Vehicle steering control method and apparatus, system, vehicle, and storage medium

Abstract

A vehicle steering control method and apparatus, a system, a vehicle, and a storage medium. The method comprises: when a crab steering function is activated, controlling two rear wheels of the vehicle to steer in the same direction as front wheels, and performing differential torque control on the two rear wheels of the vehicle, so as to enable the vehicle to perform crab movement.

Description

Steering control method, device, system, vehicle and storage medium of vehicle

[0001] This application claims priority to Chinese Patent Application No. 202411049802.1, filed on July 31, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of vehicles, and in particular, to a steering control method, device, system, vehicle and storage medium of a vehicle. BACKGROUND

[0003] Traditional steering function is mainly achieved by controlling the front wheel steering angle through the driver operating the steering wheel. In the face of narrow space or complex environment, the turning radius of the aforementioned steering mode is large, which may cause the driver to be difficult to pass through the narrow curved zone or bypass the obstacles at one time. SUMMARY

[0004] The present disclosure provides a steering control method of a vehicle, a corresponding control device, a corresponding electric drive system, a corresponding vehicle and a corresponding computer-readable storage medium.

[0005] In a first aspect, a steering control method of a vehicle is provided, the method comprising:

[0006] When the crab function is activated, controlling the two rear wheels of the vehicle to steer in the same direction as the front wheel, and performing differential torque control on the two rear wheels of the vehicle to make the vehicle crab.

[0007] In some embodiments, the method further comprises:

[0008] Controlling the two rear wheels of the vehicle to steer to a target steering angle, the target steering angle being adapted to be set to any value between zero degrees and a steering threshold value.

[0009] In some embodiments, the target steering angle is the steering threshold value of the rear wheels.

[0010] In some embodiments, the performing differential torque control on the two rear wheels of the vehicle comprises:

[0011] Performing differential torque control on the two rear wheels of the vehicle according to the difference between the front wheel steering angle and the rear wheel steering angle, and the rear axle differential torque, to make the vehicle crab.

[0012] In some embodiments, the performing differential torque control on the two rear wheels of the vehicle according to the difference between the front wheel steering angle and the rear wheel steering angle, and the rear axle differential torque, to make the vehicle crab, comprises:

[0013] determining a rear axle demand torque according to a difference between the front wheel steering angle and the rear wheel steering angle;

[0014] controlling the two rear wheels of the vehicle in differential torque according to the rear axle demand torque and the rear axle differential torque, so as to crab the vehicle.

[0015] In some embodiments, the front wheel steering angle is in positive proportion to the steering wheel angle.

[0016] In some embodiments, the rear axle differential torque comprises a rear axle basic differential torque, which is determined according to the steering wheel angle and the steering wheel torque according to a preset corresponding relationship.

[0017] In some embodiments, the rear axle differential torque further comprises a correction coefficient, and the rear axle differential torque = the rear axle basic differential torque x the correction coefficient; the correction coefficient comprises at least one of a brake attenuation coefficient, a rear wheel torque coefficient or a slope attenuation coefficient, and the differential torque of the two rear wheels has different numerical signs.

[0018] In some embodiments, the rear axle differential torque further comprises a correction coefficient and a direction indication value, and the rear axle differential torque = the direction indication value x the rear axle basic differential torque x the correction coefficient; the correction coefficient comprises at least one of a brake attenuation coefficient, a rear wheel torque coefficient or a slope attenuation coefficient, the direction indication value is positive when the steering direction of the vehicle is left, and the direction indication value is negative when the steering direction of the vehicle is right.

[0019] In some embodiments, the brake attenuation coefficient is in negative correlation with the brake depth.

[0020] In some embodiments, the slope attenuation coefficient is in negative correlation with the slope.

[0021] In some embodiments, the controlling the two rear wheels of the vehicle in differential torque so as to crab the vehicle comprises:

[0022] if it is determined that the vehicle satisfies a preset activation condition based on vehicle driving information and vehicle environment information, activating the crab function and controlling the two rear wheels of the vehicle in differential torque so as to crab the vehicle;

[0023] if it is determined that the vehicle does not satisfy the preset activation condition based on the vehicle driving information and the vehicle environment information, not activating the crab function.

[0024] In some embodiments, the vehicle driving information comprises front wheel steering angle information, gear information and brake depth information, and the vehicle environment information comprises slope information.

[0025] The preset activation condition comprises: the front wheel steering angle information does not exceed a preset angle threshold, the slope information does not exceed a preset slope threshold, the brake depth information does not exceed a preset depth threshold, and the gear information satisfies preset driving information, wherein the preset driving information comprises preset forward driving information and preset reverse driving information.

[0026] In some embodiments, the method further comprises:

[0027] Performing zero-crossing torque smoothing control on the vehicle according to the current vehicle speed and the road adhesion coefficient of the vehicle.

[0028] In some embodiments, the performing zero-crossing torque smoothing control on the vehicle according to the current vehicle speed and the road adhesion coefficient of the vehicle comprises:

[0029] Determining a wheel end actual torque according to the current vehicle speed and the road adhesion coefficient of the vehicle;

[0030] Controlling a torque variation amplitude when a crab function target torque is output based on a torque range of the wheel end actual torque.

[0031] In some embodiments, the method further comprises:

[0032] Limiting the crab function target torque according to the road adhesion coefficient.

[0033] In some embodiments, the limiting the crab function target torque according to the road adhesion coefficient comprises:

[0034] If it is determined that the rear wheel slips based on the road adhesion coefficient, limiting the rear wheel end target torque based on a rear wheel drive motor torque;

[0035] If it is determined that the rear wheel does not slip based on the road adhesion coefficient, limiting the rear wheel end target torque based on the rear wheel drive motor torque and a rear wheel torque limit.

[0036] In some embodiments, the method further comprises:

[0037] Revising a current driving trajectory of the vehicle according to a yaw rate.

[0038] In some embodiments, the method further comprises:

[0039] Outputting a display of the revised driving trajectory to assist a driver.

[0040] In a second aspect, a control device is provided, comprising a controller assembly, a memory, and a computer program stored on the memory, which, when executed by the controller assembly, implements any of the vehicle steering control methods.

[0041] In some embodiments, the controller assembly comprises a vehicle controller, a vehicle motion controller and a motor control unit.

[0042] In some embodiments, the vehicle controller performs crabbing function failure determination and sends a crabbing function failure instruction to the vehicle motion controller; the vehicle motion controller performs crabbing function failure determination again based on the crabbing function failure instruction.

[0043] In some embodiments, the vehicle motion controller sends a crabbing function activation instruction to the vehicle controller, and the vehicle controller performs crabbing function activation determination based on the crabbing function activation instruction.

[0044] In some embodiments, the controller assembly further comprises a display for displaying the driving trajectory of the vehicle during crabbing motion in response to a crabbing function start instruction.

[0045] In a third aspect, an electric drive system is provided, comprising:

[0046] a motor at the front end for outputting torque to the two front wheels of the vehicle, two motors at the rear end for outputting torque to the two rear wheels of the vehicle, and the control device of any one of the preceding items.

[0047] In a fourth aspect, a vehicle is provided, comprising: the control device of any one of the preceding items; or the electric drive system of any one of the preceding items.

[0048] In a fifth aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by a processor to implement the steering control method of the vehicle of any one of the preceding items.

[0049] In some embodiments of the present disclosure, when the crabbing function is activated, the two rear wheels of the vehicle can be controlled to steer in the same direction as the front wheels, and differential torque control can be performed on the two rear wheels of the vehicle to compensate for the difference between the front axle steering angle and the rear axle steering angle based on the differential torque control, so that the vehicle crabbing motion is achieved, a larger angle of crabbing obstacle avoidance is achieved, and the turning radius of the vehicle is reduced, achieving the purpose of rapid turning or obstacle avoidance in urban narrow space. In some embodiments, the point-to-point oblique motion with almost no yaw can also be achieved by the intervention of the differential torque control on the two rear wheels of the vehicle, and the stability of the vehicle during crabbing turning is increased. BRIEF DESCRIPTION OF DRAWINGS

[0050] FIG. 1 is a block diagram of a control device according to some embodiments;

[0051] FIG. 2 is a schematic diagram of a functional architecture of various controller components in a control device, according to some embodiments;

[0052] FIG. 3 is a flowchart of an embodiment of a steering control method for a vehicle, according to some embodiments;

[0053] FIG. 4 is a schematic diagram of a vehicle, according to some embodiments;

[0054] FIG. 5 is a block diagram of an embodiment of an electric drive system, according to some embodiments;

[0055] FIG. 6 is a block diagram of a vehicle, according to some embodiments. DETAILED DESCRIPTION

[0056] In order to make the above objectives, features and advantages of the present disclosure more obvious and easy to understand, the present disclosure will be further described in detail below with reference to the drawings and specific embodiments.

[0057] In some embodiments, in order to solve the problem that the turning radius of the steering mode of the vehicle controlled by the driver steering the steering wheel to control the front wheel steering angle is large when the vehicle faces a narrow space or a complex environment, and the driver is difficult to pass through the narrow curved zone or bypass the obstacle at one time, and in order to improve the maneuverability and flexibility of the vehicle in the narrow space, the related art proposes a vehicle auxiliary steering technology (such as tank U-turn, U8 agile steering, etc.).

[0058] For example, in the case of the front wheels and the rear wheels of the vehicle steering in the same direction, based on the opposite driving torques applied to the front wheels and the rear wheels, the components of the driving forces generated on the front wheels and the rear wheels on the same side of the vehicle body in the longitudinal direction of the vehicle are equal in size and opposite in direction, the vehicle in a stationary state can not produce obvious displacement in the longitudinal direction, and substantially rotate around the center of mass of the vehicle, thereby reducing the turning radius of the vehicle.

[0059] However, the above-mentioned way of making the vehicle rotate around the center of the vehicle causes obvious jolts during the overall driving of the vehicle, and cannot realize fast steering or obstacle avoidance in urban narrow spaces. That is, after the vehicle enters the steering state, although the current vehicle auxiliary steering can help to reduce the turning radius of the vehicle, it is inevitable that the vehicle cannot pass through in some narrow spaces, and there is a possibility that the vehicle will be in danger.

[0060] To solve the above problems, some embodiments of the present disclosure provide a steering control method for a vehicle and a vehicle. The vehicle has a crab function.

[0061] When the crab function of the vehicle is activated and used, it can allow the vehicle to move laterally and realize crab motion.

[0062] FIG. 1 is a block diagram of a control device according to some embodiments, which can include a controller component, a memory, and a computer program stored on the memory, the computer program can be executed by the controller component to implement the steering control method of the vehicle according to some embodiments of the present disclosure.

[0063] As shown in FIG. 1, the controller component can include a vehicle control unit 10 (VCU), a display 11, a microcontroller unit 12 (MCU), a vehicle motion controller Didyna 13, an integrated power brake control system 14 (IPB), an electric power steering control system 15 (EPS), a rear wheel steering system 16 (RWS), an active suspension system Disus 17, and an electric park brake 18 (EPB).

[0064] In some embodiments, the above-mentioned controller component can perform double fault judgment when the crab function is turned on, and perform double activation processing after determining that the crab function is turned on without fault.

[0065] The double fault judgment can be mainly manifested by performing crab function fault judgment through the vehicle control unit 10, sending a crab function fault instruction to the vehicle motion controller 13, and then performing crab function fault judgment again based on the crab function fault instruction through the vehicle motion controller 13, so as to ensure the safety of the vehicle during crab motion based on double fault judgment.

[0066] The double activation processing can be mainly manifested by sending a crab function activation instruction to the vehicle control unit 10 through the vehicle motion controller 13, and then performing crab function activation judgment based on the crab function activation instruction through the vehicle control unit 10, so as to further ensure the safety of the vehicle during crab motion based on double activation processing.

[0067] In some embodiments, the display in the controller component can also be used to display the driving trajectory of the vehicle during crab motion in response to the crab function opening instruction, to further ensure the safety of the vehicle during crab motion. For example, the display 11 can be a panoramic assist display (PAD).

[0068] In some embodiments, the functional architecture of each controller component in the control device can be as shown in FIG. 2. When the user turns on the crab function through the PAD switch, i.e., the driver manually turns on the crab function through the PAD, the PAD can synchronize the driver's crab function demand to the vehicle controller VCU and the vehicle motion controller Didyna, send a configuration switch signal to the vehicle controller VCU and the vehicle motion controller Didyna, and the vehicle controller VCU and the vehicle motion controller Didyna can receive the crab function opening instruction. The vehicle controller VCU can perform crab function fault judgment, and after performing crab function fault judgment, can generate a crab function fault instruction based on the current crab function fault judgment result and send the crab function fault instruction to the vehicle motion controller Didyna, so that the vehicle motion controller Didyna can respond to the crab function fault instruction to perform crab function fault judgment again, for example, it can be manifested as obtaining vehicle fault information, analyzing the crab function fault judgment result performed by the aforementioned vehicle controller VCU, and in the case of determining that the fault state of the crab function is no fault, the vehicle motion controller Didyna can send a crab function start signal to the vehicle controller VCU, so that the vehicle controller VCU responds to the opening of the crab function, and realizes double fault judgment when the crab function is opened.

[0069] In some embodiments, when the vehicle motion controller Didyna detects a vehicle fault or a crab function fault, it means that the preset crab function opening condition cannot be met, at which time it can be fed back to the PAD synchronously, and the corresponding display is performed in the PAD interface to inform the user that the crab function is unavailable.

[0070] As shown in FIG. 2, after the vehicle motion controller Didyna sends the crab function start signal to the vehicle controller VCU, the vehicle motion controller Didyna can also perform preliminary crab function activation judgment on the vehicle driving information and the vehicle environment information to determine whether the crab function meets the preset activation condition. In the case of preliminarily determining that the crab function meets the preset activation condition, a crab function activation instruction is generated and sent to the vehicle controller VCU, and the vehicle controller VCU can perform crab function activation judgment again based on the crab function activation instruction, for example, based on the vehicle driving information and the vehicle environment information to determine whether the vehicle meets the preset activation condition. In the case of determining that the vehicle meets the preset activation condition, the crab function is activated to control the vehicle to perform crab motion based on the crab function.

[0071] In some embodiments of the present disclosure, when the crab function is activated, the two rear wheels of the vehicle can be controlled to steer in the same direction as the front wheel, and the two rear wheels of the vehicle can be controlled to have differential torque, so that the vehicle performs crab motion.

[0072] In some embodiments, after the crab function is activated, the vehicle motion controller can transmit the relevant information of the rear wheel steering angle to the vehicle controller, as shown in FIG. 2, for the vehicle controller to calculate the target differential torque, and then control the two rear wheels of the vehicle, for example, the motor control unit can respond to the target speed and target torque to control the two rear wheels accordingly, realizing differential torque control.

[0073] In practical applications, the PAD can send configuration switch signals to the vehicle controller VCU and the vehicle motion controller Didyna. The vehicle controller VCU can receive the function switch signal sent by the PAD. After the crab function is turned on, the PAD can receive the function switch signal sent by the vehicle motion controller Didyna. The steering control system EPS can send the steering wheel steering angle signal to the vehicle motion controller Didyna. In the case of crab function activation, the VCU can receive the crab function activation signal sent by the vehicle motion controller Didyna. The rear wheel steering system RWS can send the actual rear wheel steering angle signal to the vehicle motion controller Didyna and can receive the target rear wheel steering angle signal sent by the vehicle motion controller Didyna. The front motor control unit FMCU (Front Microcontroller Unit), the left rear motor control unit RLMCU (Rear Left Motor Control Unit), and the right rear motor control unit RRMCU (Rear Right Motor Control Unit) can send the actual torque signal to the vehicle controller VCU. At the same time, the vehicle controller VCU can send the throttle depth signal, the IMU signal (actual yaw rate and slope judgment), the front motor torque, the left rear wheel, the right rear wheel actual torque in real time, and calculate the target torque signal based on the foregoing information, and then send the target torque signal to the front motor control unit FMCU, the left rear motor control unit RLMCU, or the right rear motor control unit RRMCU, so that the front motor control unit FMCU, the left rear motor control unit RLMCU, or the right rear motor control unit RRMCU controls the actual torque based on the received target torque signal. In addition, the electronic parking system EPB can mainly receive the vehicle request of the vehicle motion controller Didyna, and feedback the actual state signal of the EPB. It should be noted that the above system components usually communicate with each other through the vehicle's Controller Area Network (CAN) bus to realize efficient data exchange and coordinated control.

[0074] In some embodiments, as shown in FIG. 2, the whole vehicle controller can perform trajectory calculation, for example, revising the current driving trajectory of the vehicle according to the yaw rate, and then outputting the revised driving trajectory to the display screen to assist the driver. The display of the revised driving trajectory can be represented as a pop-up panoramic interface displaying the vehicle turning trajectory, which is not limited in the present disclosure.

[0075] FIG. 3 is a flowchart of an embodiment of a steering control method of a vehicle according to some embodiments. The steering control method of a vehicle provided by some embodiments of the present disclosure can be implemented by the control device shown in FIG. 1, i.e., involving various controller components. The method can include the following step S301.

[0076] Step S301, when the crab function is activated, controlling the two rear wheels and the front wheel of the vehicle to steer in the same direction, and performing differential torque control on the two rear wheels of the vehicle to make the vehicle crab.

[0077] The crab function allows all wheels of the vehicle to steer in the same direction at the same angle, so that the vehicle can move in a nearly lateral manner. The speed control of this function is easy, the trajectory is easy to follow, the stability is good, the body shaking is small, and the wheel slipping and wear are acceptable to users. The road surface on which the crab function is applied can be all-terrain, and the basic application scenarios can include narrow road scenarios, parking scenarios, etc., such as the driver frequently steering to avoid obstacles on a narrow road, or parking or exiting a narrow road.

[0078] The crab function can control the two rear wheels and the front wheel of the vehicle to steer in the same direction, for example, the two rear wheels of the vehicle can be controlled to steer to a target steering angle, and the target steering angle is suitably set to any value between zero degrees and a steering threshold value.

[0079] As shown in FIG. 4, the front wheel steering angle and the rear wheel steering angle can have a 1:1 proportional relationship. Based on the steering center a, the rear wheel steering angle can be adjusted in real time following the front wheel steering angle, and the rear wheel steering angle is the same as the front wheel steering angle.

[0080] In actual application, when the user turns on the crab function through the PAD switch, for example, triggers the crab function demand through PAD operation or voice, etc., the user can operate the steering wheel to steer, and when the whole vehicle controller VCU and the whole vehicle motion controller Didyna perform fault judgment on the crab function and find no fault, the whole vehicle motion controller Didyna can control the rear wheel steering system RWS to control the rear wheel to follow the front wheel through the steering control system EPS.

[0081] The rear wheel steering system RWS has a limit of the limit of the rear wheel steering angle, that is, the limit of the limit of the rear wheel steering angle in the process of following adjustment with the front wheel steering angle, and the steering threshold of the rear wheel can refer to the limit of the rear wheel steering angle, for example, 10°.

[0082] In some embodiments of the present disclosure, during the process of controlling the two rear wheels of the vehicle to steer in the same direction with the front wheel, when the two rear wheels of the vehicle steer to the steering threshold of the rear wheel, there will be a certain angle gap between the rear axle steering angle and the front axle steering angle, at this time, the two rear wheels of the vehicle can be controlled by the activated crab function to compensate for the gap between the front axle steering angle and the rear axle steering angle based on the differential torque control, so as to realize the crab obstacle avoidance of a larger angle.

[0083] In some embodiments, the differential torque control performed by the crab function depends on the use of the crab function.

[0084] Firstly, the crab function can be turned on.

[0085] In some embodiments, the turning on of the crab function of the vehicle needs to be realized under the condition that the function opening requirement is met. For example, it can be manifested that the PAD can respond to the opening instruction of the crab function of the vehicle, and send the function opening signal to the vehicle controller VCU, which can be the function opening signal at present, at this time, the judgment result of whether the function opening requirement is met can be obtained in combination with the judgment of the crab function fault state of the vehicle motion controller and the judgment of the crab function fault state of the vehicle controller.

[0086] In some embodiments of the present disclosure, the fault judgment of the crab function can be performed by responding to the opening instruction of the crab function of the vehicle, obtaining the vehicle fault information, and judging whether the vehicle fault information meets the preset opening condition.

[0087] In some embodiments, the preset start condition can be represented as: 1) when the OK indicator light is OK; the motor permission start flag of the front motor control unit FMCU, the left rear motor control unit RLMCU or the right rear motor control unit RRMCU is permission; 2) the rotation speed valid flag bit of the front motor control unit FMCU, the left rear motor control unit RLMCU or the right rear motor control unit RRMCU is valid; 3) the maximum torque valid flag bit of the front motor control unit FMCU, the left rear motor control unit RLMCU or the right rear motor control unit RRMCU is valid; 4) the drive motor transmission ratio fault state is no fault; 5) the system state signal of the vehicle motion controller Didyna is valid; 6) the steering wheel angle valid flag bit is valid; 7) the steering wheel angle calibration flag bit is calibrated; 8) the steering wheel actual torque valid flag bit is valid; 9) the vehicle speed signal state is no fault; 10) the brake depth valid flag is valid; 11) the gear system state is normal; 12) the left rear wheel rotation angle valid flag bit or the right rear wheel rotation angle valid flag bit is valid. The present disclosure is not limited in this regard.

[0088] In some embodiments, the crab function can be activated in a case where it is determined based on the vehicle fault information that the fault state of the crab function is no fault.

[0089] In some embodiments of the present disclosure, if it is determined based on the vehicle driving information and the vehicle environment information that the vehicle satisfies the preset activation condition, the crab function can be activated, and differential torque control is performed on the two rear wheels of the vehicle to enable the vehicle to move in crab mode; if it is determined based on the vehicle driving information and the vehicle environment information that the vehicle does not satisfy the preset activation condition, the crab function is not activated.

[0090] Here, the vehicle driving information can include front wheel steering angle information, gear information and brake depth information, and the vehicle environment information can include slope information.

[0091] The preset activation condition can include that the front wheel steering angle information does not exceed (e.g., is less than or equal to) a preset angle threshold, the slope information does not exceed (e.g., is less than or equal to) a preset slope threshold, the brake depth information does not exceed (e.g., is less than or equal to) a preset depth threshold, and the gear information satisfies preset driving information, where the preset driving information can include preset forward driving information and preset reverse driving information.

[0092] In the above preset activation condition, the front wheel steering angle information not exceeding the preset angle threshold indicates that the vehicle needs to steer within a relatively small angle range; the slope information not exceeding the preset slope threshold can be to ensure the stability of the vehicle when moving laterally; the brake depth information not exceeding the preset depth threshold indicates that the driver does not apply excessive brake pressure to allow the vehicle to move laterally; and the gear information of the preset forward travel information and the preset reverse travel information indicates that the vehicle needs to move laterally in the forward or reverse state.

[0093] In some embodiments, the preset activation condition can be expressed as: 1) when the user operates the steering wheel, the front wheel steering angle is ≤ 15°; 2) the vehicle is on flat ground, i.e., the slope information of the vehicle driving environment is less than a preset slope threshold; 3) the brake depth information is less than a certain threshold; and 4) the gear is D / R gear. The present disclosure is not limited in this regard.

[0094] In actual application, the vehicle motion controller Didyna obtains the front wheel steering angle from the steering wheel angle signal sent by the steering control system EPS, and when it is determined that the front wheel steering angle is greater than a preset angle threshold, it can send a crab function activation instruction to the vehicle controller VCU, i.e., the vehicle motion controller Didyna can feed back an executable signal to the PAD and the vehicle controller VCU.

[0095] In some embodiments, when the vehicle motion controller Didyna receives and starts to execute the crab function, corresponding demand signals can be transmitted to the intelligent integrated brake control system IPB, the steering control system EPS, the rear wheel steering system RWS, the active suspension system Disus, and the electronic parking brake system EPB. Here, in order to ensure the passability and steering purpose of the vehicle, if an emergency occurs when the vehicle executes the crab function, the EPB can be triggered by the vehicle motion controller Didyna to perform emergency braking, thereby ensuring the safety of the vehicle when executing the crab function.

[0096] In some embodiments of the present disclosure, the differential torque control on the two rear wheels of the vehicle, for example, can be expressed as adjusting the steering center a as shown in FIG. 4 to reduce the turning radius of the vehicle by differentiating the torque on the rear axle.

[0097] In some embodiments, the differential torque control on the two rear wheels of the vehicle can be performed according to the difference between the front wheel steering angle and the rear wheel steering angle, and the differential torque of the rear axle, so as to increase the control dimension of the vehicle based on the differential torque control on the rear wheels, effectively enhance the control ability of the vehicle body posture during steering, reduce the turning radius of the vehicle, and make the vehicle more smooth during turning.

[0098] In actual implementation, the rear axle demand torque can be determined according to the difference between the front wheel steering angle and the rear wheel steering angle, and then the two rear wheels of the vehicle are controlled by differential torque according to the rear axle demand torque and the rear axle differential torque, so as to make the vehicle crab.

[0099] In some embodiments, the front wheel steering angle is in positive proportion to the steering wheel angle, and the rear axle differential torque can include a rear axle basic differential torque, which can be determined according to the steering wheel angle and the steering wheel torque according to a preset corresponding relationship.

[0100] In actual application, the current steering wheel angle and the steering wheel torque can be obtained, and then the rear axle basic differential torque corresponding to the current steering wheel angle and the steering wheel torque can be obtained based on a preset lookup table. For example, it can be obtained by unloading the unloading slope table or the steering wheel angle lookup table, which is not limited in the present disclosure.

[0101] In some embodiments, when the steering wheel angle is greater than a preset steering wheel angle threshold, for example, greater than 90°, and the steering wheel torque is less than or equal to a preset first torque threshold, for example, less than or equal to 1 Nm, and lasts for a certain period of time, for example, lasts for 100 ms, the rear axle basic differential torque T δ can be unloaded to 0 Nm according to the unloading slope table; when the steering wheel angle is greater than a preset steering wheel angle threshold, for example, greater than 90°, and the steering wheel torque is greater than or equal to a preset second torque threshold, for example, greater than or equal to 3 Nm, and lasts for a certain period of time, for example, lasts for 100 ms, the rear axle basic differential torque T δ can be obtained according to the control vehicle speed and the steering wheel angle lookup table.

[0102] In other embodiments, when the steering wheel angle is less than a preset steering wheel angle threshold, for example, less than 90°, and the steering wheel torque is greater than or equal to a preset third torque threshold, for example, greater than or equal to -1 Nm, and lasts for a certain period of time, for example, lasts for 100 ms, the rear axle basic differential torque T δ can be unloaded to 0 Nm according to the unloading slope table; when the steering wheel angle is less than a preset steering wheel angle threshold, for example, less than 90°, and the steering wheel torque is less than or equal to a preset fourth torque threshold, for example, less than or equal to -3 Nm, and lasts for a certain period of time, for example, lasts for 100 ms, the rear axle basic differential torque T δ can be obtained according to the control vehicle speed and the steering wheel angle lookup table. The present disclosure is not limited in this regard.

[0103] In some embodiments of the present disclosure, in order to control the two rear wheels of the vehicle by differential torque, in addition to obtaining the rear axle demand torque, the rear axle differential torque can also be obtained.

[0104] In some embodiments, the rear axle differential torque can further include a correction coefficient, and the rear axle differential torque can be calculated by the following formula: rear axle differential torque = rear axle basic differential torque x correction coefficient. Here, the correction coefficient can include at least one of a brake attenuation coefficient, a rear wheel torque coefficient, or a slope attenuation coefficient, and the numerical signs of the differential torques of the two rear wheels are different.

[0105] In some embodiments, the rear axle differential torque can further include a correction coefficient and a direction indication value, and the rear axle differential torque can be calculated by the following formula: rear axle differential torque = direction indication value x rear axle basic differential torque x correction coefficient. Here, the correction coefficient can include at least one of a brake attenuation coefficient, a rear wheel torque coefficient, or a slope attenuation coefficient, the direction indication value is positive when the steering direction of the vehicle is left, and the direction indication value is negative when the steering direction of the vehicle is right.

[0106] It should be noted that the direction indication value is positive when the steering direction of the vehicle is left, and the direction indication value is negative when the steering direction of the vehicle is right, i.e., the numerical signs of the left rear wheel differential torque and the right rear wheel differential torque are different, thereby ensuring that the right rear wheel differential torque is different from the left rear wheel differential torque, and further ensuring that the subsequent left and right rear wheel motors have different torque outputs.

[0107] In some embodiments, the calculation formula of the rear axle differential torque can be as shown in the following formula (1) and formula (2). Left rear wheel differential torque = direction indication value of steering direction of vehicle x rear axle basic differential torque T δ x brake attenuation coefficient x left rear wheel torque coefficient x slope attenuation coefficient x -1 (1) Right rear wheel differential torque = direction indication value of steering direction of vehicle x rear axle basic differential torque T δ x brake attenuation coefficient x right rear wheel torque coefficient x slope attenuation coefficient (2)

[0108] It should be noted that the brake attenuation coefficient, the torque attenuation coefficient, the slope attenuation coefficient, etc. can be obtained by looking up a table.

[0109] The relevant table examples can be as shown in the following table 1, table 2 and table 3:

[0110] Table 1

[0111] Table 2

[0112] Table 3

[0113] Here, C_APA can refer to a certain specific vehicle control or data recording system, and the basic rules presented in its table are as follows: the brake attenuation coefficient is negatively correlated with the brake depth, that is, the more obvious the brake, the smaller the differential torque, the larger the basic differential torque, and the greater the difference between the differential torques of the left and right wheels; the slope attenuation coefficient is negatively correlated with the slope, that is, the greater the slope, the smaller the differential torque. The present disclosure does not limit this.

[0114] In actual application, the differential torque based on the allocated differential torque can include the left rear wheel differential torque and the right rear wheel differential torque, at which time the motor target torque can be calculated.

[0115] In some embodiments, the left rear motor target torque can be calculated by obtaining the rear axle demand torque and then using the rear axle demand torque and the left rear wheel differential torque, and the right rear motor target torque can be calculated by using the rear axle demand torque and the right rear wheel differential torque.

[0116] The front axle demand torque and the rear axle demand torque can usually be calculated and allocated by the electronic control unit of the vehicle according to the dynamic demand of the vehicle and the operation of the driver. In actual application, the rear axle demand torque can be calculated based on the difference between the rear axle steering angle and the front axle steering angle when the vehicle crabbing is satisfied, for example, the rear axle demand torque can be calculated by obtaining the rear wheel steering angle limit value of the vehicle, then calculating the steering angle difference between the rear wheel steering angle limit value and the front wheel steering angle, and determining the rear axle torque based on the steering angle difference, and using the rear axle torque to calculate the rear axle demand torque.

[0117] In some embodiments, the motor target torque calculation formula of the crabbing function can be shown in the following formula (3) to formula (5). Front motor target torque = front axle demand torque (3) Left rear motor target torque = rear axle demand torque / 2 + left rear wheel differential torque (4) Right rear motor target torque = rear axle demand torque / 2 + right rear wheel differential torque (5)

[0118] In actual application, the target torque transmitted by the vehicle controller VCU to the MCU control unit of the front and rear three motors can be, for example, the left rear wheel target torque or the right rear wheel target torque.

[0119] In some embodiments, during the differential torque control of the two rear wheels of the vehicle, the vehicle can also be subjected to zero-torque smoothing control according to the current vehicle speed and the road adhesion coefficient of the vehicle.

[0120] In some embodiments, the crab function can be controlled by the vehicle control unit VCU according to the current vehicle speed, steering angle information, road adhesion coefficient and other parameters to ensure smooth torque output. The intelligent adjustment of the vehicle control unit VCU under different driving conditions can ensure the stability of the vehicle under low power output and meet the dynamic response requirements of the vehicle under high power output.

[0121] In some embodiments, the actual torque at the wheel end can be determined according to the current vehicle speed and the road adhesion coefficient, and the torque variation range of the crab function target torque output can be controlled based on the actual torque at the wheel end.

[0122] In some embodiments, the slope of torque loading and unloading can be adjusted under different actual torque conditions at the wheel end. For low torque control, for example, when the absolute value (abs) of the actual torque at the wheel end of all wheels is less than 40 Nm, the vehicle control unit VCU limits the loading and unloading slope of the front axle target torque, the left rear wheel target torque and the right rear wheel target torque to be less than or equal to 4 Nm, which means that the torque changes slowly to ensure smooth power output and avoid impact on the vehicle. For high torque control, for example, when the absolute value (abs) of the actual torque at the wheel end is greater than 54 Nm, the vehicle control unit VCU can allow a higher loading and unloading slope of the front axle target torque, the left rear wheel target torque and the right rear wheel target torque, which can be up to 100 Nm, so that the vehicle control unit VCU allows faster torque adjustment to adapt to more dynamic driving requirements when the vehicle has a high power output.

[0123] In some embodiments, the crab function target torque can also be limited according to the road adhesion coefficient during differential torque control of the two rear wheels of the vehicle.

[0124] In some embodiments, the target torque of the two rear wheels of the rear axle can be limited according to the calculation results of the traction control system (TCS) and the motor capacity. In some embodiments, if the rear wheel is determined to be slipping based on the road adhesion coefficient, the target torque at the wheel end of the rear wheel can be limited based on the torque of the rear wheel drive motor; if the rear wheel is determined not to be slipping based on the road adhesion coefficient, the target torque at the wheel end of the rear wheel can be limited based on the torque of the rear wheel drive motor and the rear wheel torque limit.

[0125] For the limit of the rear target torque, the torque limit value calculated by the TCS and the motor capacity can be used to limit the target torque of each wheel. The limit method of the two rear wheels is the same. Taking the left rear wheel as an example, when the left rear wheel slip state is 0 (i.e., not slipping), the following limit formula (6) is executed. -1x left rear motor maximum torque ≤ left rear wheel target torque ≤ left rear motor maximum torque (6)

[0126] It is illustrated that under normal circumstances, the target torque of the left rear wheel can be freely adjusted between the maximum positive torque and the maximum negative torque of the motor to meet the power demand of the vehicle.

[0127] When the left rear wheel slip state is 1 (i.e., slipping), the following limit formula (7) is executed. -1x left rear motor maximum torque ≤ left rear wheel target torque ≤ torque value min(left rear wheel torque limit, left rear motor maximum torque) (7)

[0128] That is, the torque value min can be selected as the smaller value of the left rear wheel torque limit and the left rear motor maximum torque. Here, the left rear wheel torque limit value can be the torque limit value calculated by the TCS to prevent the wheel from further slipping. It is illustrated that under the slipping state, the upper limit of the target torque of the left rear wheel can be the smaller value of the torque limit value calculated by the TCS and the motor maximum torque, to ensure that the wheel will not continue to slip due to excessive torque.

[0129] In some embodiments, the wheel slip and lock states can also be detected, and the control strategy of the vehicle can be adjusted accordingly to ensure that the vehicle remains stable and safe under various driving conditions. For example, when a wheel slip or lock tendency is detected, the system can reduce the torque output of the motor or apply a brake to the slipping wheel to restore traction and prevent the vehicle from losing control, which is not limited in the present disclosure.

[0130] Here, the wheel slip state = left rear wheel slip state || right rear wheel slip state, that is, when one of the left rear wheel or the right rear wheel slips, it is determined that the vehicle is in a slipping state. Here, when the difference between the reference speed (which can be the actual speed of the vehicle or a certain reference speed) and the crab speed (the speed of the vehicle in the crab mode) is greater than or equal to a preset first speed threshold, for example, greater than or equal to 1.5 km / h, it can be judged that the wheel has a reverse slip tendency, at which time the wheel lock state can be set to 1, indicating that the wheel may be about to or is currently experiencing lock; when the difference between the reference speed and the crab steering speed is less than or equal to a preset second speed threshold, for example, less than or equal to 1 km / h, the wheel state can be considered to be restored, at which time the wheel lock state can be set to 0, indicating that the wheel is no longer in a lock state.

[0131] In some embodiments, during the differential torque control of the two rear wheels of the vehicle, the current driving trajectory of the vehicle can also be revised according to the yaw rate, and the revised driving trajectory can be output to assist the driver.

[0132] In some embodiments of the present disclosure, during the corresponding control of the rear wheel steering, the actual yaw rate can also be obtained, and the current trajectory of the vehicle can be corrected based on the actual yaw rate, and the actual turning trajectory of the vehicle after correction can be displayed on the vehicle screen. As shown in FIG. 2, for example, after the crab function activation signal of the vehicle motion controller Didyna is received by the vehicle controller VCU, the vehicle controller can calculate the differential torque of the left and right wheels of the rear axle and send the target torque to the MCU in response, at the same time, the current trajectory correction state can be judged by the actual yaw rate and the like, and the trajectory calculation can be performed, the trajectory switching signal can be output to the PAD, so that the full-view interface can be popped up in the PAD and the actual turning trajectory of the vehicle can be displayed.

[0133] In some embodiments, the crab function of the vehicle can also be exited, and the exit condition can be opposite to the preset crab function opening condition, which is not limited in the present disclosure; for the exit condition of the crab function, it can be manifested that when the exit condition duration exceeds a certain time threshold, for example, exceeds 1000 ms, the rear axle basic differential torque T δ = 0 Nm, and the rear wheel steering angle is controlled to return to 0°, which is not limited in the present disclosure.

[0134] In some embodiments of the present disclosure, when the crab function is activated, the two rear wheels of the vehicle can be controlled to steer in the same direction as the front wheels, and the differential torque control can be performed on the two rear wheels of the vehicle to compensate for the difference between the front axle steering angle and the rear axle steering angle based on the differential torque control, so that the vehicle crab motion is realized, a larger crab obstacle avoidance is achieved, and the turning radius of the vehicle is reduced, so as to achieve the purpose of rapid turning or obstacle avoidance in the city narrow space. In some embodiments, the point-to-point oblique motion with almost no yaw can also be achieved by the intervention of the differential torque control of the two rear wheels of the vehicle, and the stability of the vehicle during the crab turning process can be improved.

[0135] It should be noted that for the method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that some steps can be performed in other order or simultaneously according to some embodiments of the present disclosure. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the involved actions are not necessarily required by some embodiments of the present disclosure.

[0136] FIG. 5 is a block diagram of an embodiment of an electric drive system according to some embodiments. As shown in FIG. 5, the electric drive system 5 can include:

[0137] One motor at the front end, for example, the first motor 51, is configured to output torque to the two front wheels of the vehicle; two motors at the rear end, for example, the second motor 52 and the third motor 53, are configured to output torque to the two rear wheels of the vehicle, and a control device 54 as shown in FIG. 5.

[0138] In some embodiments, when the crab function is activated and the Didyna sends a large-angle crab request, the vehicle controller VCU can calculate the target differential torque, transmit the received executable signal and the calculated left rear wheel motor target torque and right rear wheel motor target torque to the MCU control unit of the front and rear three motors, so that the MCU control unit is ready to execute the torque and differential torque control requirements required by the crab function, and responds to the target speed and target torque.

[0139] In actual application, the target torque finally transmitted by the vehicle controller VCU to the MCU control unit of the front and rear three motors, for example, is the left rear wheel target torque or the right rear wheel target torque, and the MCU control unit of the front and rear three motors can control the rear wheel steering according to the left rear wheel motor target torque and the right rear wheel motor target torque.

[0140] In some embodiments of the present disclosure, in order to reduce the turning radius of the vehicle, the front wheel steering angle controlled by the steering wheel and the activated crab function are received, so that the vehicle controller outputs different torques to the left and right wheel motors and the rear wheel motors to make up for the difference between the front axle steering angle and the rear axle steering angle, achieve a larger angle of crab obstacle avoidance, and thus help to reduce the turning radius of the vehicle, so that the vehicle can pass through the narrow road more easily and park more easily, achieve the purpose of quick turning or obstacle avoidance in the city narrow space, and thus improve the passability of the vehicle in extreme working conditions and the driving experience of the user. Here, the corresponding control strategy can be determined based on the front wheel steering angle, the rear wheel steering is combined with the differential torque based on the three-motor control architecture, the target driving torque of the front axle motor, the target driving torque of the left rear motor and the target driving torque of the right motor are redistributed, and different sizes of driving torques are allocated to the two rear wheels.

[0141] In some embodiments, when the front wheel steering angle is greater than a preset angle threshold, the point-to-point oblique motion with almost no yaw can be achieved by the intervention of the differential torque of the two rear wheel motors, and the stability of the vehicle during the crab turning process is increased.

[0142] In addition, the control device provided by some embodiments of the present disclosure can be applied to drivers with different experiences and different driving scenarios, which is not limited by the present disclosure.

[0143] As shown in FIG. 6, some embodiments of the present disclosure further provide a vehicle 100, comprising:

[0144] The control device or the electric drive system 5 described above enables the vehicle to implement each process of the embodiments of the vehicle steering control method described above and achieve the same technical effects. To avoid repetition, details are not described herein.

[0145] Some embodiments of the present disclosure further provide a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement each process of the embodiments of the vehicle steering control method described above and achieve the same technical effects. To avoid repetition, details are not described herein.

[0146] Each of the embodiments in the present specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0147] Those skilled in the art should understand that the embodiments of the present disclosure can be provided as a method, device, or computer program product. Therefore, some embodiments of the present disclosure can be in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. In addition, some embodiments of the present disclosure can be in the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, compact disc read-only memory (CD-ROM), optical storage, etc.) containing computer-usable program code.

[0148] Some embodiments of the present disclosure are described with reference to flowcharts and / or block diagrams of methods, terminal vehicles (systems), and computer program products according to some embodiments of the present disclosure. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal vehicle processor to produce a machine, so that the instructions executed by the computer or other programmable data processing terminal vehicle processor produce a device that implements the functions specified in one or more flows in the flowcharts and / or one or more blocks in the block diagrams.

[0149] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks and / or block or blocks of the block diagram.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer-implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart block or blocks and / or block or blocks of the block diagram.

[0151] Although preferred embodiments of some of the embodiments of the present disclosure have been described, those skilled in the art will, upon acquiring the basic inventive concept, make additional changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of some of the embodiments of the present disclosure.

[0152] Finally, it should be noted that the user information (including but not limited to user vehicle information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present disclosure are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation portal for user to choose authorization or refusal.

[0153] It should also be noted that in this document, relational terms such as first and second and the like can only be used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or terminal. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or terminal including the element.

[0154] The above describes in detail the steering control method of the vehicle, the corresponding control device, the corresponding electric drive system, the corresponding vehicle and the corresponding computer readable storage medium provided by the present disclosure. The principles and implementation manners of the present disclosure are described by applying specific examples. The above description of the examples is only used to help understand the method and core idea of the present disclosure. Moreover, for those skilled in the art, according to the idea of the present disclosure, the specific implementation manners and application ranges can be changed. In summary, the content of the specification should not be understood as a limitation of the present disclosure.

Claims

1. A steering control method of a vehicle, comprising: controlling two rear wheels of the vehicle to steer in the same direction as a front wheel and controlling the two rear wheels of the vehicle to be differentially torqued when a crab function is activated, so as to make the vehicle crab. 2.The steering control method of claim 1, further comprising: controlling the two rear wheels of the vehicle to steer to a target steering angle, the target steering angle being adapted to be set to any value between zero degrees and a steering threshold value.

3. The steering control method according to claim 2, wherein The target steering angle is the steering threshold value of the rear wheels.

4. The turning control method according to any one of claims 1 to 3, wherein The controlling the two rear wheels of the vehicle to be differentially torqued, comprises: controlling the two rear wheels of the vehicle to be differentially torqued according to a difference between a front wheel steering angle and a rear wheel steering angle and a rear axle differential torque, so as to make the vehicle crab.

5. The steering control method according to claim 4, wherein The controlling the two rear wheels of the vehicle to be differentially torqued according to a difference between a front wheel steering angle and a rear wheel steering angle and a rear axle differential torque, so as to make the vehicle crab, comprises: determining a rear axle required torque according to the difference between the front wheel steering angle and the rear wheel steering angle; controlling the two rear wheels of the vehicle to be differentially torqued according to the rear axle required torque and the rear axle differential torque, so as to make the vehicle crab.

6. The steering control method according to claim 5, wherein The front wheel steering angle is in a positive proportion to a steering wheel angle.

7. The steering control method according to claim 5, wherein The rear axle differential torque comprises a rear axle base differential torque, the rear axle base differential torque being determined according to a steering wheel angle and a steering wheel torque according to a preset corresponding relationship.

8. The steering control method according to claim 7, wherein The rear axle differential torque further comprises a correction coefficient, the rear axle differential torque = the rear axle base differential torque × the correction coefficient. The correction coefficient comprises at least one of a brake attenuation coefficient, a rear wheel torque coefficient or a slope attenuation coefficient, and the differential torque of the two rear wheels has different numerical signs.

9. The steering control method according to claim 7, wherein The rear axle differential torque further comprises a correction coefficient and a direction indication value, the rear axle differential torque = the direction indication value × the rear axle base differential torque × the correction coefficient. The correction coefficient comprises at least one of a brake attenuation coefficient, a rear wheel torque coefficient or a slope attenuation coefficient; wherein the direction indication value is positive when the steering direction of the vehicle is left, and the direction indication value is negative when the steering direction of the vehicle is right.

10. The steering control method according to claim 8 or 9, wherein The brake attenuation coefficient is in a negative correlation with a brake depth.

11. The steering control method according to claim 8 or 9, wherein The slope attenuation coefficient is in a negative correlation with a slope.

12. The steering control method according to claim 1, wherein The controlling the two rear wheels of the vehicle to be differentially torqued, so as to make the vehicle crab, comprises: if it is determined that the vehicle meets a preset activation condition based on vehicle driving information and vehicle environment information, activating the crab function and controlling the two rear wheels of the vehicle to be differentially torqued, so as to make the vehicle crab; if it is determined that the vehicle does not meet the preset activation condition based on the vehicle driving information and the vehicle environment information, not activating the crab function.

13. The steering control method according to claim 12, wherein The vehicle driving information comprises front wheel steering angle information, gear information and brake depth information, and the vehicle environment information comprises slope information. The preset activation condition comprises that the front wheel steering angle information does not exceed a preset angle threshold value, the slope information does not exceed a preset slope threshold value, the brake depth information does not exceed a preset depth threshold value and the gear information meets a preset driving information. The preset driving information includes preset forward driving information and preset reverse driving information.

14. The steering control method of claim 4, further comprising: performing zero-torque smoothing control on the vehicle according to a current vehicle speed and a road adhesion coefficient of the vehicle.

15. The steering control method according to claim 14, wherein The zero-torque smoothing control on the vehicle according to the current vehicle speed and the road adhesion coefficient of the vehicle comprises: determining a wheel-end actual torque according to the current vehicle speed and the road adhesion coefficient of the vehicle; controlling a torque variation amplitude when a crab function target torque is output based on a torque range of the wheel-end actual torque.

16. The steering control method of claim 14, further comprising: limiting the crab function target torque according to the road adhesion coefficient.

17. The steering control method according to claim 16, wherein The limiting of the crab function target torque according to the road adhesion coefficient comprises: if it is determined that the rear wheels are slipping based on the road adhesion coefficient, limiting the rear wheel-end target torque based on a rear wheel drive motor torque; if it is determined that the rear wheels are not slipping based on the road adhesion coefficient, limiting the rear wheel-end target torque based on the rear wheel drive motor torque and a rear wheel torque limit.

18. The steering control method of claim 4, further comprising: revising a current driving trajectory of the vehicle according to a yaw rate.

19. The steering control method of claim 18, further comprising: outputting a display of the revised driving trajectory to assist a driver in driving.

20. A control device comprising a controller assembly, a memory, and a computer program stored on the memory, the computer program being executed by the controller assembly to implement the steering control method of the vehicle according to any one of claims 1 to 19.

21. The control device of claim 20, wherein, The controller assembly comprises a vehicle controller, a vehicle motion controller, and a motor control unit.

22. The control device of claim 21, wherein, The vehicle controller performs a crab function failure judgment and sends a crab function failure instruction to the vehicle motion controller; the vehicle motion controller performs the crab function failure judgment again based on the crab function failure instruction.

23. The control device of claim 21, wherein, The vehicle motion controller sends a crab function activation instruction to the vehicle controller, and the vehicle controller performs a crab function activation judgment based on the crab function activation instruction.

24. The control device of claim 20, wherein, The controller assembly further comprises a display configured to display a driving trajectory of the vehicle in crab motion in response to the crab function activation instruction.

25. An electric drive system comprising: a front-end motor configured to output a torque to two front wheels of the vehicle; and two rear-end motors configured to output a torque to two rear wheels of the vehicle. and the control device according to any one of claims 20 to 24.

26. A vehicle comprising: the control device according to any one of claims 20 to 24; or the electric drive system according to claim 25. The computer readable storage medium stores a computer program, which, when executed by a processor, implements the steering control method of the vehicle according to any one of claims 1 to 19. ​ 27. A computer readable storage medium, wherein, ​

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