Vehicle steering control method, vehicle and storage medium

Abstract

The invention relates to a vehicle steering control method, a vehicle and a storage medium, and relates to the technical field of vehicles, the vehicle is provided with a first steering system, the first steering system does not comprise a steering motor, and a driving motor in the first steering system does not directly enable wheels to rotate. Therefore, driving torques in opposite directions are applied to the driving motors corresponding to the front wheels, the front axle yawing torques are loaded on the two front wheels, resistance and friction force are overcome through the front axle yawing torques, and in order to prevent a vehicle body from moving due to the fact that the front axle yawing torques are loaded on the front wheels, the two rear wheels are controlled before the front wheels are controlled, so that the vehicle is stopped; therefore, the vehicle can realize in-situ rotation of the wheels based on differential control of the four motors in a static state.

Description

Technical Field

[0001] This disclosure relates to the field of automotive technology, and more specifically, to a vehicle steering control method, a vehicle, and a storage medium. Background Technology

[0002] With the continuous advancement of automotive technology, the steering system, as a core component of vehicle control, has evolved from mechanical hydraulic power steering to fully electronic control. Currently, vehicle steering technologies mainly include mechanical hydraulic power steering (HPS), electro-hydraulic power steering (EHPS), electric power steering (EPS), steer-by-wire (SBW), and four-wheel steering (4WS), each with its unique advantages and limitations.

[0003] From a technological development perspective, electric power steering (EPS) is gradually becoming mainstream due to its high efficiency, energy saving, and ease of integration. EPS directly drives the steering column or rack via an electric motor, providing appropriate assistance based on vehicle speed and steering angle, significantly improving driving comfort and safety. The emergence of steer-by-wire technology marks a step towards fully electronic and intelligent steering systems. Steer-by-wire eliminates traditional mechanical connections, using electronic signals for steering control, further improving response speed and handling precision. However, its high cost and reliability issues still limit large-scale application, especially the redundant design of steer-by-wire systems; redundant hardware without heterogeneous design poses a safety risk of common-cause failure. Four-wheel drive differential steering technology achieves steering by simultaneously controlling the drive torque of the front or rear wheels, significantly improving vehicle handling stability and steering agility, especially at high speeds and when parking. However, four-wheel drive differential steering is achieved by rotating the left and right drive wheels at different speeds. When stationary, it cannot generate effective steering torque, thus making it impossible to control the front wheels while the vehicle is stationary. Summary of the Invention

[0004] The purpose of this disclosure is to provide a vehicle steering control method, a vehicle, and a storage medium to solve the problem that four-wheel drive differential steering technology cannot steer when the vehicle is stationary.

[0005] To achieve the above objectives, a first aspect of this disclosure provides a vehicle steering control method, wherein the vehicle is equipped with a first steering system, the first steering system excluding a steering motor, the method comprising: In response to the vehicle entering the stationary steering mode, the vehicle's steering wheel steering information, front wheel steering angle information, and rear wheel speed information are acquired, wherein the first steering system is used for steering in the stationary steering mode; Based on the speed deviation between the actual speed of the rear wheel and the target speed determined by the rear wheel speed information, a driving torque is applied to the drive motor corresponding to the rear wheel to keep the rear wheel stationary. When the rear wheels are stationary, based on the front wheel steering deviation determined by the steering wheel information and the front wheel angle information, drive torques in opposite directions are applied to the drive motors corresponding to the two front wheels to control the vehicle to turn in place according to the steering wheel information.

[0006] Optionally, before acquiring the vehicle's steering wheel steering information, front wheel steering angle information, and rear wheel speed information in response to the vehicle entering a stationary steering mode, the method further includes: The vehicle speed information is obtained, and when it is determined that the vehicle is stationary based on the speed information, the vehicle is prompted to enter the stationary turning mode.

[0007] Optionally, the vehicle is further equipped with a second steering system, the second steering system including a steering motor, and the acquisition of vehicle speed information includes: In response to the detection of a failure in the second steering system, the vehicle speed information is obtained.

[0008] Optionally, applying driving torque to the drive motor corresponding to the rear wheel based on the speed deviation between the actual rear wheel speed determined by the rear wheel speed information and the target speed includes: Determine the actual speed of the rear wheels based on the rear wheel speed information; Based on the difference between the target speed and the actual speed of the rear wheel, PID calculation is performed to obtain the control quantity of the drive motor corresponding to the rear wheel; Based on the control quantity, a driving torque is applied to the drive motor corresponding to the rear wheel.

[0009] Optionally, applying opposite driving torques to the drive motors corresponding to the two front wheels based on the front wheel steering deviation determined by the steering wheel steering information and the front wheel angle information includes: The actual front wheel angle is determined based on the front wheel angle information, and the target wheel angle is determined based on the steering wheel steering information. Based on the difference between the target wheel angle and the actual front wheel angle, PID calculation is performed to obtain the front axle yaw torque control quantity. The front axle yaw torque control amount is evenly distributed to obtain the wheel end torque control amount of each of the two front wheels; A forward-directed driving torque of the same magnitude as the wheel-end torque control amount is applied to the drive motor corresponding to the front wheel closest to the steering direction, and a backward-directed driving torque of the same magnitude as the wheel-end torque control amount is applied to the drive motor corresponding to the front wheel furthest from the steering direction.

[0010] Optionally, determining that the rear wheel is stationary includes: In response to receiving a valid control status flag, the current vehicle speed is detected. If the valid control status flag indicates that the rear wheels are stationary and the vehicle is determined to be stationary based on its current speed, then the rear wheels are determined to be stationary.

[0011] Optionally, after applying driving torques in opposite directions to the drive motors corresponding to the two front wheels, the method further includes: The drive torque of the drive motor corresponding to the front wheel is transmitted through the guide mechanism, so that the front wheel moves according to the guide motion trajectory. The guide mechanism includes a suspension linkage motion mechanism and / or a chassis steering trapezoidal mechanism. The guide mechanism is used to limit the motion trajectory of the front wheel turning angle.

[0012] Optionally, the vehicle includes a position sensor, which is mounted on the guide mechanism and outputs the position information of the guide mechanism; The acquisition of the vehicle's front wheel steering angle information includes: Obtain the position information of the guide mechanism, wherein the position information indicates the displacement of the guide mechanism; Based on the mapping relationship between the displacement of the guide mechanism and the wheel rotation angle, the front wheel rotation angle information of the vehicle is obtained.

[0013] A second aspect of this disclosure provides a vehicle equipped with a first steering system, the first steering system not including a steering motor, the vehicle comprising: A steering wheel angle sensor is used to acquire the steering wheel angle information; An angle sensor is used to acquire the front wheel angle information; A brake controller is used to acquire the rear wheel speed information; Motor controller, used to control the drive motor; A vehicle controller for performing the steps of the method described in any one of the first aspects.

[0014] A third aspect of this disclosure provides a vehicle steering control device, the device comprising: The acquisition module is configured to acquire the vehicle's steering wheel steering information, front wheel angle information, and rear wheel speed information in response to the vehicle entering the stationary steering mode. In the stationary steering mode, the first steering system is used for steering. The rear wheel control module is configured to apply drive torque to the drive motor corresponding to the rear wheel based on the speed deviation between the actual speed of the rear wheel determined by the rear wheel speed information and the target speed, so as to keep the rear wheel stationary. The front wheel control module is configured to apply opposite driving torques to the drive motors corresponding to the two front wheels based on the front wheel steering deviation determined by the steering wheel steering information and the front wheel steering angle information, when the rear wheels are stationary, so as to control the vehicle to turn in place according to the steering wheel steering information.

[0015] A fourth aspect of this disclosure provides an electronic device, comprising: A memory on which computer programs are stored; A processor for executing the computer program in the memory to implement the steps of the method of any one of the first aspects.

[0016] The fifth aspect of this disclosure provides a non-transitory computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the method described in any of the first aspects.

[0017] A sixth aspect of this disclosure provides a computer program product including a computer program that, when executed by a processor, implements the steps of the method described in any of the first aspects.

[0018] Through the above technical solution, in response to the vehicle entering the stationary steering mode, the first steering system first acquires the vehicle's steering wheel information, front wheel angle information, and rear wheel speed information. Based on the speed deviation between the actual rear wheel speed and the target speed determined by the rear wheel speed information, a driving torque is applied to the drive motors corresponding to the rear wheels to keep the rear wheels stationary. With the rear wheels stationary, based on the front wheel steering deviation determined by the steering wheel information and the front wheel angle information, opposite driving torques are applied to the drive motors corresponding to the two front wheels to control the vehicle to perform stationary steering according to the steering wheel information. The first steering system does not include a steering motor, and the drive motors do not directly change the wheel rotation direction. Therefore, by applying opposite driving torques to the drive motors corresponding to the front wheels, the two front wheels are loaded with front axle yaw torque. This front axle yaw torque overcomes resistance and friction. To prevent the front wheels from moving due to the front axle yaw torque, the two rear wheels are controlled to keep the vehicle stationary, allowing the vehicle to achieve stationary wheel rotation in a stationary state based on differentiated control of the four motors.

[0019] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a vehicle steering control method provided according to an embodiment of the present disclosure.

[0021] Figure 2 This is a flowchart of a vehicle entering a stationary turning mode according to an embodiment of the present disclosure.

[0022] Figure 3 This is a flowchart of an embodiment of the present disclosure for performing rear wheel control.

[0023] Figure 4 This is a flowchart of front wheel control according to an embodiment of the present disclosure.

[0024] Figure 5 This is a schematic diagram of the hardware structure of a vehicle provided in an embodiment of this disclosure.

[0025] Figure 6 This is a structural block diagram of a vehicle network architecture communication provided in an embodiment of this disclosure.

[0026] Figure 7 This is a schematic diagram of a vehicle steering control principle provided in an embodiment of this disclosure.

[0027] Figure 8 This is a schematic block diagram of a vehicle steering control device provided in an embodiment of this disclosure.

[0028] Reference numerals: 1. Front left motor; 2. Front right motor; 3. Rear left motor; 4. Rear right motor; 5. Motor drive transmission mechanism; 6. Suspension guide mechanism; 7. Steering guide mechanism; 8. Steering mechanism end angle sensor; 9. Steering wheel end angle sensor; 10. Front left tire; 11. Front right tire; 12. Rear left tire; 13. Rear left tire; 14. Steering wheel; 15. Subframe; 16. Body; 17. Front left wheel speed sensor; 18. Front right wheel speed sensor; 19. Rear left wheel speed sensor; 20. Rear right wheel speed sensor; 21. Steering gear. Detailed Implementation

[0029] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0030] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0031] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0032] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0033] Steering systems are evolving towards electrification, intelligence, connectivity, and integration. Electric power steering will continue to dominate the market, while steer-by-wire and four-wheel drive differential steering are expected to see wider application in the future due to technological breakthroughs and cost reductions. The vehicle steering method, apparatus, storage medium, program product, and vehicle executing the method provided in this disclosure solve the problem that current four-wheel drive differential steering technology cannot steer while the vehicle is stationary by controlling the vehicle's four motors, enabling steering even when the steer-by-wire system fails.

[0034] Figure 1 This is a flowchart of a vehicle steering control method according to an embodiment of this disclosure. The vehicle in this method is equipped with a first steering system, which does not include a steering motor. Exemplarily, the first steering system is the four-wheel drive differential steering system mentioned above. Figure 1 As shown, the method includes steps S11 to S13.

[0035] Step S11: In response to the vehicle entering the stationary steering mode, obtain the vehicle's steering wheel steering information, front wheel angle information and rear wheel speed information, wherein the first steering system is used for steering in the stationary steering mode.

[0036] The stationary steering mode is a steering mode provided in the embodiments of this disclosure for vehicles. It refers to a mode in which the vehicle is steered using its first steering system while stationary. The first steering system does not include a steering motor, and the motor that drives the vehicle to rotate in the first steering system is a linear drive motor (hereinafter referred to as the drive motor).

[0037] Steering information can be obtained by detecting the driver's expected steering angle using the steering wheel angle sensor, which represents the vehicle's target steering direction.

[0038] Front wheel steering angle information can be detected by front wheel angle sensors. In some embodiments, the front wheels of the vehicle do not need to be equipped with angle sensors. Instead, a steering angle sensor is installed on the guide mechanism end of the vehicle's built-in guide mechanism, and the front wheel steering angle information is calculated using the proportional relationship between the front wheel rotation angle and the displacement of the guide mechanism. This saves the hardware cost of installing additional sensors on the vehicle.

[0039] Rear wheel speed information is obtained by detecting wheel speed signals through rear wheel speed sensors. It's understood that the vehicle also includes front wheel speed sensors to detect the front wheel speed signals. Rear wheel speed information includes left and right rear wheel speed information, where left and right are relative to the front of the vehicle; the wheel on the left side of the front is the left wheel, and the wheel on the right side is the right wheel.

[0040] In some embodiments, prior to step S11, the method provided in this disclosure is as follows: Figure 2 As shown, it includes steps S21 to S22.

[0041] Step S21: Obtain vehicle speed information.

[0042] Step S22: When the vehicle is determined to be stationary based on the vehicle speed information, prompt the vehicle to enter the stationary turning mode.

[0043] The vehicle speed information can be obtained by converting wheel speed signals detected by wheel speed sensors, including left front wheel speed sensors, right front wheel speed sensors, left rear wheel speed sensors, and right rear wheel speed sensors. The vehicle speed information can be a vehicle speed signal or a speed value converted from a vehicle speed signal. When the vehicle speed information indicates that the current vehicle speed is equal to or approximately equal to zero, and the vehicle is determined to be stationary, the user can be notified via the vehicle's infotainment system or voice prompts that the vehicle has entered stationary steering mode. Specifically, and not limited to, the vehicle's infotainment system display can show "Currently in stationary steering mode with four motors controlling the wheels." It is understood that when the vehicle exits stationary steering mode, relevant information can also be displayed to indicate to the user that the mode has been exited; this disclosure will not elaborate on this further.

[0044] It is worth mentioning that the first steering system for controlling wheel rotation via four motors provided in this embodiment can enter both the stationary steering mode and the driving steering mode, as mentioned above. The difference between the stationary steering mode and the driving steering mode is whether the vehicle is steering while stationary or in motion. The driving steering mode is implemented as follows: in response to the vehicle entering the driving steering mode, the vehicle's steering wheel information and front wheel angle information are acquired; based on the front wheel steering deviation determined by the steering wheel information and the front wheel angle information, opposite driving torques are applied to the drive motors corresponding to the two front wheels to control the vehicle to steer according to the steering wheel information. This steering is performed while the vehicle is in motion. In some embodiments, the switching condition between the stationary steering mode and the driving steering mode is whether the vehicle is currently stationary, such as by detecting whether the vehicle speed is zero to determine which steering mode to switch to.

[0045] The above description addresses the scenario where the vehicle is equipped with a first steering system. In practical applications, the vehicle can also be equipped with a second steering system, which can be a steer-by-wire system and includes a steering motor. It is understood that the first and second steering systems drive the wheels differently. The second steering system includes a steering motor and a rack and pinion mechanism coupled to the wheels. The steering torque applied to the wheels by the second steering system originates from the rack force output by the rack and pinion mechanism, while the steering torque applied to the wheels by the first steering system is actually the front axle yaw torque generated by a pair of oppositely directed driving torques acting on the two front wheels. In embodiments where the vehicle is equipped with at least two steering systems, the vehicle uses the second steering system for normal steering, and when a failure of the first steering system is detected, the wheels are steered using the first steering system. Therefore, step S21 includes: in response to detecting a failure of the second steering system, acquiring the vehicle's speed information.

[0046] In stationary steering mode, the operations of controlling the rear wheels to stay stationary and controlling the front wheels to rotate are performed sequentially, as detailed in steps S12 and S13.

[0047] Step S12: Based on the speed deviation between the actual speed of the rear wheel and the target speed determined by the rear wheel speed information, apply driving torque to the drive motor corresponding to the rear wheel to make the rear wheel stand still.

[0048] In stationary steering mode, to prevent the vehicle from veering due to the driving torque applied to the front wheels, differentiated control is applied to the drive motors of the front and rear wheels. Step S12 executes drive control on the rear wheel drive motor to keep the rear wheels stationary. The magnitude and direction of the driving torque applied to the rear wheels are calculated by reducing the speed deviation between the actual speed of the rear wheels and the target speed. In other words, the purpose of the magnitude and direction of the torque applied to the rear wheels is to make the actual speed of the rear wheels reach the target speed. In this step, the target speed is the speed at which the rear wheels come to a stop, such as a target speed of 0, or a target speed close to 0, such as a target speed of 1 km / h, 2 km / h, 5 km / h, etc. In this embodiment, the method for determining the driving torque of the rear wheel drive motor based on the speed deviation can be PID (Proportional-Integral-Derivative) control, fuzzy control, machine learning, etc., and this disclosure does not limit this.

[0049] By controlling the two rear wheels at zero speed and utilizing the adhesion between the wheels and the ground to keep the vehicle and body relatively stationary, the vehicle (or body) avoids relative ground movement when the position of the front wheels is controlled for steering.

[0050] In some embodiments, step S12 described above includes, for example: Figure 3 Steps S31 to S33 are shown.

[0051] Step S31: Determine the actual speed of the rear wheels based on the rear wheel speed information.

[0052] The vehicle collects wheel speed signals via wheel speed sensors installed on the left and / or right rear wheels. The rear wheel speed information can include the left rear wheel speed signal and / or the right rear wheel speed signal. The vehicle converts the wheel speed signals into actual speeds, such as converting the left rear wheel speed signal into the actual speed of the left rear wheel, and the right rear wheel speed signal into the actual speed of the right rear wheel.

[0053] Step S32: Based on the difference between the target speed and the actual speed of the rear wheels, perform PID calculation to obtain the control quantity of the drive motor corresponding to the rear wheels.

[0054] The target speed is a preset value of the vehicle system, such as 0 km / h. The difference between the target speed and the actual speeds of the left and right rear wheels is calculated to obtain the speed deviations for each wheel. These two speed deviations are input as e(t) to the PID controller. The PID controller then obtains the control quantity u(t) according to the formula u(t) = Kp × e(t) + Ki × ∫e(t)dt + Kd × de(t) / dt. Here, Kp is used for rapid response to deviation, Ki is used to eliminate steady-state error, and Kd is used to suppress overshoot.

[0055] Step S33: Based on the control quantity, apply the drive torque to the drive motor corresponding to the rear wheel.

[0056] The vehicle controller sends the control signals of the drive motors corresponding to the left and right rear wheels to the left and right rear motor controllers via the CAN bus. The motor controllers then control the drive motors to output positive or negative torque to counteract the vehicle's movement and keep the actual speed of the rear wheels near zero.

[0057] The technical solutions provided in steps S31 to S33 achieve precise vehicle stationary control by dynamically adjusting the drive torque of the rear wheels through PID closed-loop control based on wheel speed deviation.

[0058] In some embodiments, determining that the rear wheels have reached a valid stationary state is a prerequisite for executing step S13. The specific determination process is as follows: The wheel detects the valid control status flag bit issued by the rear wheel stationary control module, which is represented by a Boolean value; TRUE is given when the rear wheels are stationary. The vehicle obtains the current vehicle speed calculated from the wheel speed information through the vehicle controller. If the valid control status flag bit indicates that the rear wheels are stationary and the vehicle is determined to be stationary based on the current vehicle speed, it is determined that the rear wheels have truly reached a valid stationary state.

[0059] This embodiment effectively prevents errors in determining the stationary state due to the failure of a single sensor, thus improving system stability.

[0060] Step S13: When the rear wheels are stationary, based on the front wheel steering deviation determined by the steering wheel information and the front wheel angle information, drive torques in opposite directions are applied to the drive motors corresponding to the two front wheels to control the vehicle to turn in place according to the steering wheel information.

[0061] In this step, the method for determining the drive torque of the front wheel drive motor based on the front wheel steering deviation can be the same as that for the rear wheels, such as using PID control, fuzzy control, or machine learning for both front and rear wheels. Alternatively, different control methods can be used for the front and rear wheels, such as using fuzzy control for the front wheels and PID control for the rear wheels.

[0062] In some embodiments, step S13 includes, for example: Figure 4 Steps S41 to S44 are shown.

[0063] Step S41: Determine the actual front wheel angle based on the front wheel angle information, and determine the target wheel angle based on the steering wheel information.

[0064] Step S42: Based on the difference between the target wheel angle and the actual front wheel angle, perform PID calculation to obtain the front axle yaw torque control quantity.

[0065] Step S43: Distribute the front axle yaw torque control amount equally to obtain the wheel end torque control amount of each of the two front wheels.

[0066] Step S44: Apply a forward-directed driving torque of the magnitude of the wheel end torque control amount to the drive motor corresponding to the front wheel closer to the steering direction, and apply a backward-directed driving torque of the magnitude of the wheel end torque control amount to the drive motor corresponding to the front wheel farther from the steering direction.

[0067] In this design, the front wheels furthest from the steering direction are referred to as the outer wheels, and the front wheels closest to the steering direction are referred to as the inner wheels. The reason for applying torque to the inner wheels backward and the outer wheels forward is that the desired wheel steering direction needs to be consistent with the direction of the applied front axle yaw torque. The target front axle yaw torque control amount is evenly distributed, so that the driving torque of the inner wheels is -0.5 × the front axle yaw torque control amount, and the driving torque of the outer wheels is +0.5 × the front axle yaw torque control amount. Here, the sign indicates the direction is backward, and the positive sign indicates the direction is forward. The vehicle controller sends the driving torque of the two front wheels to the corresponding motor controllers of the two front wheels, so that the motor controllers drive the corresponding front wheel motors to output torques of equal magnitude but opposite direction, generating a torque couple that causes the wheels to deflect.

[0068] In some embodiments, after the drive motors of the two front wheels output drive torques in opposite directions, the physical deflection of the wheels is achieved through the vehicle's inherent mechanical structure. Exemplarily, the opposite drive torques act on the left and right front wheels, and the friction between the tires and the ground is converted into a force attempting to deflect the wheels, which is transmitted to the vehicle's guiding mechanism. The guiding mechanism provided in this disclosure includes: The suspension linkage motion mechanism defines the kingpin axis around which the wheel rotates, constraining the wheel to rotate only around this axis; Chassis steering trapezoidal mechanism: including steering tie rod and left and right steering knuckle arms, defines the mechanical steering angle of the left rear wheel in accordance with Ackermann geometry.

[0069] When the force generated by the driving torque of the front wheel acts on the guiding mechanism, the guiding mechanism uses its constraint function to convert the wheel's offset tendency into a preset guiding motion trajectory, so as to achieve controllable wheel steering.

[0070] This embodiment utilizes the inherent geometric constraints of the suspension linkage and steering trapezoidal mechanism to achieve physical wheel deflection without the need for additional hardware, effectively reducing costs and implementation difficulty.

[0071] In some embodiments, front wheel steering angle information is obtained by reusing existing sensors. For example, a position sensor, such as a steering angle sensor, is mounted on the vehicle's steering mechanism, located on the output shaft of the steering gear. When the steering wheel or wheels turn, the steering gear input shaft rotates accordingly. The sensor detects its rotation angle (i.e., the position information of the steering mechanism) in real time and outputs an electrical signal to the steering controller. The steering controller stores a mapping relationship between the position information of the steering mechanism and the actual steering angle of the front wheels. Therefore, based on the received electrical signal and this mapping relationship, the front wheel steering angle information can be obtained and sent to the vehicle controller via the CAN bus. This embodiment eliminates the need for additional sensors in the first steering system, reducing cost and complexity by directly reusing the existing hardware of the wheels.

[0072] Through the above technical solution, in response to the vehicle entering the stationary steering mode, the vehicle is controlled using the first steering system. Since the first steering system uses a drive motor to achieve vehicle steering, the drive motor does not directly cause the wheels to turn. Therefore, by applying a driving torque in the opposite direction to the drive motors corresponding to the front wheels, the two front wheels are loaded with front axle yaw torque. This front axle yaw torque overcomes the steering resistance within the chassis system, the vehicle's self-centering torque, and the friction between the tires and the ground, enabling the left and right front wheels to rotate to the target position. It can be understood that in stationary steering mode, to prevent the vehicle body from moving due to the front axle yaw torque applied to the front wheels, the two rear wheels are controlled to keep the vehicle stationary, allowing the vehicle to achieve wheel rotation in a stationary state based on the differentiated control of the four motors.

[0073] The method provided in this disclosure can be applied to, for example... Figure 5 The vehicle with the hardware structure shown.

[0074] The vehicles include: The left front motor 1 and the right front motor 2 are equivalent to the drive motors that perform front wheel steering as described above. The left rear motor 3 and the right rear motor 4 are equivalent to the drive motors mentioned above that enable the rear wheels to remain stationary; the vehicle also includes a motor controller for controlling the aforementioned drive motors.

[0075] The motor-driven transmission mechanism 5 is equivalent to a transmission system that transmits motor torque to the wheels, such as a drive actuator in the second drive system. Suspension guiding mechanism 6 and steering guiding mechanism 7 are equivalent to the guiding mechanisms mentioned above. The two work together to overcome the wheel rotation resistance torque after the front axle yaw torque is overcome, and then guide the direction of wheel movement. The guide mechanism end angle sensor 8 is used to detect the actual position of the wheel rotation. In one embodiment, the vehicle includes an angle sensor to obtain front wheel angle information. The steering wheel angle sensor 9 (or steering wheel angle sensor) is used to detect the driver's expected steering angle. The left front tire is 10mm; it is the inner wheel when turning left and the outer wheel when turning right. The right front tire is 11mm; it is the outer wheel when turning left and the inner wheel when turning right. Left rear tire 12, right rear tire 13; Steering wheel 14; The subframe 15 secures one end of the steering guide mechanism and the suspension guide mechanism, and is rigidly connected to the vehicle body. The vehicle body 16 utilizes the rear axle tires to maintain ground contact and keep the vehicle body stationary, while the vehicle body provides yaw torque support to the front axle. The left front wheel speed sensor 17, the right front wheel speed sensor 18, the left rear wheel speed sensor 19, and the right rear wheel speed sensor 20 are used to monitor wheel speed signals, wherein the rear wheel speed signal can be transmitted to the brake controller. Steering gear 21 is the actuator of the second steering system. In embodiments where the vehicle is not equipped with the second steering system, the vehicle may not include steering gear 21. The vehicle also includes a vehicle controller for performing the methods provided in the embodiments of this disclosure.

[0076] The vehicle provided in this embodiment has a network architecture communication as follows: Figure 6 As shown, it includes a high-speed CAN1 network, a high-speed CAN2 network, a high-speed CAN3 network, and a high-speed CAN4 network.

[0077] The vehicle controller includes a signal processing module, a steering fault management module, a drive steering mode selection module, and a stationary drive steering control module. The signal processing module receives wheel speed signals from the four wheel speed sensors processed by the brake controller, steering angle signals from the steering wheel angle sensor, actual steering position signals from the wheel guide mechanism angle sensor processed by the steering controller, fault status signals from the second steering system, actual torque signals from the four drive motors, and drive steering status signals from the high-speed CAN1 network, and identifies and outputs the validity of each signal.

[0078] The steering fault management module receives the fault status signal of the steering system for validity assessment and executes corresponding tasks according to the defined fault status and fault assessment rules. These tasks include: when the second steering system is functioning normally, the steering fault management module is responsible for monitoring and assessing steering faults; when the second steering system malfunctions but the drive steering feedback is normal, the drive steering mode selection module activates its operating mode; and when the second steering system malfunctions and the drive steering feedback is faulty, the module limits the vehicle speed or brings it to a complete stop according to the defined fault rules.

[0079] The drive steering mode selection module includes a driving steering module and a stationary steering module. When activated, the drive steering mode selection module receives a vehicle speed signal after validity assessment by the signal processing module and selects a mode according to the rules and conditions defined by the vehicle speed. When the vehicle speed > 0, it enters driving steering mode and activates the driving steering module; when the vehicle speed = 0, it enters stationary steering mode and activates the stationary steering module. The stationary steering module includes a rear wheel stationary control module and a front wheel position control module, used to execute steps S12 and S13 above, which will not be elaborated upon here.

[0080] The vehicle controller, via the high-speed CAN2 network, sends the wheel-end drive torque (inner steering wheel backward, outer steering wheel forward) to the left and right front motor controllers to control the motor output drive torque. The actual front axle yaw moment is obtained by controlling the motor output drive torque through the left and right front motor controllers. This actual front axle yaw moment overcomes resistance and drives the wheels to rotate. The resistance overcome by the wheel rotation includes internal resistance of the chassis guiding mechanisms (such as suspension guiding mechanisms and steering guiding mechanisms), self-centering resistance, and tire and ground friction.

[0081] In an embodiment where the vehicle is equipped with two steering systems, the guiding mechanism in the second steering system transmits the steering rack thrust and, after overcoming resistance, propels the wheel to move along a predetermined trajectory in cooperation with the suspension guiding mechanism; the guiding mechanism in the first steering system transmits the front axle yaw moment force at the wheel end and, after overcoming resistance, moves along the trajectory guided by the wheel.

[0082] In some embodiments, there are several ways to exit the stationary turning mode.

[0083] In the first case, the driving steering mode selection module is in the on state. When the vehicle speed is >0, the stationary steering mode is exited and the driving steering mode is entered. In the second case, the drive steering mode selection module is in the on state. When the fault state of the second steering system returns to normal, the stationary steering mode is exited and the normal steering control mode of the second steering system is entered. The steering fault management module is restored to the working state of steering fault monitoring and judgment. In the third case, the driving steering mode selection module is in the on state. When the steering system malfunctions or the driving steering state changes from normal to malfunction, the stationary steering mode is exited, and the steering fault management module limits the vehicle speed or stops it according to the defined fault rules. In the fourth case, the drive steering mode selection module is in the on state. After the vehicle is parked, the power is turned off (IG off), and the stationary drive steering function is normally deactivated.

[0084] refer to Figure 7 This is a schematic diagram of a vehicle steering control principle provided in an embodiment of this disclosure, such as... Figure 5 As shown, signal processing is performed first, as described in the previous section on the signal processing module. Then, the steering fault management module selects from three modes: The first mode utilizes the second steering system when both steering systems are functioning normally; the second mode limits or stops the vehicle when both the first and second steering systems fail; and the third mode selects the first steering system when the second steering system fails, determining whether to enter stationary steering mode or driving steering mode based on whether the current vehicle speed is greater than 0. In stationary steering mode, stationary drive steering is performed, meaning rear wheel stationary control is executed first, followed by front wheel position control. In driving steering mode, driving drive steering is performed directly, meaning front wheel position control is executed.

[0085] Based on the same technical concept, this disclosure also provides a vehicle steering control device, which can, as follows: Figure 8 As shown, it includes: The acquisition module 801 is configured to acquire the vehicle's steering wheel steering information, front wheel angle information, and rear wheel speed information in response to the vehicle entering the stationary steering mode. In the stationary steering mode, the vehicle uses the first steering system for steering.

[0086] The rear wheel control module 802 is configured to apply a driving torque to the drive motor corresponding to the rear wheel based on the speed deviation between the actual speed of the rear wheel determined by the rear wheel speed information and the target speed, so as to keep the rear wheel stationary.

[0087] The front wheel control module 803 is configured to apply opposite driving torques to the drive motors corresponding to the two front wheels based on the front wheel steering deviation determined by the steering wheel steering information and the front wheel steering angle information when the rear wheels are stationary, so as to control the vehicle to turn in place according to the steering wheel steering information.

[0088] Optionally, the acquisition module 801 is also configured to acquire vehicle speed information, and when it is determined that the vehicle is stationary based on the vehicle speed information, prompt the vehicle to enter the stationary turning mode.

[0089] Optionally, the acquisition module 801 is also configured to acquire vehicle speed information in response to detecting a failure of the second steering system.

[0090] Optionally, the rear wheel control module 802 is further configured to determine the actual speed of the rear wheel based on the rear wheel speed information; perform PID calculation based on the difference between the target speed and the actual speed of the rear wheel to obtain the control quantity of the drive motor corresponding to the rear wheel; and apply drive torque to the drive motor corresponding to the rear wheel based on the control quantity.

[0091] Optionally, the front wheel control module 803 is further configured to determine the actual front wheel angle based on the front wheel angle information and the target wheel angle based on the steering wheel information; perform PID calculation based on the difference between the target wheel angle and the actual front wheel angle to obtain the front axle yaw torque control quantity; distribute the front axle yaw torque control quantity evenly to obtain the wheel end torque control quantity for each of the two front wheels; apply a forward-directed driving torque equal to the wheel end torque control quantity to the drive motor corresponding to the front wheel closer to the steering direction, and apply a backward-directed driving torque equal to the wheel end torque control quantity to the drive motor corresponding to the front wheel farther from the steering direction.

[0092] Optionally, the front wheel control module 803 is further configured to detect the current vehicle speed in response to receiving a valid control status flag bit, and determine that the rear wheels are stationary if the valid control status flag bit indicates that the rear wheels are stationary and the vehicle is determined to be stationary based on the current vehicle speed.

[0093] Optionally, the vehicle also includes a mechanical transmission module configured to transmit the drive torque of the drive motor corresponding to the front wheel through a guide mechanism, so that the front wheel moves according to the guide motion trajectory. The guide mechanism includes a suspension linkage motion mechanism and / or a chassis steering trapezoidal mechanism, and the guide mechanism is used to limit the motion trajectory of the front wheel steering angle.

[0094] Optionally, the acquisition module 801 is further configured to acquire position information of the guide mechanism, the position information indicating the displacement of the guide mechanism; and acquire the front wheel angle information of the vehicle based on the mapping relationship between the displacement of the guide mechanism and the wheel angle.

[0095] Based on the same technical concept, embodiments of this disclosure also provide a computer program product, including a computer program that, when executed by a processor of an electronic device, implements the method shown in any embodiment of this disclosure.

[0096] Based on the same technical concept, embodiments of this disclosure also provide a computer-readable storage medium storing a computer program thereon, which, when executed, implements the method as shown in any embodiment of this disclosure. For example, the non-transitory computer-readable storage medium may be the aforementioned memory 732 including program instructions, which may be executed by the processor 722 of the electronic device 700 to complete the aforementioned vehicle steering control method.

[0097] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0098] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0099] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A vehicle steering control method, characterized in that, The vehicle is equipped with a first steering system, the first steering system not including a steering motor, and the method includes: In response to the vehicle entering the stationary steering mode, the vehicle's steering wheel steering information, front wheel steering angle information, and rear wheel speed information are acquired, wherein the first steering system is used for steering in the stationary steering mode; Based on the speed deviation between the actual speed of the rear wheel and the target speed determined by the rear wheel speed information, a driving torque is applied to the drive motor corresponding to the rear wheel to keep the rear wheel stationary. When the rear wheels are stationary, based on the front wheel steering deviation determined by the steering wheel information and the front wheel angle information, drive torques in opposite directions are applied to the drive motors corresponding to the two front wheels to control the vehicle to turn in place according to the steering wheel information.

2. The vehicle steering control method according to claim 1, characterized in that, Before acquiring the vehicle's steering wheel steering information, front wheel steering angle information, and rear wheel speed information in response to the vehicle entering a stationary steering mode, the method further includes: The vehicle speed information is obtained, and when it is determined that the vehicle is stationary based on the speed information, the vehicle is prompted to enter the stationary turning mode.

3. The vehicle steering control method according to claim 2, characterized in that, The vehicle is also equipped with a second steering system, which includes a steering motor. The acquisition of vehicle speed information includes: In response to the detection of a failure in the second steering system, the vehicle speed information is obtained.

4. The vehicle steering control method according to claim 1, characterized in that, The step of applying driving torque to the drive motor corresponding to the rear wheel based on the speed deviation between the actual speed of the rear wheel determined by the rear wheel speed information and the target speed includes: Determine the actual speed of the rear wheels based on the rear wheel speed information; Based on the difference between the target speed and the actual speed of the rear wheel, PID calculation is performed to obtain the control quantity of the drive motor corresponding to the rear wheel; Based on the control quantity, a driving torque is applied to the drive motor corresponding to the rear wheel.

5. The vehicle steering control method according to claim 1, characterized in that, The step of applying opposite driving torques to the drive motors corresponding to the two front wheels based on the front wheel steering deviation determined by the steering wheel steering information and the front wheel angle information includes: The actual front wheel angle is determined based on the front wheel angle information, and the target wheel angle is determined based on the steering wheel steering information. Based on the difference between the target wheel angle and the actual front wheel angle, PID calculation is performed to obtain the front axle yaw torque control quantity. The front axle yaw torque control amount is evenly distributed to obtain the wheel end torque control amount of each of the two front wheels; A forward-directed driving torque of the same magnitude as the wheel-end torque control amount is applied to the drive motor corresponding to the front wheel closest to the steering direction, and a backward-directed driving torque of the same magnitude as the wheel-end torque control amount is applied to the drive motor corresponding to the front wheel furthest from the steering direction.

6. The vehicle steering control method according to claim 1, characterized in that, Determining that the rear wheel is stationary includes: In response to receiving a valid control status flag, the current vehicle speed is detected. If the valid control status flag indicates that the rear wheels are stationary and the vehicle is determined to be stationary based on its current speed, then the rear wheels are determined to be stationary.

7. The vehicle steering control method according to claim 1 or 5, characterized in that, After applying driving torques in opposite directions to the drive motors corresponding to the two front wheels, the method further includes: The drive torque of the drive motor corresponding to the front wheel is transmitted through the guide mechanism, so that the front wheel moves according to the guide motion trajectory. The guide mechanism includes a suspension linkage motion mechanism and / or a chassis steering trapezoidal mechanism. The guide mechanism is used to limit the motion trajectory of the front wheel turning angle.

8. The vehicle steering control method according to claim 7, characterized in that, The vehicle includes a position sensor, which is mounted on the guide mechanism and outputs the position information of the guide mechanism. The steps for obtaining the front wheel steering angle information include: Obtain the position information of the guide mechanism, wherein the position information indicates the displacement of the guide mechanism; Based on the mapping relationship between the displacement of the guide mechanism and the wheel rotation angle, the front wheel rotation angle information of the vehicle is obtained.

9. A vehicle, characterized in that, The vehicles include: A steering wheel angle sensor is used to acquire the steering wheel angle information; An angle sensor is used to acquire the front wheel angle information; A brake controller is used to acquire the rear wheel speed information; Motor controller, used to control the drive motor; A vehicle controller for performing the vehicle steering control method as described in any one of claims 1 to 8.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the program instructions are executed by the processor, they implement the vehicle steering control method as described in any one of claims 1 to 8.

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