle. In order to achieve the above purpose, the vehicle steering control method according to the first aspect of the embodiment of the invention comprises a distributed driving system, wherein the vehicle steering control method comprises the steps of determining a steering wheel angle error according to a steering wheel target angle and a steering wheel actual angle, determining a steering wheel target differential moment according to the steering wheel angle error, and controlling a driving motor corresponding to a steering wheel in the distributed driving system according to the steering wheel target differential moment so as to distribute the steering wheel target differential moment to the steering wheel. According to the vehicle steering control method provided by the embodiment of the invention, based on the distributed driving system of the vehicle, the distributed driving system has the characteristic that each driving motor corresponding to the wheels can work independently, and the target differential moment of the steering wheel is controlled, so that the tracking and closed-loop control of the steering wheel angle can be realized, the problem of inaccurate steering possibly caused by the vehicle steering system under the fault condition can be solved, the steering control function is realized under the condition that no additional hardware is added, the manufacturing cost is low, the vehicle structure and control design are simplified, the occupied space is saved, and the real vehicle arrangement is facilitated. In order to achieve the above object, a vehicle steering system according to a second aspect of the present invention includes a distributed driving system for driving each wheel of a vehicle, a sensor system for acquiring steering sensing information, and a controller communicatively connected to the distributed driving system and the sensor system for performing the vehicle steering control method according to the above embodiment. According to the vehicle steering system provided by the embodiment of the invention, the distributed driving system adopts the plurality of driving motors to respectively drive each wheel of the vehicle, each driving motor has the characteristic of independent work, and the distribution and steering control of the target differential moment of the steering wheel are realized by adopting the vehicle steering control method provided by the embodiment, so that the steering control function is realized without adding extra hardware, and the plurality of driving motors control different steering wheels. In order to achieve the above object, an embodiment of a third aspect of the present invention also proposes a vehicle including the vehicle steering system described in the above embodiment. According to the vehicle disclosed by the embodiment of the invention, by adopting the vehicle steering control method, the vehicle-based distributed driving system realizes the steering control function without adding extra hardware, and the plurality of driving motors control different steering wheels, and the distributed configuration enables each steering wheel to be independently controlled, so that the redundancy of steering control is realized, the problem of inaccurate steering possibly caused by a vehicle steering system under the fault condition can be solved, the manufacturing cost is low, the vehicle structure and the control design are simple, the space is saved, and the arrangement of a real vehicle is facilitated. Additional aspects and advantages of the invention will be set forth in part in the