Rear wheel steering control method and computer readable storage medium
By adopting a rear-wheel steering control strategy based on vehicle speed and driving scenario adaptation, the problem of insufficient control of the 4WS system under multi-scenario coupling conditions is solved, and the vehicle's adaptability and driving comfort under different driving scenarios are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-03-10
AI Technical Summary
Existing 4WS systems lack effective control logic in complex operating conditions with multiple coupled scenarios, especially in scenarios such as low-speed parking on slippery roads where their adaptability is insufficient.
Based on the current vehicle speed and the driving scenario, a rear-wheel steering control strategy is designed. By linearizing the steering experience, stability, and flexibility control, the steering flexibility and stability of the vehicle under different driving scenarios are dynamically balanced. The method is implemented using a computer-readable storage medium.
It improves the vehicle's adaptability and ride comfort in different driving scenarios, and achieves stability and flexibility control in multiple scenarios.
Smart Images
Figure CN121626259A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of automobile steering, and more particularly, the application relates to a rear wheel steering control method and a computer readable storage medium. BACKGROUND
[0002] Under the background of the rapid development of automobile intelligence and active safety technology, a 4WS system (four-wheel steering system) has become a key technology for improving vehicle handling performance.
[0003] The 4WS system is the abbreviation of the "four-wheel steering system", which improves the handling and stability of the whole vehicle by allowing the rear wheels to participate in steering together with the front wheels. The four-wheel steering (4WS) system has become a leading research direction in the field of vehicle dynamics control, with the core feature of "enhanced full-speed driving performance".
[0004] The core pain points of the current 4WS control architecture include insufficient scene adaptability, and existing solutions focus on a single typical working condition (such as low-speed U-turn on dry road), and lack of effective coverage of control logic for complex working conditions coupled with multiple scenes (such as low-speed parking on wet road). SUMMARY
[0005] In view of this, the present application provides a rear wheel steering control method, which aims to improve at least one of the above problems.
[0006] Specifically, the technical scheme includes the following:
[0007] On the one hand, the application embodiment provides a rear wheel steering control method, which is specifically as follows:
[0008] (1) Adapting to the corresponding driving scene based on the current vehicle speed;
[0009] (2) Adopting a corresponding rear wheel control strategy based on the current driving scene;
[0010] Wherein, the driving scene includes: parking scene, urban low-speed commuting scene and high-speed driving scene.
[0011] In some embodiments of the application, after entering the parking scene, the rear wheel steering angle is determined based on the steering wheel angle, the rear wheel steering is controlled to be opposite to the front wheel steering, and the rear wheel steering angle is linearly and positively correlated with the steering wheel angle.
[0012] In some embodiments of the application, after entering the urban low-speed commuting scene, when the vehicle speed is greater than or equal to the corresponding side slip critical speed, the rear wheel steering and the rear wheel steering angle are controlled based on stability, and when the vehicle speed is less than the corresponding side slip critical speed, the rear wheel steering and the rear wheel steering angle are controlled based on flexibility.
[0013] In some embodiments of the present application, the current working condition is determined based on the current steering wheel angle and the rear wheel steering angle, and the critical vehicle speed of side slip in the current working condition is taken as the vehicle speed corresponding to the maximum yaw rate in the current working condition.
[0014] In some embodiments of the present application, when the current vehicle speed is less than the critical vehicle speed of side slip in the current working condition, the rear wheel steering angle is determined based on the target yaw rate, the current steering wheel angle and the vehicle speed, and the rear wheel steering is controlled to be opposite to the front wheel steering, wherein the target yaw rate is less than the maximum yaw rate in the corresponding working condition.
[0015] In some embodiments of the present application, when the current vehicle speed is greater than or equal to the critical vehicle speed of side slip in the current working condition, the current rear wheel steering angle is calculated based on the vehicle dynamics model under the steady state condition, and the rear wheel steering is controlled to be the same as the front wheel steering.
[0016] In some embodiments of the present application, after entering the high-speed driving scene, the rear wheel steering angle is calculated based on the vehicle dynamics model under the steady state condition, and the rear wheel steering is controlled to be the same as the front wheel steering.
[0017] In some embodiments of the present application, when the current vehicle speed is greater than or equal to the characteristic vehicle speed, the high-speed driving scene is entered, wherein the characteristic vehicle speed is calculated as follows:
[0018]
[0019] wherein, denotes the wheelbase of the vehicle, , denote the front wheel cornering stiffness and the rear wheel cornering stiffness of the vehicle, respectively; , denote the distance from the center of mass of the vehicle to the front axle and the distance from the center of mass of the vehicle to the rear axle, respectively; denotes the total mass of the vehicle.
[0020] In some embodiments of the present application, the vehicle dynamics model under the steady state condition is as follows:
[0021]
[0022]
[0023] wherein, denotes the wheelbase of the vehicle, , denote the front wheel steering angle and the rear wheel steering angle of the vehicle, respectively; , denote the front wheel cornering stiffness and the rear wheel cornering stiffness of the vehicle, respectively; denotes the longitudinal vehicle speed. Indicates the vehicle's yaw angle; , These represent the distances from the vehicle's center of gravity to the front axle and from the center of gravity to the rear axle, respectively. Indicates the overall vehicle weight.
[0024] On the other hand, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, characterized in that the program, when executed by a processor, implements the rear wheel steering control method as described above.
[0025] This invention adapts to different driving scenarios based on driving speed, and designs corresponding rear-wheel control strategies for different driving scenarios to dynamically balance the vehicle's steering flexibility and driving stability, thereby improving the vehicle's adaptability and driving comfort in different driving scenarios. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 A flowchart of the rear wheel steering control method provided in an embodiment of the present invention;
[0028] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation
[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0030] Unless otherwise defined, all technical terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art.
[0031] Figure 1 The following is a flowchart of the rear wheel steering control method provided in an embodiment of the present invention. The method is as follows:
[0032] (1) Adapt the corresponding driving scenario based on the vehicle's current speed;
[0033] This invention divides driving scenarios into parking scenarios, urban low-speed commuting scenarios, and high-speed driving scenarios based on vehicle speed. The specific speed ranges corresponding to the above three driving scenarios are as follows: when the current vehicle speed is less than 10km / h, the vehicle enters the parking scenario; when the current vehicle speed is greater than 10km / h but less than the characteristic vehicle speed, the vehicle enters the urban low-speed commuting scenario; and when the current vehicle speed is greater than the characteristic vehicle speed, the vehicle enters the high-speed driving scenario.
[0034] (2) Based on the current driving scenario, the corresponding rear wheel control strategy is adopted. The rear wheel control strategies for the three driving scenarios are explained in detail below:
[0035] (21) Parking scenario: The rear wheel steering angle is determined based on the steering wheel angle, and the rear wheel steering is controlled to be opposite to the front wheel steering. The rear wheel steering angle is linearly positively correlated with the steering wheel angle.
[0036] The rear wheel steering angle corresponding to the steering wheel angle when the steering wheel is fully turned is set as the maximum rear wheel steering angle, and the rear wheel steering angle when the steering wheel is centered is set to zero. A linear relationship between the rear wheel steering angle and the steering wheel angle is established. The current steering wheel angle of the vehicle is collected, and the rear wheel steering angle corresponding to the current steering wheel angle is calculated as the current rear wheel steering angle of the vehicle. The rear wheel steering is controlled to be opposite to the front wheel steering, so as to achieve a linear experience of "linear steering input - linear vehicle response".
[0037] (22) In urban low-speed commuting scenarios, the rear wheel steering angle and rear wheel steering are mainly controlled based on the sideslip critical speed. When the vehicle speed is greater than the corresponding sideslip critical speed, the rear wheel steering and rear wheel steering angle are controlled based on stability. When the vehicle speed is less than the corresponding sideslip critical speed, the rear wheel steering and rear wheel steering angle are controlled based on flexibility.
[0038] Theoretically, vehicle speed is directly proportional to yaw rate. After reaching the critical speed for sideslip under the current operating condition, the yaw rate decreases as the vehicle speed continues to increase. Therefore, the yaw rate initially increases and then decreases under a given operating condition. The vehicle speed corresponding to the maximum yaw rate under the current operating condition is taken as the critical speed for sideslip. If the vehicle speed is less than the critical speed for sideslip under the current operating condition, there is no risk of sideslip, and the focus is on the vehicle's steering agility. If the vehicle speed is greater than the critical speed for sideslip under the current operating condition, there is a risk of sideslip, and the focus is on the stability of the vehicle's control speed. Therefore, the specific process of controlling the rear wheel steering angle is as follows:
[0039] (221) Determine the current working condition based on the current steering wheel angle and rear wheel steering angle, and take the vehicle speed corresponding to the maximum yaw rate under the current working condition as the critical speed for sideslip under the current working condition.
[0040] (222) When the current vehicle speed is less than the critical speed for sideslip under the current operating condition, the rear wheel steering angle is determined based on the target yaw rate, the current steering wheel angle and the vehicle speed, and the rear wheel steering is controlled to be opposite to the front wheel steering. When the current vehicle speed is greater than or equal to the critical speed for sideslip under the current operating condition, the current rear wheel steering angle is calculated based on the vehicle dynamics model under steady-state conditions, and the rear wheel steering is controlled to be in the same direction as the front wheel steering. The target yaw rate is a set value, which is less than the maximum yaw rate under the corresponding operating condition.
[0041] In this embodiment of the invention, before controlling the rear wheel steering angle in urban low-speed commuting scenarios, it is necessary to calibrate the mapping table of yaw rate corresponding to different steering wheel angles, vehicle speeds, and rear wheel steering angles. The calibration process is as follows:
[0042] Under specified operating conditions, when the vehicle speed is less than the critical speed for sideslip, the yaw rate at different speeds is calibrated using a real vehicle. When the vehicle sideslips, the yaw rate at other speeds is calibrated based on Carsim dynamics simulation. By changing the steering wheel angle or rear wheel steering angle, the operating conditions are changed, and the yaw rate at different speeds under various operating conditions is calibrated. A mapping table of yaw rates corresponding to different steering wheel angles, vehicle speeds, and rear wheel steering angles is constructed.
[0043] The rear wheel steering in step (222) and the critical speed for sideslip in the current condition in step (221) are determined based on the mapping table of steering wheel angle, vehicle speed and rear wheel steering angle corresponding to the yaw rate.
[0044] In this embodiment of the invention, the vehicle dynamics model under steady-state conditions is shown in formulas (3) and (4), and the specific process for obtaining it is as follows:
[0045] In this embodiment of the invention, the 4WS two-degree-of-freedom vehicle dynamics model is shown in the following formulas (1) and (2):
[0046] (1)
[0047] (2)
[0048] in, , These represent the front wheel steering angle and the rear wheel steering angle of the vehicle, respectively. , These represent the front wheel lateral stiffness and the rear wheel lateral stiffness of the vehicle, respectively. Indicates the vehicle's longitudinal speed; Indicates the vehicle's yaw angle; , These represent the distances from the vehicle's center of gravity to the front axle and from the center of gravity to the rear axle, respectively. Indicates the vehicle's sideslip angle; Indicates the overall vehicle weight; This represents the yaw moment of inertia of a vehicle.
[0049] Assuming steady-state conditions, , The relationship between the rear wheel steering angle, front wheel steering angle, vehicle speed, and yaw rate is shown below:
[0050] (3)
[0051] (4)
[0052] in, This indicates the wheelbase of the vehicle.
[0053] The current front wheel steering angle of the vehicle will be collected. Speed and the vehicle's current yaw rate Input formulas (3) and (4) to calculate the rear wheel steering angle. The current rear wheel steering angle of the vehicle, where the front wheel steering angle is... It is controlled based on the steering wheel angle of the vehicle, and is directly proportional to the steering wheel angle, with the front wheel steering being the same as the steering wheel steering.
[0054] (23) High-speed driving scenario: Based on stability control, the rear wheel steering angle and steering are controlled to be in the same direction as the front wheel steering;
[0055] The current front wheel steering angle of the vehicle will be collected. Speed and the vehicle's current yaw rate Input formulas (3) and (4) to calculate the rear wheel steering angle. As the current rear wheel steering angle of the vehicle, it controls the rear wheel steering to be in the same direction as the front wheel steering.
[0056] In this embodiment of the invention, after reaching the characteristic speed, the rear wheel steering remains consistent with the front wheel steering. Below the characteristic speed, the rear wheel steering may not be consistent with the front wheel steering. When the vehicle is stable... When the vehicle reaches its characteristic speed, the rear wheels may adjust their steering, resulting in a change in the rear wheel steering angle at the characteristic speed. Characteristic vehicle speed At vehicle speed Once the characteristic speed is reached, the rear wheels are steered in the same direction as the front wheels to improve vehicle stability.
[0057] This invention adapts to different driving scenarios based on driving speed, and designs corresponding rear-wheel control strategies for different driving scenarios to dynamically balance the vehicle's steering flexibility and driving stability, thereby improving the vehicle's adaptability and driving comfort in different driving scenarios.
[0058] In this embodiment of the invention, a computer-readable storage medium is also provided. This storage medium can store a program suitable for processor execution. During program execution, the device containing the computer-readable storage medium controls the execution of the aforementioned rear-wheel steering control method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.
[0059] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.
[0060] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.
Claims
1. A rear wheel steering control method characterized by, The method is specifically as follows: (1) adapting to the corresponding driving scene based on the current vehicle speed of the vehicle; (2) adopting the corresponding rear wheel control strategy based on the current driving scene; Wherein, the driving scene includes: parking scene, urban low-speed commuting scene and high-speed driving scene.
2. The rear wheel steering control method of claim 1, wherein After entering the parking scene, the rear wheel steering angle is determined based on the steering wheel angle, the rear wheel steering is controlled to be opposite to the front wheel steering, and the rear wheel steering angle is linearly positively correlated with the steering wheel angle.
3. The rear wheel steering control method of claim 1, wherein After entering the urban low-speed commuting scene, when the vehicle speed is greater than or equal to the corresponding side-slip critical speed, the rear wheel steering and the rear wheel steering angle are controlled based on stability; when the vehicle speed is less than the corresponding side-slip critical speed, the rear wheel steering and the rear wheel steering angle are controlled based on flexibility.
4. The rear wheel steering control method according to claim 3, characterized by, The current working condition is determined based on the current steering wheel angle and the rear wheel steering angle, and the vehicle speed corresponding to the maximum yaw angular velocity in the current working condition is taken as the side-slip critical speed in the current working condition.
5. The rear wheel steering control method according to claim 4, characterized by, When the current vehicle speed is less than the side-slip critical speed in the current working condition, the rear wheel steering angle is determined based on the target yaw angular velocity, the current steering wheel angle and the vehicle speed, and the rear wheel steering is controlled to be opposite to the front wheel steering, wherein the target yaw angular velocity is less than the maximum yaw angular velocity corresponding to the working condition.
6. The rear wheel steering control method of claim 4, wherein When the current vehicle speed is greater than or equal to the side-slip critical speed in the current working condition, the current rear wheel steering angle is calculated based on the vehicle dynamics model under the steady-state condition, and the rear wheel steering is controlled to be the same as the front wheel steering.
7. The rear wheel steering control method of claim 1, wherein After entering the high-speed driving scene, the rear wheel steering angle is calculated based on the vehicle dynamics model under the steady-state condition, and the rear wheel steering is controlled to be the same as the front wheel steering.
8. The rear wheel steering control method of claim 7, characterized by Wherein, When the current vehicle speed is greater than or equal to the characteristic vehicle speed, the high-speed driving scene is entered, wherein the characteristic vehicle speed The calculation formula is as follows: ； wherein, denotes the wheelbase of the vehicle, , denote the front wheel cornering power, the rear wheel cornering power of the vehicle, respectively; , denote the distance of the center of mass to the front axle, the center of mass to the rear axle of the vehicle, respectively; denotes the total vehicle mass.
9. The rear wheel steering control method according to claim 6 or 7, characterized by, The vehicle dynamics model under the steady-state condition is specifically as follows: ； ； wherein, denotes the wheelbase of the vehicle, , denote the front wheel steering angle, the rear wheel steering angle of the vehicle, respectively; , denote the front wheel cornering stiffness, the rear wheel cornering stiffness of the vehicle, respectively; denotes the longitudinal vehicle speed; denotes the yaw angle of the vehicle; , denote the distance of the center of mass to the front axle, the center of mass to the rear axle of the vehicle, respectively; denotes the total vehicle mass.
10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to realize the rear wheel steering control method in any one of claims 1 to 9.