Drive-by-wire four-wheel steering system and optimal control method

Abstract

The invention relates to the technical field of vehicle steering, in particular to a drive-by-wire four-wheel steering system and an optimal control method. The system comprises a steering wheel assembly, a front wheel assembly, a rear wheel assembly and a main controller, the steering wheel assembly comprises a steering wheel, a rotating rod and an aligning motor, the rotating rod is connected to the center of the lower portion of the steering wheel, the lower end of the rotating rod is connected with the aligning motor, and a rotating speed sensor is arranged on the steering wheel; the front wheel assembly comprises two front wheels, and the rear wheel assembly comprises two rear wheels. The front wheels and the rear wheels are driven by a steering motor, and rotating speed sensors are arranged on the front wheels and the rear wheels; a rotating speed sensor arranged on the steering wheel, rotating speed sensors arranged on the front wheels and the rear wheels, the steering motor and the aligning motor are all electrically connected with a main controller. And the safety and the optimization precision are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering, and in particular to a wire-controlled four-wheel steering system and an optimization control method. Background Art

[0002] An automotive steer-by-wire system consists of three main components: the steering wheel assembly, the steering actuator assembly, and the main control unit (ECU), along with auxiliary systems such as a fail-safe system and a power supply. The automotive steering system is a key component in determining a vehicle's active safety. Traditional automotive steering systems are mechanical systems, where the driver operates the steering wheel, which is then transmitted to the steering wheels via a steering gear and a series of levers. However, the automotive steer-by-wire system eliminates the mechanical connection between the steering wheel and the steering wheels, achieving steering entirely through electrical energy, thus eliminating the limitations of traditional steering systems.

[0003] Chinese patent CN106891992A discloses a compound steering system and a multi-objective optimization method thereof. The compound steering system integrates an electric power steering system and a wire-controlled four-wheel steering system, and adopts a power-assisted motor and four wheel hub motors for steering assistance. An electric power steering system is added to the wire-controlled four-wheel steering system, and there is a mechanical connection, which can ensure the reliability of the steering system. Due to the complex structure of the compound steering system, a multi-objective optimization method is proposed based on the compound steering system. Part of the steering system structural parameters are used as optimization variables, an objective function is established, constraints are set, and an optimization model of the compound steering system is established. A simulated annealing algorithm is used to perform multi-objective optimization on the compound steering system. However, in the optimization method of the above-mentioned compound steering system, the influence of the pressure on the wheel on the vehicle safety is not considered, and the optimization accuracy needs to be improved.

[0004] Therefore, there is an urgent need to provide a wire-controlled four-wheel steering system and an optimized control method to improve safety and optimization accuracy compared to the existing technology. Summary of the Invention

[0005] The present invention solves the technical problems existing in the prior art and provides a wire-controlled four-wheel steering system and an optimization control method.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A wire-controlled four-wheel steering system includes a steering wheel assembly, a front wheel assembly, a rear wheel assembly and a main controller, the steering wheel assembly includes a steering wheel, a rotating rod and a return motor, the rotating rod is connected to the center position below the steering wheel, the lower end of the rotating rod is connected to the return motor, and a speed sensor is provided on the steering wheel; the front wheel assembly includes two front wheels, and the rear wheel assembly includes two rear wheels; the front wheels and the rear wheels are both driven by a steering motor, and the front wheels and the rear wheels are both provided with speed sensors; the speed sensor provided on the steering wheel, the speed sensors provided on the front wheels and the rear wheels, the steering motor, and the return motor are all electrically connected to the main controller.

[0007] Furthermore, a plurality of pressure sensors are provided on the outer sides of the front wheels and the outer sides of the rear wheels, and the pressure sensors are electrically connected to the main controller.

[0008] Furthermore, a camera is provided at the bottom of the vehicle, and the camera is used to take photos containing the complete outlines of the two front wheels and the complete outlines of the two rear wheels. The camera is electrically connected to the main controller.

[0009] An optimization control method for a wire-controlled four-wheel steering system comprises the following steps: S1. Obtaining the speed and angle of the steering wheel according to a speed sensor provided on the steering wheel, and obtaining the torque of the steering wheel according to a torque sensor provided on the steering wheel; S2. deriving a theoretical front wheel angle based on the steering wheel angle, and controlling the front wheel steering motor to rotate the front wheel to an angle corresponding to the theoretical angle; S3. deriving a theoretical steering angle of the rear wheels based on the vehicle speed, the steering wheel torque, and the theoretical steering angle of the front wheels, and controlling the steering motor of the rear wheels to rotate the rear wheels to an angle corresponding to the theoretical steering angle; S4. In the process of the front wheels and the rear wheels rotating to the theoretical turning angle, multiple time points are set, and at each time point, a first actual turning angle of the front wheel, a second actual turning angle of the front wheel, a first actual turning angle of the rear wheel, and a second actual turning angle of the rear wheel are obtained; a front wheel turning angle correction value is obtained based on the first actual turning angle of the front wheel and the second actual turning angle of the front wheel, and a rear wheel turning angle correction value is obtained based on the first actual turning angle of the rear wheel and the second actual turning angle of the rear wheel, and in the next time period after the time point, the actual turning angle of the front wheel and the actual turning angle of the rear wheel are corrected; the actual turning angle of the front wheel in the next time period is the theoretical turning angle of the next time period plus the front wheel turning angle correction value, and the actual turning angle of the rear wheel in the next time period is the theoretical turning angle of the next time period plus the rear wheel turning angle correction value.

[0010] Furthermore, the front wheel angle correction value and the rear wheel angle correction value are specifically calculated by the following formula: ; ; In the above formula, Indicates the front wheel angle correction value, represents the first weight value of the front wheel, represents the theoretical turning angle of the front wheel, Indicates the first actual turning angle of the front wheel, represents the second weight value of the front wheel, Indicates the second actual turning angle of the front wheel; Indicates the rear wheel angle correction value, represents the first weight value of the rear wheel, represents the theoretical turning angle of the rear wheel, Indicates the first actual turning angle of the rear wheel, represents the second weight value of the rear wheel, Indicates the second actual turning angle of the rear wheel.

[0011] Furthermore, at the first time point, when calculating the front wheel angle correction value and the rear wheel angle correction value, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are all 0.5; When calculating the front wheel angle correction value and the rear wheel angle correction value at the second time point and thereafter, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are dynamically adjusted.

[0012] Furthermore, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are dynamically adjusted specifically by the following formula: ; ; ; ; In the above formula, represents the first weight value of the front wheel after correction at the next time point, represents the second weight value of the front wheel after correction at the next time point, represents the first weight value of the rear wheel after correction at the next time point. Indicates the second weight value of the rear wheel after correction corresponding to the next time point.

[0013] Furthermore, the first actual turning angle of the front wheel and the first actual turning angle of the rear wheel are obtained by: obtaining the first actual turning angle of the front wheel and the first actual turning angle of the rear wheel according to the speed sensors provided on the front wheel and the rear wheel; The method for obtaining the second actual turning angle of the front wheels and the second actual turning angle of the rear wheels is as follows: rotate the front camera to take a picture to obtain a first picture, and after the front and rear wheels are rotated, the camera takes a picture again to obtain a second picture; obtain the initial positions of the two front wheels and the initial positions of the two rear wheels based on the first picture, and obtain the rotation positions of the two front wheels and the rotation positions of the two rear wheels based on the second picture; obtain the angles between the rotation positions of the two front wheels and the initial positions respectively, and take the average of the angles of the two front wheels as the second actual turning angle of the front wheels; obtain the angles between the rotation positions of the two rear wheels and the initial positions respectively, and take the average of the angles of the two rear wheels as the second actual turning angle of the rear wheels.

[0014] Furthermore, during the rotation of the front and rear wheels, the front wheel pressure values ​​and the rear wheel pressure values ​​are obtained according to the pressure sensors provided on the front and rear wheels, and the speed and direction of the return motor are adjusted according to the front wheel pressure values ​​and the rear wheel pressure values; when 、 When both are 0, the return motor does not work; when 、 When one or both of them are not 0, the speed and direction of the motor are adjusted according to the front wheel pressure value and the rear wheel pressure value; specifically: (1) When When the front wheel is in the forward direction, the motor speed and direction are adjusted according to the pressure on the front wheel. Specifically: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the first speed; 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the first speed; (2) When When the rear wheel pressure is taken into consideration, the motor speed and direction are adjusted as follows: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the second speed; 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the second speed; (3) When When the pressure on the rear wheel or the front wheel is taken into consideration, the speed and direction of the motor are adjusted. For details, refer to the method in (1) or (2); In the above formula, Indicates the pressure difference of the front wheels, Indicates the pressure difference of the rear wheels, Express Take the absolute value, Express Take the absolute value.

[0015] Furthermore, the first speed and the second speed are specifically calculated by the following formula: ; ; In the above formula, Indicates the first speed, Indicates the total number of pressure sensors on both front wheels, Indicates the steering wheel speed, Indicates the second speed, Indicates the total number of all non-zero pressure sensors on the rear wheels.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention first obtains the theoretical turning angles of the front wheels and the rear wheels based on the turning angle of the steering wheel, and then sets multiple time points during the rotation of the front wheels and the rear wheels. At each time point, the front wheel angle correction value and the rear wheel angle correction value are calculated for the rotation of the front wheels and the rear wheels in the previous time period, so that the turning angles of the front wheels and the rear wheels in each subsequent time period are more and more precise and accurate; at the same time, the present invention also sets multiple pressure sensors on the outside of the front wheels and the rear wheels to perform multi-point pressure value detection, and controls the steering and speed of the return motor according to the pressure conditions of the front wheels and the rear wheels to ensure the safety of the vehicle during driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of the system of the present invention.

[0018] Figure 2 It is a flow chart of the method of the present invention.

[0019] Description of reference numerals: 1. Steering wheel; 2. Turning rod; 3. Torque sensor; 4. Return motor; 5. Front connecting shaft; 6. Front wheel; 7. Rear connecting shaft; 8. Rear wheel; 9. Main controller. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0021] like Figure 1 As shown, the present invention provides a wire-controlled four-wheel steering system, including a steering wheel assembly, a front wheel assembly, a rear wheel assembly and a main controller. The steering wheel assembly includes a steering wheel, a rotating rod and a return motor. The rotating rod is fixedly connected to the center position below the steering wheel, the lower end of the rotating rod is connected to the return motor, the output end of the return motor is fixedly connected to the lower end of the rotating rod, and a torque sensor and a speed sensor are arranged on the steering wheel; the front wheel assembly includes two front wheels and a front connecting shaft, the two front wheels are connected by the front connecting shaft, and the front wheels are rotationally connected to the front connecting shaft; the rear wheel assembly includes two rear wheels and a rear connecting shaft, the two rear wheels are connected by the rear connecting shaft, and the rear wheels are rotationally connected to the rear connecting shaft; the front wheels and the rear wheels are both driven by the steering motor, and the front wheels and the rear wheels are both provided with speed sensors.

[0022] Multiple pressure sensors are installed on the outer wall of each front wheel and the outer wall of each rear wheel. A camera is installed at the bottom of the vehicle. The camera is used to take photos of the two front wheels and the two rear wheels. The photos taken need to include the entire front wheel and the entire rear wheel, that is, the outline of the front wheel and the outline of the rear wheel need to be shown in the photos.

[0023] The camera, all pressure sensors, the torque sensor and speed sensor arranged on the steering wheel, the speed sensors arranged on the front and rear wheels, the steering motor, and the return motor are all electrically connected to the main controller.

[0024] like Figure 2 As shown, the present invention also provides an optimization control method for a wire-controlled four-wheel steering system, comprising the following steps: S1. Obtain the rotation speed and angle of the steering wheel according to the rotation speed sensor provided on the steering wheel, and obtain the torque of the steering wheel according to the torque sensor provided on the steering wheel.

[0025] S2. According to the steering wheel angle, the theoretical steering angle of the front wheels is obtained. The theoretical steering angle of the front wheels is the steering wheel angle obtained in step S1. The steering is the same as the steering angle of the steering wheel. The main controller controls the steering motor of the front wheels to rotate according to the theoretical steering angle of the front wheels and the torque of the steering wheel, so that the front wheels rotate at an angle corresponding to the theoretical steering angle.

[0026] S3. According to the vehicle speed, the torque of the steering wheel and the theoretical steering angle of the front wheels, the theoretical steering angle and the direction of the rear wheels are obtained. The main controller controls the steering motor of the rear wheels to rotate so that the rear wheels rotate at an angle corresponding to the theoretical steering angle. According to the vehicle speed, the torque of the steering wheel and the theoretical steering angle of the front wheels, the theoretical steering angle and the direction of the rear wheels are obtained using existing methods, and the specific methods will not be repeated here.

[0027] S4. During the process of the front and rear wheels rotating to the theoretical turning angles, multiple time points are set. At each time point, a first actual turning angle of the front wheel, a second actual turning angle of the front wheel, a first actual turning angle of the rear wheel, and a second actual turning angle of the rear wheel are obtained. A front wheel turning angle correction value is obtained based on the first actual turning angle of the front wheel and the second actual turning angle of the front wheel, and a rear wheel turning angle correction value is obtained based on the first actual turning angle of the rear wheel and the second actual turning angle of the rear wheel. In the time period between the time point and the next time point, the actual turning angles of the front wheel and the rear wheel are corrected. The actual turning angle of the front wheel in the next time period is the theoretical turning angle of the next time period plus the front wheel turning angle correction value, and the actual turning angle of the rear wheel in the next time period is the theoretical turning angle of the next time period plus the rear wheel turning angle correction value.

[0028] The theoretical turning angle of the front wheel in each time period is the theoretical turning angle of the front wheel obtained in step S2. times, the theoretical rotation angle of the rear wheel in each time period is the theoretical rotation angle of the rear wheel obtained in step S3 times.

[0029] The first actual turning angle of the front wheel and the first actual turning angle of the rear wheel are obtained by: obtaining the first actual turning angle of the front wheel and the first actual turning angle of the rear wheel according to the speed sensors provided on the front wheel and the rear wheel.

[0030] The method for obtaining the second actual turning angle of the front wheels and the second actual turning angle of the rear wheels is as follows: rotate the front camera to take a photo to obtain a first photo, and after the front and rear wheels are rotated, the camera takes a photo again to obtain a second photo; obtain the initial positions of the two front wheels and the initial positions of the two rear wheels based on the first photo, and obtain the rotation positions of the two front wheels and the rotation positions of the two rear wheels based on the second photo; obtain the angles between the rotation positions of the two front wheels and the initial positions, and take the average of the angles of the two front wheels as the second actual turning angle of the front wheels; obtain the angles between the rotation positions of the two rear wheels and the initial positions, and take the average of the angles of the two rear wheels as the second actual turning angle of the rear wheels.

[0031] The front wheel angle correction value is obtained based on the first actual front wheel angle and the second actual front wheel angle; the rear wheel angle correction value is obtained based on the first actual rear wheel angle and the second actual rear wheel angle. The front wheel angle correction value and the rear wheel angle correction value are specifically calculated using the following formula: ; ; In the above formula, Indicates the front wheel angle correction value, represents the first weight value of the front wheel, represents the theoretical turning angle of the front wheel, Indicates the first actual turning angle of the front wheel, represents the second weight value of the front wheel, Indicates the second actual turning angle of the front wheel; Indicates the rear wheel angle correction value, represents the first weight value of the rear wheel, represents the theoretical turning angle of the rear wheel, Indicates the first actual turning angle of the rear wheel, represents the second weight value of the rear wheel, Indicates the second actual turning angle of the rear wheel.

[0032] At the first time point, when calculating the front wheel angle correction value and the rear wheel angle correction value, 、 、 、 All are set to 0.5. At the second time point and the time points thereafter, when the front wheel angle correction value and the rear wheel angle correction value are used, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are dynamically adjusted. Specifically, the dynamic adjustment is performed using the following formula: ; ; ; ; In the above formula, represents the first weight value of the front wheel after correction at the next time point, represents the second weight value of the front wheel after correction at the next time point, represents the first weight value of the rear wheel after correction at the next time point. Indicates the second weight value of the rear wheel after correction corresponding to the next time point.

[0033] The pressure value detected by the pressure sensor set on the front wheel is recorded as the front wheel pressure value, and the pressure value detected by the pressure sensor set on the rear wheel is recorded as the rear wheel pressure value. The speed and direction of the motor are adjusted according to the front wheel pressure value and the rear wheel pressure value. The specific adjustment method is as follows: Get the pressure value detected by the pressure sensor set on the left front wheel, recorded as , all Add up and get the total pressure of the left front wheel, recorded as ; Get the pressure value detected by the pressure sensor set on the right front wheel, recorded as , all Add up and get the total pressure of the right front wheel, recorded as ; Subtract the total pressure value of the left front wheel from the total pressure value of the right front wheel to obtain the pressure difference of the front wheels, which is recorded as .

[0034] Get the pressure value detected by the pressure sensor set on the left rear wheel, and record it as , all Add up and get the total pressure of the left rear wheel, recorded as ; Get the pressure value detected by the pressure sensor set on the right rear wheel, recorded as , all Add up and get the total pressure of the right rear wheel, recorded as ; Subtract the total pressure value of the left rear wheel from the total pressure value of the right rear wheel to obtain the pressure difference of the rear wheels, which is recorded as .

[0035] when 、 When both are 0, the return motor does not work.

[0036] when 、 When one or both of them are not 0, the motor speed and direction are adjusted according to the front wheel pressure value and the rear wheel pressure value. (1) When When the front wheel is in the forward direction, the motor speed and direction are adjusted according to the pressure on the front wheel. Specifically: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the first speed.

[0037] 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the first speed.

[0038] (2) When When the rear wheel pressure is taken into consideration, the motor speed and direction are adjusted as follows: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the second speed.

[0039] 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the second speed.

[0040] (3) When When adjusting the speed and direction of the motor, consider the pressure of the rear wheel or the pressure of the front wheel. For details, refer to the method in (1) or (2).

[0041] In the above formula, Express Take the absolute value, Express Take the absolute value.

[0042] The first speed and the second speed are calculated by the following formula: ; ; In the above formula, Indicates the first speed, Indicates the total number of pressure sensors on both front wheels, Indicates the steering wheel speed, Indicates the second speed, Indicates the total number of all non-zero pressure sensors on the rear wheels.

[0043] The present invention first obtains the theoretical turning angles of the front wheels and the rear wheels based on the turning angle of the steering wheel, and then sets multiple time points during the rotation of the front wheels and the rear wheels. At each time point, the front wheel angle correction value and the rear wheel angle correction value are calculated for the rotation of the front wheels and the rear wheels in the previous time period, so that the turning angles of the front wheels and the rear wheels in each subsequent time period are more and more precise and accurate; at the same time, the present invention also sets multiple pressure sensors on the outside of the front wheels and the rear wheels to perform multi-point pressure value detection, and controls the steering and speed of the return motor according to the pressure conditions of the front wheels and the rear wheels to ensure the safety of the vehicle during driving.

[0044] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A wire-controlled four-wheel steering system, characterized in that: It includes a steering wheel assembly, a front wheel assembly, a rear wheel assembly and a main controller. The steering wheel assembly includes a steering wheel, a rotating rod and a return motor. The rotating rod is connected to the center position below the steering wheel, and the lower end of the rotating rod is connected to the return motor. A speed sensor is provided on the steering wheel; the front wheel assembly includes two front wheels, and the rear wheel assembly includes two rear wheels; the front wheels and the rear wheels are both driven by a steering motor, and speed sensors are provided on the front wheels and the rear wheels; the speed sensor provided on the steering wheel, the speed sensors provided on the front wheels and the rear wheels, the steering motor, and the return motor are all electrically connected to the main controller.

2. The four-wheel steering by wire system according to claim 1, characterized in that: A plurality of pressure sensors are provided on the outer sides of the front wheels and the outer sides of the rear wheels, and the pressure sensors are electrically connected to the main controller.

3. The four-wheel steering by wire system according to claim 1, characterized in that: A camera is provided at the bottom of the vehicle, and is used for taking photos containing the complete outlines of the two front wheels and the complete outlines of the two rear wheels. The camera is electrically connected to the main controller.

4. The optimization control method of a wire-controlled four-wheel steering system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Obtaining the speed and angle of the steering wheel according to a speed sensor provided on the steering wheel, and obtaining the torque of the steering wheel according to a torque sensor provided on the steering wheel; S2. deriving a theoretical front wheel angle based on the steering wheel angle, and controlling the front wheel steering motor to rotate the front wheel to an angle corresponding to the theoretical angle; S3. deriving a theoretical steering angle of the rear wheels based on the vehicle speed, the steering wheel torque, and the theoretical steering angle of the front wheels, and controlling the steering motor of the rear wheels to rotate the rear wheels to an angle corresponding to the theoretical steering angle; S4. In the process of the front wheels and the rear wheels rotating to the theoretical turning angle, multiple time points are set, and at each time point, a first actual turning angle of the front wheel, a second actual turning angle of the front wheel, a first actual turning angle of the rear wheel, and a second actual turning angle of the rear wheel are obtained; a front wheel turning angle correction value is obtained based on the first actual turning angle of the front wheel and the second actual turning angle of the front wheel, and a rear wheel turning angle correction value is obtained based on the first actual turning angle of the rear wheel and the second actual turning angle of the rear wheel, and in the next time period after the time point, the actual turning angle of the front wheel and the actual turning angle of the rear wheel are corrected; the actual turning angle of the front wheel in the next time period is the theoretical turning angle of the next time period plus the front wheel turning angle correction value, and the actual turning angle of the rear wheel in the next time period is the theoretical turning angle of the next time period plus the rear wheel turning angle correction value.

5. The optimization control method of a wire-controlled four-wheel steering system according to claim 4, characterized in that: The front wheel angle correction value and the rear wheel angle correction value are calculated using the following formula: ； ； In the above formula, Indicates the front wheel angle correction value, represents the first weight value of the front wheel, represents the theoretical turning angle of the front wheel, Indicates the first actual turning angle of the front wheel, represents the second weight value of the front wheel, Indicates the second actual turning angle of the front wheel; Indicates the rear wheel angle correction value, represents the first weight value of the rear wheel, represents the theoretical turning angle of the rear wheel, Indicates the first actual turning angle of the rear wheel, represents the second weight value of the rear wheel, Indicates the second actual turning angle of the rear wheel.

6. The optimization control method of a wire-controlled four-wheel steering system according to claim 5, characterized in that: At the first time point, when calculating the front wheel angle correction value and the rear wheel angle correction value, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are all 0.5; When calculating the front wheel angle correction value and the rear wheel angle correction value at the second time point and thereafter, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are dynamically adjusted.

7. The optimization control method of a wire-controlled four-wheel steering system according to claim 6, characterized in that: Specifically, the first weight value of the front wheel, the second weight value of the front wheel, the first weight value of the rear wheel, and the second weight value of the rear wheel are dynamically adjusted by the following formula: ； ； ； ； In the above formula, represents the first weight value of the front wheel after correction at the next time point, represents the second weight value of the front wheel after correction at the next time point, represents the first weight value of the rear wheel after correction at the next time point. Indicates the second weight value of the rear wheel after correction corresponding to the next time point.

8. The optimization control method of a wire-controlled four-wheel steering system according to claim 4, characterized in that: The first actual turning angle of the front wheel and the first actual turning angle of the rear wheel are obtained by: obtaining the first actual turning angle of the front wheel and the first actual turning angle of the rear wheel according to the speed sensors provided on the front wheel and the rear wheel; The second actual turning angle of the front wheels and the second actual turning angle of the rear wheels are obtained by rotating the front camera to take a picture to obtain a first picture, and after the front and rear wheels rotate, the camera takes a picture again to obtain a second picture; the initial positions of the two front wheels and the initial positions of the two rear wheels are obtained based on the first picture, and the rotational positions of the two front wheels and the rotational positions of the two rear wheels are obtained based on the second picture; The angles between the two front wheel rotation positions and the initial positions are obtained respectively, and the average of the two front wheel angles is taken as the second actual turning angle of the front wheels; the angles between the two rear wheel rotation positions and the initial positions are obtained respectively, and the average of the two rear wheel angles is taken as the second actual turning angle of the rear wheels.

9. The optimization control method of a wire-controlled four-wheel steering system according to claim 4, characterized in that: During the rotation of the front and rear wheels, the pressure sensors provided on the front and rear wheels obtain the front and rear wheel pressure values, and adjust the motor speed and steering according to the front and rear wheel pressure values; when 、 When both are 0, the return motor does not work; when 、 When one or both of them are not 0, the speed and direction of the motor are adjusted according to the front wheel pressure value and the rear wheel pressure value; specifically: (1) When When the front wheel is in the forward direction, the motor speed and direction are adjusted according to the pressure on the front wheel. Specifically: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the first speed; 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the first speed; (2) When When the rear wheel pressure is taken into consideration, the motor speed and direction are adjusted as follows: 1) When When the motor rotates in the direction of controlling the steering wheel to turn right, the speed of the motor is the second speed; 2) When When the motor rotates in the direction of controlling the steering wheel to turn left, the speed of the motor is the second speed; (3) When When the pressure on the rear wheel or the front wheel is taken into consideration, the speed and direction of the motor are adjusted. For details, refer to the method in (1) or (2); In the above formula, Indicates the pressure difference of the front wheels, Indicates the pressure difference of the rear wheels, Express Take the absolute value, Express Take the absolute value.

10. The optimization control method of a wire-controlled four-wheel steering system according to claim 9, characterized in that: The first speed and the second speed are calculated by the following formula: ； ； In the above formula, Indicates the first speed, Indicates the total number of pressure sensors on both front wheels, Indicates the steering wheel speed, Indicates the second speed, Indicates the total number of all non-zero pressure sensors on the rear wheels.

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