A steering control method and device of a vehicle, a vehicle and a storage medium

Abstract

The application provides a steering control method and device of a vehicle, the vehicle and a storage medium. The method comprises the following steps: determining an anchor point wheel, a steering direction and a given rotation angle of a wheel on a non-anchor point shaft; determining a first feedforward torque of a first motor and a second feedforward torque of a second motor; obtaining a first correction torque and a second correction torque through torque feedback control; determining a first target torque according to the first feedforward torque and the first correction torque and determining a second target torque according to the second feedforward torque and the second correction torque; controlling the anchor point wheel to brake and controlling the wheel on the non-anchor point shaft to rotate; when the anchor point wheel is in the braking state and the wheel on the non-anchor point shaft rotates to the given rotation angle, controlling the first motor to output the first target torque and the second motor to output the second target torque, so that the vehicle turns around the anchor point wheel in the steering direction. The method can solve the problem of difficulty in driving into and out of a narrow parking space, reduce the driving difficulty and improve the driving convenience.

Description

Technical Field

[0001] This application relates to the field of vehicles, and more specifically, to a steering control method, apparatus, vehicle, and storage medium for a vehicle. Background Technology

[0002] With rapid economic development, automobiles have become increasingly integral to people's lives, leading to a surge in vehicles on the road and a growing shortage of parking spaces. This has increased the difficulty of driving and parallel parking, consequently reducing the convenience of travel. Furthermore, the reduced parallel parking space makes it easier for drivers to scrape adjacent vehicles when entering and exiting parking spaces, resulting in economic losses. Driving pleasure is also gradually diminishing, impacting people's lives from various angles. Therefore, solving the problem of difficult entry and exit from narrow parallel parking spaces, reducing driving difficulty, and improving driving convenience has become an urgent technical challenge. Summary of the Invention

[0003] This application provides a vehicle steering control method, device, vehicle, and storage medium. The method can solve the problem of difficulty in entering and exiting narrow side parking spaces, reduce driving difficulty, and improve driving convenience.

[0004] In a first aspect, a vehicle steering control method is provided, comprising: determining an anchor wheel, a steering direction, and a given angle of rotation of wheels on non-anchor axles; wherein the axle containing the anchor wheel is the anchor axle, and the non-anchor axles are axles on the vehicle other than the anchor axle; determining a first feedforward torque of a first motor on the anchor axle, and determining a second feedforward torque of a second motor on the non-anchor axle; performing torque feedback control on the first motor to obtain a first corrected torque of the first motor, and performing torque feedback control on the second motor to obtain a second corrected torque of the second motor; determining a first target torque of the first motor based on the first feedforward torque and the first corrected torque, and determining a second target torque of the second motor based on the second feedforward torque and the second corrected torque; controlling the anchor wheel to brake, and controlling the wheels on the non-anchor axles to rotate according to the given angle; when the anchor wheel is in a braking state and the wheels on the non-anchor axles have rotated to the given angle, controlling the first motor to output the first target torque and the second motor to output the second target torque, so that the vehicle turns around the anchor wheel in the steering direction.

[0005] The aforementioned technical solution, through braking of the anchor point wheels and precise control of the non-anchor point axle wheels, as well as feedforward and feedback control of the motors, enables the vehicle to perform efficient and stable steering around the anchor point wheels in confined spaces. For the defined anchor point wheels, braking of these wheels ensures vehicle stability during steering, reducing the risk of loss of control and enhancing driving safety. For the wheels on the non-anchor point axles, precise control of their turning angles allows the driver to complete steering without frequent steering wheel adjustments, reducing driving burden and improving driving convenience. Simultaneously, feedforward and feedback control of the torque of the first and second motors ensures the vehicle's steering posture and precision around the anchor point wheels, improving steering accuracy in confined spaces, avoiding collisions with surrounding vehicles, reducing driver psychological stress during steering in confined spaces, and enhancing driving pleasure and satisfaction.

[0006] In conjunction with the first aspect, in some possible implementations, determining the first feedforward torque of the first motor on the anchor point shaft and the second feedforward torque of the second motor on the non-anchor point shaft includes: determining the first slip limit torque corresponding to the anchor point shaft and determining the second slip limit torque corresponding to the non-anchor point shaft; wherein the first slip limit torque characterizes the minimum torque required for the wheel on the anchor point shaft to exceed the slip limit; the second slip limit torque characterizes the minimum torque required for the wheel on the non-anchor point shaft to exceed the slip limit; determining the first feedforward torque of the first motor based on the first slip limit torque; wherein the first feedforward torque is less than or equal to the first slip limit torque; determining the second feedforward torque of the second motor based on the second slip limit torque; wherein the second feedforward torque is greater than or equal to the second slip limit torque.

[0007] In combination with the first aspect and the above implementation methods, in some possible implementation methods, determining the first slip limit torque corresponding to the anchor point shaft and determining the second slip limit torque corresponding to the non-anchor point shaft includes: determining the first static load of the anchor point shaft and determining the second static load of the non-anchor point shaft; obtaining the first efficiency of the first motor, the second efficiency of the second motor, the first speed ratio of the first reducer located on the anchor point shaft, the second speed ratio of the second reducer located on the non-anchor point shaft, the wheel radius, and the road surface adhesion coefficient; calculating the first slip limit torque corresponding to the anchor point shaft based on the first efficiency, the first speed ratio, the first static load, the road surface adhesion coefficient, and the wheel radius; and calculating the second slip limit torque corresponding to the non-anchor point shaft based on the second efficiency, the second speed ratio, the second static load, the given turning angle, the road surface adhesion coefficient, and the wheel radius.

[0008] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the step of performing torque feedback control on the first motor to obtain the first corrected torque of the first motor includes: obtaining the actual wheel speed and target wheel speed of the non-anchor wheel on the anchor point axle; obtaining the actual longitudinal resultant force and target longitudinal resultant force of the vehicle; performing PID control on the first difference between the actual wheel speed and the target wheel speed, or performing PID control on the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the first corrected torque of the first motor.

[0009] In conjunction with the first aspect and the above implementation methods, in some possible implementation methods, the step of performing PID control on the first difference between the actual wheel speed and the target wheel speed, or performing PID control on the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the first corrected torque of the first motor, includes: when the actual wheel speed is within a set wheel speed range and the actual longitudinal resultant force is not within a set resultant force range, performing PID control on the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the first corrected torque of the first motor; and when the actual wheel speed is not within a set wheel speed range and the actual longitudinal resultant force is within a set resultant force range, performing PID control on the first difference between the actual wheel speed and the target wheel speed to obtain the first corrected torque of the first motor.

[0010] In combination with the first aspect and the above implementation, in some possible implementations, the method further includes: when the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, controlling the vehicle to stop steering and performing braking control on the vehicle.

[0011] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the target wheel speed of the non-anchor wheel on the anchor point axle is determined by: obtaining the vehicle's current actual yaw rate, wheel track, and target wheel speed sign coefficient; and using the product of the actual yaw rate, the wheel track, and the target wheel speed sign coefficient as the target wheel speed.

[0012] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the step of performing torque feedback control on the second motor to obtain the second corrected torque of the second motor includes: obtaining the actual wheel speed average value and the target wheel speed average value of the left wheel and the right wheel on the non-anchor point axle; and performing PID control on the third difference between the actual wheel speed average value and the target wheel speed average value to obtain the second corrected torque of the second motor.

[0013] Secondly, a vehicle control device is provided, comprising: a first determining module for determining a given turning angle of a vehicle's anchor wheel, a steering direction, and wheels on non-anchor axles; wherein the axle containing the anchor wheel is an anchor axle, and the non-anchor axles are axles on the vehicle other than the anchor axle; a feedforward torque determining module for determining a first feedforward torque of a first motor on the anchor axle and a second feedforward torque of a second motor on the non-anchor axle; and a feedback control module for performing torque feedback control on the first motor to obtain a first corrected torque of the first motor and performing torque feedback control on the second motor to obtain a second corrected torque of the second motor. The second determining module is used to determine the first target torque of the first motor based on the first feedforward torque and the first corrected torque, and to determine the second target torque of the second motor based on the second feedforward torque and the second corrected torque; the first control module is used to control the braking of the anchor wheel and to control the rotation of the wheel on the non-anchor wheel according to the given turning angle; the second control module is used to control the first motor to output the first target torque and the second motor to output the second target torque when the anchor wheel is in a braking state and the wheel on the non-anchor wheel has rotated to the given turning angle, so that the vehicle turns around the anchor wheel in the turning direction.

[0014] Thirdly, a vehicle is provided, including a memory for storing executable program code; and a processor for calling and running the executable program code from the memory, causing the vehicle to perform the method described in the first aspect or any possible implementation thereof.

[0015] Fourthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof.

[0016] Fifthly, a computer-readable storage medium is provided that stores computer program code, which, when executed on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a vehicle steering control method provided in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of a vehicle turning counterclockwise around the left front wheel, provided in an embodiment of this application.

[0019] Figure 3 This is a schematic diagram illustrating a vehicle turning clockwise around its left front wheel, as provided in an embodiment of this application.

[0020] Figure 4 This is a schematic diagram of a vehicle turning counterclockwise around the right front wheel, provided in an embodiment of this application.

[0021] Figure 5 This is a schematic diagram illustrating a vehicle turning clockwise around its right front wheel, as provided in an embodiment of this application.

[0022] Figure 6 This is a schematic diagram of a vehicle turning counterclockwise around the left rear wheel, as provided in an embodiment of this application.

[0023] Figure 7 This is a schematic diagram illustrating a vehicle turning clockwise around the left rear wheel, as provided in an embodiment of this application.

[0024] Figure 8 This is a schematic diagram of a vehicle turning counterclockwise around the right rear wheel, provided in an embodiment of this application.

[0025] Figure 9 This is a schematic diagram of a vehicle turning clockwise around the right rear wheel, provided in an embodiment of this application.

[0026] Figure 10 This is a schematic diagram illustrating the principle of PID control of the first difference provided in an embodiment of this application;

[0027] Figure 11 This is a schematic diagram illustrating the principle of PID control for the second difference provided in an embodiment of this application;

[0028] Figure 12 This is a schematic diagram illustrating the principle of PID control for a third difference provided in an embodiment of this application;

[0029] Figure 13 This is a schematic diagram of a steering control method provided in an embodiment of this application;

[0030] Figure 14 This is a schematic diagram of the structure of a vehicle control device provided in an embodiment of this application;

[0031] Figure 15 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0032] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0033] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0034] With rapid economic development, automobiles have become increasingly integral to people's lives, leading to a surge in vehicles on the road and a growing shortage of parking spaces. This has increased the difficulty of driving and parallel parking, consequently reducing the convenience of travel. Furthermore, the reduced parallel parking space makes it easier for drivers to scrape adjacent vehicles when entering and exiting parking spaces, resulting in economic losses. Driving pleasure is also gradually diminishing, impacting people's lives from various angles. Therefore, solving the problem of difficult entry and exit from narrow parallel parking spaces, reducing driving difficulty, and improving driving convenience has become an urgent technical challenge.

[0035] Based on this, to at least solve the aforementioned technical problems, this application provides a vehicle steering control method, applied to a vehicle model equipped with rear-wheel steering and decoupled front-to-rear axle drive. Rear-wheel steering means that the rear wheels of the vehicle can actively steer in addition to the traditional passive following action. Decoupled front-to-rear axle drive means that the power transmission between the front and rear axles is independently controlled. That is, power can be dynamically distributed between the front and rear axles according to the vehicle's needs, rather than in a fixed ratio or with complete mechanical linkage.

[0036] This embodiment provides a control function for a four-wheel steering vehicle to steer around any of its wheels. If the vehicle needs to park in a tight parallel parking space, in a scenario where parking is difficult, a suitable wheel can be selected as an anchor wheel, and the vehicle can be controlled to steer around the anchor wheel to achieve the parking maneuver. If the vehicle needs to exit a tight parallel parking space, in a scenario where exiting is difficult, a suitable wheel can be selected as an anchor wheel, and the vehicle can be controlled to steer around the anchor wheel to achieve the exit maneuver. If the vehicle is in a narrow road or a scenario where U-turns are difficult, a suitable wheel can be selected as an anchor wheel, and the vehicle can steer around the anchor wheel to achieve the U-turn maneuver. In this embodiment, by controlling the vehicle to steer around the anchor wheels, it can assist the driver in driving the vehicle into and out of tight parallel parking spaces, and can also assist the driver in making U-turns on narrow roads.

[0037] Figure 1 This is a schematic flowchart of a vehicle steering control method provided in an embodiment of this application.

[0038] For example, such as Figure 1 As shown, the method includes:

[0039] Step 101: Determine the given turning angles of the anchor wheel, steering direction, and wheels on non-anchor axles of the vehicle; where the axle containing the anchor wheel is the anchor axle, and the non-anchor axles are the axles on the vehicle other than the anchor axles.

[0040] Step 102: Determine the first feedforward torque of the first motor on the anchor point axis, and determine the second feedforward torque of the second motor on the non-anchor point axis.

[0041] Step 103: Perform torque feedback control on the first motor to obtain the first corrected torque of the first motor, and perform torque feedback control on the second motor to obtain the second corrected torque of the second motor.

[0042] Step 104: Determine the first target torque of the first motor based on the first feedforward torque and the first correction torque, and determine the second target torque of the second motor based on the second feedforward torque and the second correction torque.

[0043] Step 105: Control the braking of the anchor point wheel and control the rotation of the wheels on the non-anchor point axle according to the given turning angle.

[0044] Step 106: When the anchor wheel is in a braking state and the wheels on the non-anchor axle are rotated to a given angle, control the first motor to output a first target torque and the second motor to output a second target torque so that the vehicle turns around the anchor wheel in the aforementioned steering direction.

[0045] exist Figure 1In the illustrated embodiment, through braking of the anchor point wheels and precise control of the non-anchor point axle wheels, as well as feedforward and feedback control of the motors, efficient and stable steering around the anchor point wheels is achieved in confined spaces. For the defined anchor point wheels, braking ensures vehicle stability during steering, reduces the risk of loss of control, and enhances driving safety. For the wheels on the non-anchor point axles, precise control of their turning angles allows the driver to complete steering without frequent steering wheel adjustments, reducing driving burden and improving driving convenience. Simultaneously, torque control of the first and second motors through feedforward and feedback control ensures the vehicle's steering posture and precision around the anchor point wheels, improving steering accuracy in confined spaces, avoiding collisions with surrounding vehicles, reducing driver stress during steering in confined spaces, and enhancing driving pleasure and satisfaction.

[0046] The following is about Figure 1 The specific implementation methods of each step in the illustrated embodiment are explained below:

[0047] In step 101, the anchor wheel can be a wheel selected by the driver from among the wheels of the vehicle. The anchor wheel is used to indicate the direction around which the vehicle turns. The driver can select an anchor wheel from among the wheels of the vehicle based on the vehicle's current position and the target position the vehicle needs to reach, and select a steering direction. This steering direction can be clockwise or counterclockwise.

[0048] It is understandable that a vehicle's wheels generally include: the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel. The driver can choose one of these four wheels as the anchor wheel.

[0049] For example, the driver can first activate the anchor point steering function via a function switch. For instance, the central control screen can display a function switch for the anchor point steering function. When the driver touches the function switch, the anchor point steering function is activated, and a prompt interface is displayed on the central control screen. This prompt interface can guide the driver to select the anchor point wheel and steering direction, and confirm the driver's selected anchor point wheel and steering direction.

[0050] For example, the driver can also select road surface information and a target location. The road surface information can be: dry or wet asphalt road, dry or wet cement road, dirt road, etc. Based on the road surface information selected by the driver, the road adhesion coefficient of the vehicle's current location can be determined. The target location is the position where the vehicle should stop during steering, i.e., the position where the vehicle should stop during the steering process around the anchor point.

[0051] For example, after determining the anchor wheel of a vehicle, a given steering angle of the wheel on the non-anchor axle can be further determined. The axle containing the anchor wheel is the anchor axle, and the non-anchor axles are the axles on the vehicle other than the anchor axles. It is understood that the axles of a vehicle include: the front axle and the rear axle, one of the anchor axle and the other of the non-anchor axle being the front axle and the other the rear axle.

[0052] If the left front wheel is chosen as the anchor point wheel, then the anchor point axle is the front axle, and the non-anchor point axle is the rear axle. The non-anchor point wheels on the anchor point axle are the right front wheels, and the wheels on the non-anchor point axles are the left and right rear wheels.

[0053] If the right front wheel is chosen as the anchor point wheel, then the anchor point axle is the front axle, and the non-anchor point axle is the rear axle. The non-anchor point wheels on the anchor point axle are the left front wheels, and the wheels on the non-anchor point axles are the left and right rear wheels.

[0054] If the left rear wheel is chosen as the anchor point wheel, then the anchor point axle is the rear axle, and the non-anchor point axle is the front axle. The non-anchor point wheel on the anchor point axle is the right rear wheel, and the wheels on the non-anchor point axle are the left front wheel and the right front wheel.

[0055] If the right rear wheel is chosen as the anchor point wheel, then the anchor point axle is the rear axle, and the non-anchor point axle is the front axle. The non-anchor point wheel on the anchor point axle is the left rear wheel, and the wheels on the non-anchor point axle are the left front wheel and the right front wheel.

[0056] The given steering angle represents the angle to which the two wheels on the non-anchor axle should rotate before the first and second motors output the first and second target torques, respectively. This given steering angle can be based on the pre-calibrated anchor wheels; that is, there is a preset correspondence between the anchor wheels and the given steering angle. Once the anchor wheels are determined, the given steering angle can be determined by combining this correspondence. Typically, if the rear wheel is selected as the anchor wheel, the given steering angle value may be around 10°; if the driver selects the front wheel as the anchor wheel, the given steering angle value may be greater than 10°. The direction of the given steering angle can be either left or right, providing a steering basis for the vehicle to turn around the anchor wheels according to the steering direction. When the wheel on the non-anchor axle deflects to the left by a given angle, the torque direction corresponding to the wheel on the non-anchor axle is the first direction; when the wheel on the non-anchor axle deflects to the right by a given angle, the torque direction corresponding to the wheel on the non-anchor axle is the second direction. The first and second directions are different.

[0057] In one possible implementation, the anchor wheel is the left front wheel, and the steering direction is counterclockwise. A diagram illustrating the vehicle's counterclockwise steering around the left front wheel can be found here. Figure 2 .like Figure 2 As shown, the vehicle includes a left front wheel 201 and a right front wheel 202 located on the front axle, and a left rear wheel 203 and a right rear wheel 204 located on the rear axle. Figure 2 In the middle, the two wheels on the non-anchor point axle are the left rear wheel 203 and the right rear wheel 204, and the angle to which the left rear wheel 203 and the right rear wheel 204 rotate is a given angle θ1. Figure 2 In the given angle θ1, the direction is rightward deflection. In a specific implementation, the direction of the given angle θ1 can also be leftward deflection. In this case, the torque direction corresponding to the left rear wheel 203 and the right rear wheel 204 is different from the torque direction corresponding to the left rear wheel 203 and the right rear wheel 204 when the given angle θ1 is rightward deflection.

[0058] In one possible implementation, the anchor wheel is the left front wheel, and the steering direction is clockwise. A diagram illustrating the vehicle's clockwise steering around the left front wheel can be found here. Figure 3 .like Figure 3 As shown, the two wheels on the non-anchor point axle are the left rear wheel 203 and the right rear wheel 204, and the angle to which the left rear wheel 203 and the right rear wheel 204 rotate is a given angle θ2. Figure 3 In the given angle θ2, the direction is to the left.

[0059] In one possible implementation, the anchor wheel is the right front wheel, and the steering direction is counterclockwise. A diagram illustrating the vehicle's counterclockwise steering around the right front wheel can be found in [reference needed]. Figure 4 .like Figure 4 As shown, the two wheels on the non-anchor point axle are the left rear wheel 203 and the right rear wheel 204, and the angle to which the left rear wheel 203 and the right rear wheel 204 rotate is a given angle θ3. Figure 4 In the given angle θ3, the direction is to deflect to the left.

[0060] In one possible implementation, the anchor wheel is the right front wheel, and the steering direction is clockwise. A diagram illustrating the vehicle's clockwise steering around the right front wheel can be found in [reference needed]. Figure 5 .like Figure 5 As shown, the two wheels on the non-anchor point axle are the left rear wheel 203 and the right rear wheel 204, and the angle to which the left rear wheel 203 and the right rear wheel 204 rotate is a given angle θ4. Figure 5 In the given angle θ4, the direction is a rightward deflection.

[0061] In one possible implementation, the anchor wheel is the left rear wheel, and the steering direction is counterclockwise. A diagram illustrating the vehicle's counterclockwise steering around the left rear wheel can be found in [reference needed]. Figure 6 .like Figure 6 As shown, the two wheels on the non-anchor point axle are the left front wheel 201 and the right front wheel 202, and the angles to which the left front wheel 201 and the right front wheel 202 rotate are given angles θ5. Figure 6 In the given angle θ5, the direction is to the left.

[0062] In one possible implementation, the anchor wheel is the left rear wheel, and the steering direction is clockwise. A diagram illustrating the vehicle's clockwise steering around the left rear wheel can be found in [reference needed]. Figure 7 .like Figure 7 As shown, the two wheels on the non-anchor point axle are the left front wheel 201 and the right front wheel 202, and the angle to which the left front wheel 201 and the right front wheel 202 rotate is a given angle θ6. Figure 7 In the given angle θ6, the direction is a rightward deflection.

[0063] In one possible implementation, the anchor wheel is the right rear wheel, and the steering direction is counterclockwise. A diagram illustrating the vehicle's counterclockwise steering around the right rear wheel can be found in [reference needed]. Figure 8 .like Figure 8 As shown, the two wheels on the non-anchor point axle are the left front wheel 201 and the right front wheel 202, and the angle to which the left front wheel 201 and the right front wheel 202 rotate is a given angle θ7. Figure 8 In the given angle θ7, the direction is to the left.

[0064] In one possible implementation, the anchor wheel is the right rear wheel, and the steering direction is clockwise. A diagram illustrating the vehicle's counter-clockwise steering around the right rear wheel can be found in [reference needed]. Figure 9 .like Figure 9 As shown, the two wheels on the non-anchor point axle are the left front wheel 201 and the right front wheel 202, and the angle to which the left front wheel 201 and the right front wheel 202 rotate is a given angle θ8. Figure 9 In the given angle θ8, the direction is a rightward deflection.

[0065] It should be noted that, Figures 2 to 9 These are just a few exemplary illustrations provided for ease of understanding. In actual implementation, depending on the direction of the given turning angle and the direction of the torque of the wheel on the non-anchor axle, there may be other situations when the vehicle turns around the anchor axle. This embodiment does not make specific limitations on these situations.

[0066] In step 102, one of the first motor and the second motor is the front motor of the vehicle (i.e., the motor located on the front axle), and the other is the rear motor (i.e., the motor located on the rear axle). If the anchor point shaft is the front axle, then the first motor is the front motor and the second motor is the rear motor. If the anchor point shaft is the rear axle, then the first motor is the rear motor and the second motor is the front motor. This step is equivalent to determining the feedforward torque of each of the front and rear motors. The feedforward torque of the first motor is denoted as the first feedforward torque, and the feedforward torque of the second motor is denoted as the second feedforward torque.

[0067] In an exemplary embodiment, step 102 may be implemented in the following ways: S11 to S13:

[0068] S11: Determine the first slip limit torque corresponding to the anchor point axis, and determine the second slip limit torque corresponding to the non-anchor point axis.

[0069] The first slip limit torque represents the minimum torque required for the wheel on the anchor point axle to exceed its slip limit. Specifically, it can be the minimum torque output by the first motor required for the wheel on the anchor point axle to exceed its slip limit. The first slip limit torque can also be understood as the minimum torque output by the first motor required for the wheel on the anchor point axle to exceed its road surface adhesion limit.

[0070] The second slip limit torque characterizes the minimum torque required for a wheel on a non-anchored axle to exceed its slip limit. Specifically, it can be defined as the minimum torque output by the second motor required for the wheel on the non-anchored axle to exceed its slip limit. Alternatively, the second slip limit torque can be understood as the minimum torque output by the second motor required for the wheel on the non-anchored axle to exceed its road surface adhesion limit. Since the wheel on the non-anchored axle includes both the left and right wheels, the second slip limit torque here specifically characterizes the minimum torque output by the second motor required for both the left and right wheels on the non-anchored axle to exceed their slip limits.

[0071] In an exemplary embodiment, S11 may be implemented as follows: S111 to S114:

[0072] S111: Determine the first static load on the anchor point axis and the second static load on the non-anchor point axis.

[0073] The first static load on the anchor point axle can be understood as the sum of the static loads of the two wheels on the anchor point axle. The second static load on the non-anchor point axle can be understood as the sum of the static loads of the two wheels on the non-anchor point axle.

[0074] The static load of a wheel, also known as the vertical load, refers to the portion of the vehicle's weight borne by the wheels when the vehicle is stationary. In a stationary state, the vehicle's weight is distributed across all the wheels, and the weight borne by each wheel is its static load. This load is typically determined by the vehicle's unloaded weight plus the weight of passengers and cargo. Vehicle manufacturers specify the maximum static load for each wheel during the design phase to ensure the safety and durability of the tires and suspension system under normal operating conditions.

[0075] In an exemplary embodiment, the first static load F1 of the anchor point shaft and the second static load F2 of the non-anchor point shaft can be calculated using the following formula:

[0076] F1 = F z,1L +F z,1R Among them, F z,1L For the static load of the left wheel of the anchor point axle, F z,1RLet F be the static load of the right wheel on the anchor point axle. For ease of calculation, the static load of the left wheel on the anchor point axle can be considered equal to the static load of the right wheel, i.e., F. z,1R =F z,1L .

[0077] F2 = F z,2L +F z,2R Among them, F z,2L For the static load of the left wheel on the non-anchored axle, F z,2R Let F be the static load of the right wheel on the non-anchored axle. For ease of calculation, the static load of the left wheel on the non-anchored axle can be considered equal to the static load of the right wheel, i.e., F. z,2R =F z,2L .

[0078] For example, the static load of each wheel can be calculated using the following formula:

[0079]

[0080] Where m is the total vehicle mass; a is the distance between the wheel on the anchor point axle (left or right wheel) and the vehicle's center of gravity; b is the distance between the wheel on the non-anchor point axle (left or right wheel) and the vehicle's center of gravity; l is the wheelbase; and a + b = l.

[0081] S112: Obtain the first efficiency of the first motor, the second efficiency of the second motor, the first speed ratio of the first reducer located on the anchor point shaft, the second speed ratio of the second reducer located on the non-anchor point shaft, the wheel radius, and the road surface adhesion coefficient.

[0082] For ease of description in this embodiment, the motor efficiency of the first motor is denoted as the first efficiency η1, and the motor efficiency of the second motor is denoted as the second efficiency η2. Motor efficiency refers to the motor's effectiveness in converting electrical energy into mechanical energy; specifically, it is the ratio of the motor's output mechanical power to its input electrical power. The level of motor efficiency reflects the magnitude of losses during the energy conversion process. Ideally, motor efficiency can approach 100%, but in reality, due to the aforementioned losses, efficiency is always less than 100%.

[0083] Of the first reducer located on the anchor point axle and the second reducer located on the non-anchor point axle, one is the front axle reducer and the other is the rear axle reducer. The speed ratios of the front axle reducer and the rear axle reducer of a vehicle are, in most cases, fixed design values. Once the vehicle leaves the factory, these two reduction ratios are set and remain unchanged throughout the vehicle's lifespan.

[0084] In this embodiment, the speed ratio of the first reducer is denoted as the first speed ratio k1, and the speed ratio of the second reducer is denoted as the second speed ratio k2. The first speed ratio k1 refers to the transmission ratio of the gear set inside the anchor shaft, that is, the gear ratio of the reducer output from the transmission or transfer case to the anchor shaft. The second speed ratio k2 refers to the transmission ratio of the gear set inside the non-anchor shaft, that is, the gear ratio of the reducer output from the transmission or transfer case to the non-anchor shaft.

[0085] A lower gear ratio typically means higher wheel speeds and lower torque, which helps improve a vehicle's top speed and fuel economy. A higher gear ratio means lower wheel speeds and higher torque, which helps improve a vehicle's acceleration and traction.

[0086] The wheel radius is also an inherent parameter of the vehicle, fixed after the vehicle leaves the factory. The coefficient of friction is the coefficient of friction of the road surface on which the vehicle is currently located. Based on the above description, after the driver selects road surface information, the vehicle can determine the corresponding coefficient of friction based on that selected road surface information.

[0087] S113: Calculate the first slip limit torque corresponding to the anchor point shaft based on the first efficiency, first speed ratio, first static load, road surface adhesion coefficient and wheel radius.

[0088] The first slip limit torque corresponding to the anchor point shaft can be the sum of the minimum torque output by the first motor required for the left wheel of the anchor point shaft to break through the slip limit and the minimum torque output by the first motor required for the right wheel of the anchor point shaft to break through the slip limit.

[0089] For example, suppose F z,1L =F z,1R Therefore, only the static load F of the left wheel of the anchor point axle needs to be calculated. z,1L Alternatively, calculate only the static load F of the right wheel of the anchor point axle. z,1R In this case, it is equivalent to assuming that the minimum torque output of the first motor required for the left wheel of the anchor point axle to exceed its slip limit is the same as the minimum torque output of the first motor required for the right wheel of the anchor point axle to exceed its slip limit. The following calculation only considers F... z,1L Taking this as an example, the first slip limit torque F1 is calculated using the following formula:

[0090]

[0091] Where f is the road adhesion coefficient, R is the wheel radius, η1 is the first efficiency, k1 is the first speed ratio, and F z,1L The static load of the left wheel of the anchor point axle is 2*F. z,1L The first static load on the anchor point axis is τ. a This is the proportional coefficient for the torque output of the first motor. In the specific implementation, F...z,1L and F z,1R There are certain differences between them, and they may not be completely equal. Therefore, the minimum torque output of the first motor required for each wheel on both sides of the anchor point axle to overcome the slip limit may differ in practical applications. Therefore, τ is used. a Make corrections to reduce assumption F. z,1L =F z,1R In this case, the impact on the accuracy of the calculated first slip limit torque.

[0092] In this embodiment, by assuming that the static loads of the wheels on both sides of the anchor point axle are equal, it is not necessary to calculate the static loads of each wheel on both sides of the anchor point axle separately. Only the static load of either wheel on either side of the anchor point axle needs to be calculated, which facilitates the rapid calculation of the first slip limit torque. Simultaneously, the torque output proportionality coefficient τ of the first motor is used. a Further adjustments were made to ensure that the accuracy of the first slip limit torque was not significantly affected.

[0093] For example, suppose F z,1L and F z,1R If calculated independently, the first slip limit torque F1 can be calculated using the following formula:

[0094]

[0095] In this embodiment, by independently calculating the static loads of the wheels on both sides of the anchor point axle, the calculated first static load of the anchor point axle is more accurate, thereby making the calculated first slip limit torque more accurate.

[0096] S114: Calculate the second slip limit torque corresponding to the non-anchor point axle based on the second efficiency, second speed ratio, second static load, given steering angle, road adhesion coefficient and wheel radius.

[0097] The second slip limit torque corresponding to the non-anchor point axle can be the sum of the minimum torque output by the second motor required for the left wheel of the non-anchor point axle to break the slip limit and the minimum torque output by the second motor required for the right wheel of the non-anchor point axle to break the slip limit.

[0098] For example, suppose F z,2L =F z,2R Therefore, only the static load F of the left wheel on the non-anchor point axle needs to be calculated. z,2L Alternatively, calculate only the static load F of the right wheel on the non-anchor axle. z,2R In this case, it's equivalent to assuming the minimum torque output of the second motor required for the left wheel of the non-anchored axle to exceed its slip limit is the same as the minimum torque output of the second motor required for the right wheel of the non-anchored axle to exceed its slip limit. The following calculation only considers F... z,2LTaking this as an example, the second slip limit torque F2 is calculated using the following formula:

[0099]

[0100] Where f is the road adhesion coefficient, R is the wheel radius, η2 is the second efficiency, k2 is the second speed ratio, and F z,2L The static load of the left wheel on the non-anchored axle is 2*F. z,2L Let τ be the second static load on the non-anchored axle, θ be the given rotation angle of the wheel on the non-anchored axle, and τ be the second static load on the non-anchored axle. b This is the torque output proportional coefficient of the second motor. In specific implementations, F... z,2L and F z,2R There are certain differences between them, and they may not be completely equal. Therefore, the minimum torque output of the second motor required for each wheel on both sides of the non-anchor point axle to overcome the slip limit may differ in practical applications. Therefore, τ is used. b Make corrections to reduce assumption F. z,2L =F z,2R In this case, the impact on the accuracy of the calculated second slip limit torque.

[0101] In this embodiment, by assuming that the static loads of the wheels on both sides of the non-anchor point axle are equal, it is unnecessary to calculate the static loads of each wheel on both sides of the non-anchor point axle separately. Only the static load of either wheel on either side of the non-anchor point axle needs to be calculated, which facilitates the rapid calculation of the second slip limit torque. Simultaneously, the torque output proportionality coefficient τ of the second motor is used. b Further adjustments were made to ensure that the accuracy of the second slip limit torque was not significantly affected.

[0102] For example, suppose F z,2L and F z,2R If calculated independently, the second slip limit torque F2 can be calculated using the following formula:

[0103]

[0104] In this embodiment, by independently calculating the static loads of the wheels on both sides of the non-anchor point axle, the calculated second static load of the non-anchor point axle is more accurate, thereby making the calculated second slip limit torque more accurate.

[0105] S12: Determine the first feedforward torque of the first motor based on the first slip limit torque; wherein the first feedforward torque is less than or equal to the first slip limit torque.

[0106] Specifically, let's assume the first feedforward torque is denoted as T. a Then T a≤F1, meaning that after determining the first slip limit torque F1, a value less than or equal to F1 can be selected as the first feedforward torque T. a This is to ensure that the non-anchor wheel of the anchor point axis does not exceed the slip limit as much as possible.

[0107] S13: Determine the second feedforward torque of the second motor based on the second slip limit torque; wherein the second feedforward torque is greater than or equal to the second slip limit torque.

[0108] Specifically, let's assume the second feedforward torque is denoted as T. b Then T b ≥F2, meaning that after determining the second slip limit torque F2, a value greater than or equal to F2 can be selected as the second feedforward torque T. b This is to ensure that the wheels on the non-anchor axle exceed the slip limit as much as possible.

[0109] In this embodiment, by setting the feedforward torque of the second motor on the non-anchor point axle to be greater than or equal to the second slip limit torque, it is ensured that the wheels on the non-anchor point axle can generate sufficient lateral force to propel the vehicle around the anchor point wheel. By setting the feedforward torque of the first motor on the anchor point axle to be less than or equal to the first slip limit torque, it is ensured that the non-anchor point wheels on the anchor point axle do not exceed the slip limit as much as possible. Since the anchor point wheel needs to remain relatively stationary to act as a steering fulcrum, if the non-anchor point wheels on the anchor point axle also exceed the slip limit, it will cause the vehicle's steering control to become unstable, potentially leading to loss of vehicle control and reducing steering accuracy and safety. Therefore, by setting the second feedforward torque of the second motor to be greater than or equal to the second slip limit torque, and the first feedforward torque of the first motor to be less than or equal to the first slip limit torque, it is beneficial to improve steering accuracy and safety while achieving steering around the anchor point wheel.

[0110] In step 103: torque feedback control is performed on the first motor to obtain the first corrected torque of the first motor, and torque feedback control is performed on the second motor to obtain the second corrected torque of the second motor.

[0111] Specifically, to improve the performance and stability of the steering function, this embodiment also incorporates feedback control during the control process. By applying torque feedback control to both the first and second motors, it is beneficial to achieve precise torque control.

[0112] In an exemplary embodiment, the above-described method for performing torque feedback control on the first motor to obtain the first corrected torque of the first motor includes the following steps S21 to S23:

[0113] S21: Obtain the actual wheel speed and target wheel speed of the non-anchor wheel on the anchor point axle.

[0114] It is understandable that the anchor point axle includes a left wheel and a right wheel. When the left wheel on the anchor point axle is an anchor point wheel, the right wheel on the anchor point axle is a non-anchor point wheel; when the right wheel on the anchor point axle is an anchor point wheel, the left wheel on the anchor point axle is a non-anchor point wheel.

[0115] For example, in Figure 2 In the diagram, if the anchor point wheel is the left front wheel, then the non-anchor point wheel on the anchor point axle is the right front wheel. Figure 4 In the diagram, if the anchor point wheel is the right front wheel, then the non-anchor point wheel on the anchor point axle is the left front wheel. Figure 6 In the diagram, if the anchor point wheel is the left rear wheel, then the non-anchor point wheel on the anchor point axle is the right rear wheel. Figure 8 In the diagram, if the anchor point wheel is the right rear wheel, then the non-anchor point wheel on the anchor point axle is the left rear wheel.

[0116] Specifically, the actual wheel speed of the non-anchor wheel on the anchor axle can be monitored by a wheel speed sensor located at or near the hub of the non-anchor wheel. The target wheel speed of the non-anchor wheel on the anchor axle is the desired wheel speed that the non-anchor wheel will achieve.

[0117] In an exemplary embodiment, the target wheel speed ω of the non-anchor wheel on the aforementioned anchor point axle is... ‘ m The target wheel speed ω is determined as follows: The vehicle's current actual yaw rate (Yaw), wheelbase (B), and target wheel speed sign coefficient (ξ) are obtained. The product of the actual yaw rate (Yaw), wheelbase (B), and target wheel speed sign coefficient (ξ) is then used as the target wheel speed ω. ‘ m In other words, the target wheel speed is calculated using the following formula:

[0118] ω ‘ m =Yaw*B*ξ

[0119] Here, track width B refers to the horizontal distance between the center points of two wheels on the same axle of the vehicle. Track width is divided into front track width and rear track width, corresponding to the distance between the wheels on the front axle and the rear axle, respectively. In the above formula, track width B is the distance between the wheels on the anchor point axle. The target wheel speed sign coefficient is determined based on the vehicle's steering direction and the position of the wheels (left or right), and is used to adjust the directionality of the target wheel speed.

[0120] In this embodiment, the target wheel speed is the product of the vehicle's actual yaw rate, track width, and the sign coefficient of the target wheel speed. This helps ensure that non-anchor wheels on the anchor axle can achieve pure rolling during steering, avoiding slippage and thus improving vehicle handling and stability. Pure rolling of non-anchor wheels on the anchor axle means that the non-anchor wheel does not slide forward or backward when in contact with the ground. In pure rolling mode, the friction between the tire and the ground is maximized, resulting in more precise steering response, more stable handling, and reduced abnormal tire wear, thus improving driving safety.

[0121] S22: Obtain the actual longitudinal resultant force and the target longitudinal resultant force of the vehicle.

[0122] The actual longitudinal resultant force of the vehicle is the sum of all longitudinal forces acting on it. For example, this actual longitudinal resultant force = longitudinal force of the anchor point axis + longitudinal force of the non-anchor point axis + longitudinal component of centrifugal force. To ensure no longitudinal displacement of the vehicle, the target longitudinal resultant force in this embodiment approaches 0; ideally, the target longitudinal resultant force is equal to 0.

[0123] S23: Perform PID control on the first difference between the actual wheel speed and the target wheel speed, or perform PID control on the second difference between the actual longitudinal resultant force and the target longitudinal resultant force, to obtain the first corrected torque of the first motor.

[0124] Specifically, PID (Proportional Integral Derivative) control is applied to the first difference between the actual wheel speed and the target wheel speed. That is, when the first motor is subjected to torque feedback control, the wheel speed is used as the main control target for feedback control, so that the actual wheel speed approaches the target wheel speed.

[0125] In some embodiments, the first difference is used as the input to the PID controller, and the output of the PID controller can be directly used as the first corrected torque of the first motor.

[0126] In some embodiments, a schematic diagram illustrating the principle of PID control of the first difference can be found in [reference needed]. Figure 10 . Figure 10 In the process, the first difference between the target wheel speed and the actual wheel speed of the non-anchor wheel on the anchor point axle is used as the input of the PID controller. The output of the PID controller is the first initial correction torque Tc1 of the first motor. The product of the first initial correction torque Tc1 of the first motor and the anchor point axle feedback torque correction coefficient C1 based on the wheel speed is the final first correction torque of the first motor. C1 is used to adjust the first initial correction torque Tc1 of the PID controller output to adapt to specific vehicle dynamics and control requirements. C1 can be used to amplify or reduce the PID controller output to ensure the first correction torque... Within a safe and effective range. The anchor point axle feedback torque correction coefficient C1, based on wheel speed, can be pre-calibrated, for example, based on vehicle operating data and environmental data, so that the first correction torque after C1 correction can adapt to the vehicle's current operating data and environmental data.

[0127] The above-mentioned PID control of the second difference between the actual longitudinal resultant force and the target longitudinal resultant force, that is, when the torque feedback control of the first motor is performed, the longitudinal resultant force is the main control target, so as to make the actual longitudinal resultant force approach the target longitudinal resultant force.

[0128] In some embodiments, the second difference is used as the input to the PID controller, and the output of the PID controller can be directly used as the first corrected torque of the first motor.

[0129] In this embodiment, to ensure that the vehicle has no longitudinal displacement, the torque of the non-anchor wheel on the anchor point shaft is controlled to make the actual longitudinal resultant force of the whole vehicle approach 0 as much as possible. When the absolute value of the actual longitudinal resultant force is greater than the target longitudinal resultant force, PID control is performed based on the difference between the actual longitudinal resultant force and the target longitudinal resultant force. The torque of the first motor on the anchor point shaft is corrected to make the actual longitudinal resultant force approach zero.

[0130] In some embodiments, a schematic diagram illustrating the principle of PID control of the second difference can be found in [reference needed]. Figure 11 . Figure 11 In this process, the longitudinal force of the anchor point axis, the longitudinal force of the non-anchor point axis, and the longitudinal component of the centrifugal force are summed to obtain the actual longitudinal resultant force. The second difference between the actual longitudinal resultant force and the target longitudinal resultant force is used as the input of the PID controller. The output of the PID controller is the first initial correction torque Tc1 of the first motor. The product of the first initial correction torque Tc1 of the first motor and the anchor point axis feedback torque correction coefficient C2 based on the longitudinal resultant force is the final first correction torque of the first motor. C2 is used to adjust the first initial correction torque Tc1 of the PID control output to adapt to specific vehicle dynamics and control requirements. C2 can be used to amplify or reduce the PID controller output to ensure the first correction torque... Within a safe and effective range. Among them, the anchor shaft feedback torque correction coefficient C2 based on the longitudinal resultant force can be pre-calibrated, for example, based on the vehicle's operating condition data and the environmental data, so that the first correction torque after C2 correction can adapt to the vehicle's current operating condition data and environmental data.

[0131] As described above, the feedback control of the first motor on the anchor point shaft in this embodiment includes two feedback control methods. One method uses wheel speed as the primary control target, while the other uses longitudinal resultant force as the primary control target. To avoid conflict between these two feedback control methods, this embodiment integrates them, preventing both from operating simultaneously. Under different circumstances, either longitudinal resultant force or wheel speed is selected as the primary control target for feedback control, thus avoiding conflict between the two methods.

[0132] In an exemplary embodiment, the above-described S23 is implemented as follows: S231 to S232:

[0133] S231: When the actual wheel speed is within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, PID control is applied to the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the first corrected torque of the first motor.

[0134] S232: When the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is within the set resultant force range, PID control is applied to the first difference between the actual wheel speed and the target wheel speed to obtain the first corrected torque of the first motor.

[0135] The wheel speed range can be set based on the target wheel speed to measure whether the current actual wheel speed is close to the target wheel speed. The resultant force range can be set based on the target longitudinal resultant force to measure whether the current actual longitudinal resultant force is close to the target longitudinal resultant force. If the target wheel speed is denoted as ω... ‘ m The wheel speed range can then be set as follows: [ω] ‘ m -ω ‘ m *y1, ω ‘ m +ω ‘ m *y1], where y1 can take a value between 10% and 20%, and this embodiment does not specifically limit it. If the target longitudinal resultant force is denoted as F3, the resultant force range can be set as the following resultant force interval [F3-F3*y2, F3+F3*y2], where y2 can take a value between 10% and 20%, and this embodiment does not specifically limit it.

[0136] When the actual wheel speed is within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, it indicates that the current actual wheel speed is close to the target wheel speed, the non-anchor wheel of the anchor point axle has not yet exceeded the slip limit, and the current actual longitudinal resultant force is not close to the target longitudinal resultant force. Therefore, the actual wheel speed does not require further adjustment, while the actual longitudinal resultant force needs further adjustment. Thus, in this case, wheel speed is not the primary control target; instead, the longitudinal resultant force is the primary control target to achieve longitudinal force balance. That is, PID control is applied to the second difference between the actual and target longitudinal resultant forces to obtain the first correction torque of the first motor, ensuring the stability of the vehicle's point-to-point steering function.

[0137] When the actual wheel speed is not within the set wheel speed range but the actual longitudinal resultant force is within the set resultant force range, it indicates that the current actual longitudinal resultant force is close to the target longitudinal resultant force, while the actual wheel speed is not close to the target wheel speed. This means the non-anchor wheel on the anchor point axle has exceeded its slip limit. Therefore, wheel speed should be the primary control target at this point, and the actual longitudinal resultant force does not need adjustment. Thus, in this situation, instead of using longitudinal resultant force as the primary control target, wheel speed should be the primary control target to adjust the actual wheel speed to the set wheel speed range. This involves using PID control on the second difference between the actual and target longitudinal resultant forces to obtain the first correction torque of the first motor. This ensures the stability of the vehicle's steering function around the anchor point wheels while minimizing tire wear.

[0138] When the actual wheel speed is within the set wheel speed range and the actual longitudinal resultant force is within the set resultant force range, it means that the current actual longitudinal resultant force is close to the target longitudinal resultant force and the actual wheel speed is also close to the target wheel speed. This means that there is no need to further adjust the wheel speed and longitudinal resultant force. In other words, there is no need to perform feedback torque control on the first motor. Or, even if torque feedback control is performed on the first motor, the first corrected torque of the first motor is basically close to or about 0.

[0139] In an exemplary embodiment, when the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, the vehicle is controlled to stop steering and the vehicle is braked.

[0140] Specifically, when both the actual wheel speed and the actual longitudinal resultant force are outside the set wheel speed range, it indicates that the current actual longitudinal resultant force is not close to the target longitudinal resultant force, and the actual wheel speed is also not close to the target wheel speed. In this case, it is difficult to use feedback control to make the actual longitudinal resultant force approach the target longitudinal resultant force while simultaneously making the actual wheel speed approach the target wheel speed. Therefore, in this situation, the vehicle is controlled to stop steering, that is, the anchor point steering function is disengaged, and the vehicle is braked to ensure vehicle safety.

[0141] In an exemplary embodiment, the above-described torque feedback control of the second motor to obtain the second corrected torque of the second motor includes the following steps S31 to S32:

[0142] S31: Obtain the average actual wheel speed and the average target wheel speed of the left and right wheels on the non-anchor point axle.

[0143] S32: Perform PID control on the third difference between the actual average wheel speed and the target average wheel speed to obtain the second corrected torque of the second motor.

[0144] The target wheel speed average value can be pre-calibrated, for example, based on different road surface information and different vehicle condition data, so that the determined target wheel speed average value can adapt to the current road surface information and vehicle condition data.

[0145] In some embodiments, the third difference is used as the input to the PID controller, and the output of the PID controller can be directly used as the second corrected torque of the second motor.

[0146] In some embodiments, a schematic diagram illustrating the principle of PID control of the third difference can be found in [reference needed]. Figure 12 . Figure 12 In the process, the actual wheel speeds of the left wheel on the non-anchor axle and the right wheel on the non-anchor axle are summed to obtain the total actual wheel speed. Then, the total actual wheel speed is multiplied by 0.5 to obtain the average actual wheel speed. The third difference between the target average wheel speed and the actual average wheel speed is used as the input to the PID controller. The output of the PID controller is the second initial correction torque Tc2 of the second motor. The product of the second initial correction torque Tc2 of the second motor and the non-anchor axle feedback torque correction coefficient C3 based on wheel speed is the final second correction torque of the second motor. C3 is used to adjust the second initial correction torque Tc2 of the PID control output to adapt to specific vehicle dynamics and control requirements. C3 can be used to amplify or reduce the PID controller output to ensure the second correction torque... Within a safe and effective range. Among them, the non-anchor point axle feedback torque correction coefficient C3 based on wheel speed can be pre-calibrated, for example, based on the vehicle's operating condition data and the environmental data, so that the second correction torque after correction by C3 can adapt to the vehicle's current operating condition data and environmental data.

[0147] In step 104, the first feedforward torque and the first correction torque are added together to obtain the first target torque of the first motor, and the second feedforward torque and the second correction torque are added together to obtain the second target torque of the second motor.

[0148] In step 105, braking force is applied to the anchor wheel to cause it to lock up. In practice, this braking force can be applied to the anchor wheel through the independent braking control function of an electronic stability control system or an anti-lock braking system.

[0149] Optionally, braking force can be gradually increased on the anchor wheel until its rotational speed is significantly reduced, approaching a stop, to avoid excessive braking that could lead to loss of vehicle control. During the application of braking force to the anchor wheel, wheel speed sensors monitor its rotational speed; once the wheel speed drops to near zero, it indicates that the anchor wheel is about to lock up. Once the anchor wheel locks up, the current braking force is maintained to ensure that the anchor wheel remains braked during vehicle steering.

[0150] After determining a given turning angle, the two wheels on the non-anchor axle are controlled to rotate according to the given turning angle, so that the two wheels on the non-anchor axle rotate to the given angle.

[0151] In practical implementation, the two control actions—applying braking force to the anchor wheel and controlling the rotation of the two wheels on the non-anchor wheel axle according to a given rotation angle—can be executed sequentially or simultaneously according to a preset execution order. For example, braking force can be applied to the anchor wheel first, and after the anchor wheel is in a braking state, the two wheels on the non-anchor wheel axle can be controlled to rotate according to the given rotation angle. Alternatively, the two wheels on the non-anchor wheel axle can be controlled to rotate according to the given rotation angle first, and after the two wheels on the non-anchor wheel axle have rotated to a given angle, braking force can be applied to the anchor wheel. Or, while applying braking force to the anchor wheel, the two wheels on the non-anchor wheel axle can be controlled to rotate according to the given rotation angle simultaneously to accelerate the control speed.

[0152] In step 106, when the anchor wheel is in a braking state and the wheels on the non-anchor axle rotate to a given angle, the first motor is controlled to output a first target torque, and the second motor is controlled to output a second target torque, so that the vehicle turns around the anchor wheel in the aforementioned steering direction.

[0153] During the vehicle's steering process around the anchor point wheels in the aforementioned steering direction, the vehicle's position can be monitored in real time. When the vehicle reaches the target position selected by the driver, the output of the first and second motors is reduced to 0, and the vehicle is stably parked at the target position. Once the vehicle is parked at the target position, the anchor point steering function is disengaged, the wheels on the non-anchor point axles are returned to center, and the braking force on the anchor point wheels is released.

[0154] To further facilitate understanding of the embodiments of this application, the following description is provided in conjunction with... Figure 13 The steering control method in the embodiments of this application will be further described. Figure 13 This is a schematic diagram of a steering control method provided in an embodiment of this application.

[0155] For example, such as Figure 13 As shown, this control method consists of two parts: feedforward control and feedback control. The feedforward control and feedback control are described below:

[0156] In feedforward control, the given steering angle of the wheels on the non-anchor axle is determined based on the anchor wheel selected by the driver and the steering direction. The braking torque of the anchor wheel, the initial torque of the anchor axle motor, and the initial torque of the non-anchor axle motor are also determined. The anchor axle motor is the first motor on the anchor axle mentioned above, and its initial torque is the first feedforward torque. The non-anchor axle motor is the second motor on the non-anchor axle mentioned above, and its initial torque is the second feedforward torque. The braking torque is the product of the braking force applied to the anchor wheel and the lever arm (wheel radius). Feedback control is further divided into feedback control of the non-anchor axle motor and feedback control of the anchor axle motor.

[0157] Feedback control of non-anchor axle motors primarily relies on wheel speed-based feedback control. Wheel speed-based feedback control can be understood as follows: PID control is performed based on the actual average wheel speed of the left and right wheels on the non-anchor axle and the target average wheel speed to obtain the torque correction value for the non-anchor axle motor. This torque correction value is the second correction torque of the second motor mentioned above.

[0158] The feedback control of the anchor shaft motor integrates anchor shaft feedback control based on longitudinal resultant force and anchor shaft feedback control based on wheel speed.

[0159] Anchor point axle feedback control based on wheel speed can be understood as follows: PID control is applied to the first difference between the actual wheel speed and the target wheel speed of the non-anchor point wheels on the anchor point axle to obtain the torque correction value of the anchor point axle motor. Anchor point axle feedback control based on longitudinal resultant force can be understood as follows: PID control is applied to the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the torque correction value of the anchor point axle motor. The torque correction value of the anchor point axle motor is the first correction torque of the first motor mentioned above. Figure 13 Fusion control in this context refers to selecting either longitudinal resultant force or wheel speed as the primary control objective for feedback control under different conditions, in order to avoid conflicts between the two feedback control methods.

[0160] After obtaining the initial torque of the anchor-axis motor, the initial torque of the non-anchor-axis motor, the torque correction value of the anchor-axis motor, and the torque correction value of the non-anchor-axis motor, the initial torque of the anchor-axis motor and its torque correction value are added together to obtain the target torque of the anchor-axis. The initial torque of the non-anchor-axis motor is then added together with its torque correction value to obtain the target torque of the non-anchor-axis. This target torque of the anchor-axis is the first target torque of the first motor mentioned above, and the target torque of the non-anchor-axis is the second target torque of the second motor mentioned above.

[0161] In this embodiment, using the anchor point steering function, the driver can select the anchor point wheel and steering direction to determine a given angle for the non-anchor point wheel. Based on this given angle, the wheel on the non-anchor point axle is controlled to rotate to the given angle without the driver turning the steering wheel. Once the wheel on the non-anchor point axle has rotated to the given angle, braking force is applied to the selected anchor point wheel to lock it up. Through feedforward control of the anchor point axle motor and the non-anchor point axle motor, combined with feedback control to adjust the torque output of the anchor point axle motor and the non-anchor point axle motor, the force on the entire vehicle approaches balance. The vehicle's lateral and longitudinal speeds are fixed, and the vehicle's yaw rate is a fixed value, enabling the vehicle to steer around the anchor point wheel. This assists the driver in entering and exiting tight side parking spaces and in making U-turns on narrow roads.

[0162] The steering control method of this application embodiment is described below from the user's perspective:

[0163] Step 1: The driver actively activates the vehicle's anchor point steering function via a function switch.

[0164] Step two: Following the prompts on the central control screen, the driver selects the anchor wheel, steering direction, road surface information (dry or wet asphalt road, dry or wet cement road, dirt road, etc.), and target location.

[0165] Step three: When the vehicle determines that its current state meets the preset conditions for activating the anchor point steering function, the driver presses the start steering button, releases the steering wheel and brake pedal, and the wheels on the non-anchor point axles automatically rotate to a given angle according to the steering direction. Braking force is applied to the anchor point wheels to lock them, the anchor point axle motor outputs the first target torque, and the non-anchor point axle motors output the second target torque, and the vehicle begins to steer. The preset conditions are set according to actual needs and characterize whether it is safe for the vehicle to perform the anchor point steering function in the current state. When the preset conditions are met, the safe execution of the anchor point steering function can be ensured.

[0166] Step four: When approaching the target position set by the driver, the output torque of the anchor point axle motor and the non-anchor point axle motor actively decreases to 0. The driver presses the brake pedal, and the vehicle comes to a stable stop at the target position. The anchor point steering function actively disengages, the non-anchor point axle wheels return to center, and the braking force of the anchor point wheels is released.

[0167] In this embodiment, the four-wheel steering and four-wheel drive functions are fully utilized. A combination of feedforward and feedback control, along with PID control, is used to regulate the vehicle's motor torque, ensuring the vehicle's posture and precision when steering around the anchor point wheels. On one hand, this enhances the vehicle's agility, reduces the difficulty of handling, and improves the sense of luxury and ease of operation. On the other hand, this function increases driving safety, preventing unnecessary collisions, and can also alleviate traffic congestion to some extent. Therefore, the steering control method in this embodiment can enhance the driver's driving pleasure and ease driving anxiety.

[0168] Figure 14 This is a schematic diagram of the structure of a vehicle steering control device provided in an embodiment of this application.

[0169] For example, such as Figure 14 As shown, the steering control device 300 includes:

[0170] The first determining module 301 is used to determine the anchor wheel, the steering direction, and the given turning angle of the wheels on the non-anchor wheel of the vehicle; wherein, the axle where the anchor wheel is located is the anchor wheel axle, and the non-anchor wheel axle is any axle on the vehicle other than the anchor wheel axle.

[0171] The feedforward torque determination module 302 is used to determine the first feedforward torque of the first motor on the anchor point shaft and the second feedforward torque of the second motor on the non-anchor point shaft.

[0172] The feedback control module 303 is used to perform torque feedback control on the first motor to obtain a first corrected torque of the first motor, and to perform torque feedback control on the second motor to obtain a second corrected torque of the second motor.

[0173] The second determining module 304 is used to determine the first target torque of the first motor based on the first feedforward torque and the first correction torque, and to determine the second target torque of the second motor based on the second feedforward torque and the second correction torque.

[0174] The first control module 305 is used to control the braking of the anchor point wheel and, according to the given turning angle, control the rotation of the wheel on the non-anchor point axle.

[0175] The second control module 306 is used to control the first motor to output the first target torque and the second motor to output the second target torque when the anchor wheel is in a braking state and the wheel on the non-anchor wheel rotates to the given angle, so that the vehicle turns around the anchor wheel in the steering direction.

[0176] In some implementations, the feedforward torque determination module 302 includes: a slip limit torque determination unit, configured to determine a first slip limit torque corresponding to the anchor point shaft and a second slip limit torque corresponding to the non-anchor point shaft; wherein the first slip limit torque represents the minimum torque required for the wheel on the anchor point shaft to exceed the slip limit; and the second slip limit torque represents the minimum torque required for the wheel on the non-anchor point shaft to exceed the slip limit; a first feedforward torque determination unit, configured to determine a first feedforward torque of the first motor based on the first slip limit torque; wherein the first feedforward torque is less than or equal to the first slip limit torque; and a second feedforward torque determination unit, configured to determine a second feedforward torque of the second motor based on the second slip limit torque; wherein the second feedforward torque is greater than or equal to the second slip limit torque.

[0177] In some implementations, the slip limit torque determining unit is specifically used to determine the first static load of the anchor point shaft and the second static load of the non-anchor point shaft; obtain the first efficiency of the first motor, the second efficiency of the second motor, the first speed ratio of the first reducer located on the anchor point shaft, the second speed ratio of the second reducer located on the non-anchor point shaft, the wheel radius, and the road surface adhesion coefficient; calculate the first slip limit torque corresponding to the anchor point shaft based on the first efficiency, the first speed ratio, the first static load, the road surface adhesion coefficient, and the wheel radius; and calculate the second slip limit torque corresponding to the non-anchor point shaft based on the second efficiency, the second speed ratio, the second static load, the given rotation angle, the road surface adhesion coefficient, and the wheel radius.

[0178] In some implementations, the feedback control module 303 includes: a first acquisition unit for acquiring the actual wheel speed and target wheel speed of the non-anchor wheel on the anchor point axle; a second acquisition unit for acquiring the actual longitudinal resultant force and target longitudinal resultant force of the vehicle; and a first PID control unit for performing PID control on a first difference between the actual wheel speed and the target wheel speed, or performing PID control on a second difference between the actual longitudinal resultant force and the target longitudinal resultant force, to obtain a first correction torque of the first motor.

[0179] In some implementations, the first PID control unit is specifically configured to: when the actual wheel speed is within a set wheel speed range and the actual longitudinal resultant force is not within a set resultant force range, perform PID control on a second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain a first corrected torque of the first motor; and when the actual wheel speed is not within a set wheel speed range and the actual longitudinal resultant force is within a set resultant force range, perform PID control on a first difference between the actual wheel speed and the target wheel speed to obtain a first corrected torque of the first motor.

[0180] In some implementations, the steering control device further includes a third control module, used to control the vehicle to stop steering and to brake the vehicle when the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range.

[0181] In some implementations, the first acquisition unit is specifically used to acquire the vehicle's current actual yaw rate, wheel track, and target wheel speed sign coefficient; and to use the product of the actual yaw rate, the wheel track, and the target wheel speed sign coefficient as the target wheel speed.

[0182] In some implementations, the feedback control module 303 includes: a third acquisition unit, used to acquire the actual average wheel speed and the target average wheel speed of the left and right wheels on the non-anchor point axle; and a second PID control unit, used to perform PID control on the third difference between the actual average wheel speed and the target average wheel speed to obtain the second corrected torque of the second motor.

[0183] Figure 15 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0184] For example, such as Figure 15 As shown, the vehicle 400 includes a memory 401 and a processor 402, wherein the memory 401 stores executable program code 4011, and the processor 402 is used to call and execute the executable program code 4011 to perform a vehicle steering control method.

[0185] Furthermore, this application also protects an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a vehicle steering control method provided in this application.

[0186] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0187] When each functional module is divided according to its corresponding function, the device may further include a first determining module, a feedforward torque determining module, a feedback control module, a second determining module, a first control module, and a second control module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0188] It should be understood that the device provided in this embodiment is used to execute the above-described vehicle steering control method, and therefore can achieve the same effect as the above-described implementation method.

[0189] When using an integrated unit, the device may include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the vehicle's movements. The storage module can be used to support the vehicle in executing relevant program code.

[0190] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0191] In addition, the device provided in the embodiments of this application may specifically be a chip, component or module. The chip may include a connected processor and a memory. The memory is used to store instructions. When the processor calls and executes the instructions, the chip can execute a vehicle steering control method provided in the above embodiments.

[0192] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement a vehicle steering control method provided in the above embodiment.

[0193] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to implement a vehicle steering control method provided in the above embodiment.

[0194] In this embodiment, the device, computer-readable storage medium, computer program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0195] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0196] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0197] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A vehicle steering control method, characterized in that, The method includes: Determine the anchor wheel, steering direction, and given angle of the wheels on the non-anchor wheel of the vehicle; wherein, the axle where the anchor wheel is located is the anchor wheel axle, and the non-anchor wheel axle is any axle on the vehicle other than the anchor wheel axle. Determine the first feedforward torque of the first motor on the anchor point axis, and determine the second feedforward torque of the second motor on the non-anchor point axis; The first motor is subjected to torque feedback control to obtain a first corrected torque, and the second motor is subjected to torque feedback control to obtain a second corrected torque. Based on the first feedforward torque and the first correction torque, a first target torque of the first motor is determined, and based on the second feedforward torque and the second correction torque, a second target torque of the second motor is determined. Control the braking of the anchor point wheel, and control the rotation of the wheel on the non-anchor point axle according to the given turning angle; When the anchor wheel is in a braking state and the wheel on the non-anchor axle rotates to the given turning angle, the first motor is controlled to output the first target torque and the second motor is controlled to output the second target torque so that the vehicle turns around the anchor wheel in the steering direction. Wherein, the step of performing torque feedback control on the first motor to obtain the first corrected torque of the first motor includes: Obtain the actual wheel speed and target wheel speed of the non-anchor wheel on the anchor point axle; Obtain the actual longitudinal resultant force and the target longitudinal resultant force of the vehicle; When the actual wheel speed is within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, PID control is applied to the second difference between the actual longitudinal resultant force and the target longitudinal resultant force to obtain the first corrected torque of the first motor. When the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is within the set resultant force range, PID control is applied to the first difference between the actual wheel speed and the target wheel speed to obtain the first corrected torque of the first motor.

2. The method according to claim 1, characterized in that, Determining the first feedforward torque of the first motor on the anchor point shaft and the second feedforward torque of the second motor on the non-anchor point shaft includes: A first slip limit torque corresponding to the anchor point shaft is determined, and a second slip limit torque corresponding to the non-anchor point shaft is determined; wherein, the first slip limit torque represents the minimum torque required for the wheel on the anchor point shaft to exceed the slip limit; and the second slip limit torque represents the minimum torque required for the wheel on the non-anchor point shaft to exceed the slip limit. The first feedforward torque of the first motor is determined based on the first slip limit torque; wherein the first feedforward torque is less than or equal to the first slip limit torque; The second feedforward torque of the second motor is determined based on the second slip limit torque; wherein the second feedforward torque is greater than or equal to the second slip limit torque.

3. The method according to claim 2, characterized in that, Determining the first slip limit torque corresponding to the anchor point axis and determining the second slip limit torque corresponding to the non-anchor point axis includes: Determine the first static load on the anchor point axis and the second static load on the non-anchor point axis; The first efficiency of the first motor, the second efficiency of the second motor, the first speed ratio of the first reducer located on the anchor point shaft, the second speed ratio of the second reducer located on the non-anchor point shaft, the wheel radius, and the road surface adhesion coefficient are obtained. Calculate the first slip limit torque corresponding to the anchor point shaft based on the first efficiency, the first speed ratio, the first static load, the road surface adhesion coefficient, and the wheel radius; The second slip limit torque corresponding to the non-anchor point shaft is calculated based on the second efficiency, the second speed ratio, the second static load, the given turning angle, the road surface adhesion coefficient, and the wheel radius.

4. The method according to claim 1, characterized in that, The method further includes: If the actual wheel speed is not within the set wheel speed range and the actual longitudinal resultant force is not within the set resultant force range, control the vehicle to stop steering and apply braking control to the vehicle.

5. The method according to claim 1, characterized in that, The target wheel speed of the non-anchor wheel on the anchor point axle is determined in the following way: Obtain the vehicle's current actual yaw rate, wheel track, and target wheel speed sign coefficient; The target wheel speed is the product of the actual yaw rate, the wheel track, and the sign coefficient of the target wheel speed.

6. The method according to claim 1, characterized in that, The step of performing torque feedback control on the second motor to obtain the second corrected torque of the second motor includes: Obtain the average actual wheel speed and the average target wheel speed of the left and right wheels on the non-anchor point axle; The third difference between the actual average wheel speed and the target average wheel speed is subjected to PID control to obtain the second corrected torque of the second motor.

7. A vehicle steering control device, characterized in that, The steering control device includes: The first determining module is used to determine the anchor wheel, the steering direction, and the given turning angle of the wheels on the non-anchor wheel of the vehicle; wherein, the axle where the anchor wheel is located is the anchor wheel axle, and the non-anchor wheel axle is any axle on the vehicle other than the anchor wheel axle. A feedforward torque determination module is used to determine the first feedforward torque of the first motor on the anchor point shaft and the second feedforward torque of the second motor on the non-anchor point shaft. The feedback control module is used to perform torque feedback control on the first motor to obtain a first corrected torque of the first motor, and to perform torque feedback control on the second motor to obtain a second corrected torque of the second motor. The second determining module is used to determine the first target torque of the first motor based on the first feedforward torque and the first correction torque, and to determine the second target torque of the second motor based on the second feedforward torque and the second correction torque. The first control module is used to control the braking of the anchor point wheel and, according to the given turning angle, control the rotation of the wheel on the non-anchor point axle. The second control module is used to control the first motor to output the first target torque and the second motor to output the second target torque when the anchor wheel is in a braking state and the wheel on the non-anchor axle rotates to the given angle, so that the vehicle turns around the anchor wheel in the steering direction. The feedback control module includes: The first acquisition unit is used to acquire the actual wheel speed and target wheel speed of the non-anchor wheel on the anchor point axle; The second acquisition unit is used to acquire the actual longitudinal resultant force and the target longitudinal resultant force of the vehicle. A first PID control unit is configured to perform PID control on a second difference between the actual longitudinal resultant force and the target longitudinal resultant force when the actual wheel speed is within a set wheel speed range and the actual longitudinal resultant force is not within a set resultant force range, thereby obtaining a first corrected torque of the first motor; and to perform PID control on a first difference between the actual wheel speed and the target wheel speed when the actual wheel speed is not within a set wheel speed range and the actual longitudinal resultant force is within a set resultant force range, thereby obtaining a first corrected torque of the first motor.

8. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 6.

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