Four-wheeler steering control system with minimum turning radius characteristic

Abstract

The invention discloses a four-wheeler steering control system with the minimum turning radius characteristic, and relates to the field of four-wheeler control systems. According to the four-wheeler steering control system with the minimum turning radius characteristic, the traveling speeds of front and rear wheels of a vehicle body and the respective steering angles of the two front wheels are calculated based on inherent parameters of the four-wheeler and combined parameters of motion control quantities, and a steering center external model and a steering center built-in model are designed according to the traveling speeds; therefore, on the premise that internal torque is not generated, the minimum movement radius allowed by the wheel structure of the four-wheeler is achieved, calculation methods of all control quantities of the steering control system and calculation formulas of the minimum movement radius which can be achieved in different control modes are clearly given, and the calculation method of the wheel structure of the four-wheeler is used for controlling the wheel structure of the four-wheeler. Therefore, the vehicle is effectively controlled to reach the minimum movement radius, the field adaptability of the four-wheeler is improved, the cumbersome differential mechanism and steering linkage design of a traditional vehicle is abandoned, and the production and manufacturing difficulty and the maintenance cost of the vehicle are effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of four-wheeled vehicle control systems, and specifically to a four-wheeled vehicle steering control system with the characteristic of minimum turning radius. Background Art

[0002] Disadvantages of traditional automobile steering control systems: 1. The steering system of traditional automobiles is very complex, including relatively heavy steering control structures and functional components such as differentials. However, in industrial and agricultural sites, there are often relatively strict requirements for the vehicle body weight and cost. Therefore, such a steering control system is difficult to meet the requirements for vehicle body weight and cost in industrial or agricultural sites. 2. Affected by the steering structure, the minimum turning radius that can be achieved by traditional automobiles is still relatively large, making it difficult to meet the requirements for the turning radius of vehicles in industrial and agricultural sites.

[0003] Disadvantages of tracked vehicle steering control systems: 1. The moving structural components of tracked vehicles are relatively complex, including complex transmission and support structures, and the production and maintenance costs are relatively high; 2. The tracked structure of light vehicles is difficult to achieve flexible steering actions on rough roads, so it is difficult to apply on small transportation platforms in industrial or agricultural sites; 3. The steering control of tracked vehicles relies on the differential of the left and right tracks. If the same control method is directly adopted on four-wheeled vehicles, it will cause excessive torque resistance between the front and rear wheel groups, resulting in the inability to achieve steering actions. 4. The actual effect of differential steering control of tracked vehicles is greatly affected by the ground flatness, and it is difficult to accurately estimate the actual steering angle and the time consumed during the steering process, which increases the design difficulty of the upper control logic.

[0004] Disadvantages of four-wheel steering control systems: 1. The four-wheel steering control system requires that all four wheels have steering capabilities, and the production and maintenance costs are relatively high; 2. When the load capacity of four-wheeled vehicles is strong, generally larger-sized wheels are used, and the matching steering structure will also be very heavy, thus increasing the overall weight of the whole machine; 3. The rear wheels of common four-wheeled vehicles in current industrial and agricultural sites generally do not have steering functions, so the applicability of four-wheel steering control systems is limited.

[0005] In view of the above technical disadvantages, the present invention designs a four-wheeled vehicle steering control system based on front-wheel steering. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a four-wheeled vehicle steering control system with the characteristic of minimum turning radius, which is used to solve the problem of realizing a four-wheeled vehicle motion control system without internal torque resistance by relying on an independent front-wheel steering function under the condition of limited motion space in industrial and agricultural sites, and the turning radius of this steering control system can reach the minimum turning radius allowed by the structure.

[0007] To achieve the above object, the present invention is realized through the following technical solutions: A four-wheel vehicle steering control system with the characteristic of minimum turning radius, including a data acquisition module, a data processing module, a vehicle steering model, a data output module, and an execution module. The data acquisition module is used to acquire the steering speed and angle of the four wheels when the four-wheel vehicle steers. Then, the data processing module processes and analyzes the steering speed and angle data, calculates the minimum turning radius through the vehicle steering model, and then outputs the data to the execution module through the data output module. The execution module controls the front-wheel steering; Among them, the vehicle steering model is characterized by the position where the steering center of the four-wheel vehicle is located, including an external steering center model and an internal steering center model; Let be the longitudinal length of the vehicle body, be half of the left-right width of the vehicle body, be the distance from the steering center to the outer edge of the vehicle body, be the turning radius of the left front wheel, be the turning radius of the right front wheel; the angle be the steering angle of the left front wheel, be the steering angle of the right front wheel; be the control quantity of the traveling speed of the vehicle body, be the traveling speed of the left rear wheel, be the traveling speed of the right rear wheel, be the projection of the left front wheel speed on the rear axle line, be the projection of the right front wheel speed on the rear axle line; In the external steering center model:

[0008] When, the minimum movement radius in the state where the steering center is located outside the vehicle body is reached, and the minimum movement radius is: ; In the internal steering center model;

[0009] At that time, when the steering center of the vehicle body moves inwards to coincide with the longitudinal center line of the vehicle body, the minimum turning radius is: .

[0010] Preferably, the data acquisition module includes speed sensors installed on the four wheels of the four-wheel vehicle for speed monitoring; and steering angle sensors installed on the left and right front wheels on the front side of the four-wheel vehicle.

[0011] Preferably, the data acquisition module includes speed sensors installed on the four wheels of the four-wheel vehicle for speed monitoring; and steering angle sensors installed on the left and right front wheels on the front side of the four-wheel vehicle.

[0012] Preferably, the data processing module and the vehicle steering model are both written into the four-wheel vehicle steering controller, and data is acquired in real time through the controller from the speed sensors and the steering angle sensors.

[0013] Preferably, the execution module includes wheel drivers installed on the four wheels of the four-wheel vehicle. The wheel drivers are controlled and connected to the four-wheel vehicle steering controller. By transmitting the collected wheel speed and steering angle information to the controller in a wired or wireless manner, the controller fuses the control data sent by the upper-layer intelligent control logic, processes the data using the vehicle steering model, obtains the steering control quantities of the left and right front wheels and the speed control quantities of each wheel. The controller transmits the results of these data processes to the wheel drivers through wired or wireless communication, and the wheel drivers are responsible for completing the speed closed-loop and steering angle closed-loop control logics.

[0014] Preferably, in the vehicle steering model, and are the inherent properties of the vehicle body, and are the control quantities sent by the upper-layer control logic. The main function of this steering control system is to calculate reasonable , , , , and and other control quantities according to these known quantities.

[0015] Preferably, in the built-in model of the steering center, since the steering center enters the vehicle body, compared with when the steering center is located outside the vehicle body, the turning radius at this time is smaller. At this time represents the distance of the steering center relative to the longitudinal center of the vehicle body.

[0016] Preferably, during the steering process, when the steering center enters the vehicle body, if the same control method as when the steering center is outside the vehicle body is continued, the rotation angle of the left front wheel will be greater than 90 degrees. If the front-wheel steering structure supports this control method, the "external steering center model" is continued for control; if the front-wheel steering structure does not support a steering control of more than 90 degrees, the "internal steering center model" is used for control.

[0017] Preferably, in the "internal steering center model", the steering center is located inside the vehicle body. At this time , so the steering angle of the left front wheel is a negative angle. At the same time and are both negative; and because the rotation direction of the left front wheel is opposite to the speed direction, the speed of the left front wheel is also negative. Therefore, in the "internal steering center model", the steering angles and traveling speeds of the left and right front wheels both satisfy the relationship of being the same in magnitude and opposite in direction.

[0018] Preferably, in the "internal steering center model", when the steering center is on the right side of the longitudinal center of the vehicle body, its minimum turning radius is the same as that when the steering center is on the left side of the longitudinal center of the vehicle body.

[0019] Preferably, when the front-wheel spacing and the rear-wheel spacing of the vehicle are not equal or the front and rear wheel sizes are different, the width of the vehicle body is based on the width of the front wheels during the data processing, and the speed control amount of the rear wheels is scaled proportionally.

[0020] The present invention discloses a four-wheel vehicle steering control system with the characteristic of minimum turning radius, and its beneficial effects are as follows: 1. The four-wheel vehicle steering control system with the characteristic of minimum turning radius calculates the traveling speeds of the front and rear wheels of the vehicle body, as well as the steering angles of the two front wheels respectively, based on the inherent parameters of the four-wheel vehicle and the combined parameters of the motion control amount. Thus, without generating internal torque, the minimum motion radius allowed by the structure is achieved, and the calculation methods of each control amount of the steering control system are clearly given, as well as the calculation formula of the minimum turning radius that can be achieved under different control modes. Thereby, the vehicle is effectively controlled to reach the minimum motion radius, improving the site adaptability of the four-wheel vehicle.

[0021] 2. The four-wheel steering control system with the minimum turning radius characteristic controls the front wheels of the four-wheel vehicle to turn independently and controls the speeds of the four wheels of the four-wheel vehicle respectively. Thus, it abandons the bulky differential and steering linkage design of traditional automobiles, and the rear wheels do not need to have the steering ability. Only two front wheels with relatively independent and simple steering structures can achieve flexible steering control, which is more suitable for the light four-wheel vehicles commonly seen in industrial and agricultural sites, and reduces the difficulty of the four-wheel vehicle structure design, avoiding the use of complex transmission and steering structures, thereby effectively reducing the production and maintenance costs of the vehicle.

[0022] 3. The four-wheel steering control system with the minimum turning radius characteristic comprehensively designs the front-wheel steering angle and the speed control amounts of each wheel, and thus maximally avoids the generation of internal torque, ensuring the overall reliability of the four-wheel vehicle, effectively avoiding unnecessary energy consumption at the same time, and improving the working duration of the vehicle. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0024] Figure 1 It is the functional architecture diagram of the four-wheel vehicle steering control system of the present invention; Figure 2 It is the overall electrical block diagram of the four-wheel vehicle steering control system of the present invention; Figure 3 It is the schematic diagram of the steering center located outside the vehicle body of the present invention; Figure 4 It is the schematic diagram of the steering center located inside the vehicle body of the present invention; Figure 5 It is the schematic diagram of the minimum movement radius of the present invention. Detailed Embodiments

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0026] Embodiments of the present application provide a four-wheel vehicle steering control system with the characteristic of minimum turning radius, which is used to solve the problem that in the case of limited movement space in industrial and agricultural sites, relying on the independent front-wheel steering function to achieve a four-wheel vehicle motion control system without internal torque resistance, and the turning radius of this steering control system can reach the minimum turning radius allowed by the structure.

[0027] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the specification drawings and specific implementation manners.

[0028] Embodiments of the present invention disclose a four-wheel vehicle steering control system with the characteristic of minimum turning radius.

[0029] According to the attached Figures 1-5 As shown, this steering control system requires the front wheels of the four-wheel vehicle to have the steering ability at a certain angle, and the steering structures of the left and right front wheels are relatively independent. This steering control system converts control quantities such as the traveling speed and turning radius issued by the upper-layer application into the traveling speed control quantities and front-wheel steering angle control quantities of each wheel, and then based on speed closed-loop control and angle closed-loop control, realizes motion control functions such as the traveling and steering of the vehicle. The "traveling speed" mentioned here refers to the motion speed of the vehicle body center axis in the forward direction, and the "turning radius" refers to the distance between the longitudinal center axis of the vehicle body and the steering center.

[0030] In this steering control system, the left and right front wheels adopt independent steering control structures. Therefore, the left and right front wheels do not need to be connected by a connecting rod or a rotating shaft, but the controller coordinates the steering angles of the left and right front wheels to complete the steering function.

[0031] At the same time, the entire steering control system includes a data acquisition module, a data processing module, a vehicle steering model, a data output module, and an execution module. The data acquisition module is used to acquire the steering speeds and angles of the four wheels when the four-wheel vehicle steers. Then, the data processing module processes and analyzes the steering speed and angle data, calculates the minimum turning radius through the vehicle steering model, and then outputs the data through the data output module to the execution module. The execution module controls the front-wheel steering. The vehicle steering model is distinguished by the position where the steering center of the four-wheel vehicle is located, and includes an external steering center model and an internal steering center model; The data acquisition module includes speed sensors installed on the four wheels of the four-wheeled vehicle for speed monitoring; and steering angle sensors installed on the left and right wheels on the front side of the four-wheeled vehicle. The data processing module and the vehicle steering model are both written into the steering controller of the four-wheeled vehicle. Data is acquired in real time through the controller from the speed sensors and the steering angle sensors. The execution module includes wheel drivers installed on the four wheels of the four-wheeled vehicle. The wheel drivers are control-connected to the steering controller of the four-wheeled vehicle. By transmitting the acquired wheel speed and steering angle information to the controller in a wired or wireless manner, the controller fuses the control data sent by the upper-layer intelligent control logic, processes the data using the vehicle steering model, obtains the steering control quantities of the left and right front wheels and the speed control quantities of each wheel. The controller transmits the results of these data processes to the wheel drivers through wired or wireless communication, and the wheel drivers are responsible for completing the speed closed-loop and steering angle closed-loop control logics To avoid internal torque generated by the vehicle's own structure, the four wheels of the four-wheeled vehicle need to make circular motions around the same steering center. When the steering center is located outside the vehicle body, the relationship between the traveling speed and the steering angle of the wheels is as Figure 2 shown; Among them, is the longitudinal length of the vehicle body, is half of the left-right width of the vehicle body, is the distance from the steering center to the outer edge of the vehicle body, is the turning radius of the left front wheel, is the turning radius of the right front wheel; the angle is the steering angle of the left front wheel, is the steering angle of the right front wheel; is the traveling speed control quantity of the vehicle body, is the traveling speed of the left rear wheel, is the traveling speed of the right rear wheel, is the projection of the left front wheel speed on the rear axle line, is the projection of the right front wheel speed on the rear axle line.

[0032] Among all the above control quantities, and are the inherent properties of the vehicle body, and are the control quantities sent by the upper-layer control logic. The main function of this steering control system is to calculate reasonable , , , , and and other control quantities according to these known quantities. In the state where the steering center is located outside the vehicle body, the relationship between each control quantity and the known quantity is as follows:

[0033] When reaches the minimum turning radius in the state where the steering center is located outside the vehicle body, the minimum turning radius is:

[0034] When the steering center enters the vehicle body, relative to the steering center being located outside the vehicle body, the turning radius at this time is smaller, as Figure 3 shown: Among them, is the distance of the steering center relative to the longitudinal center of the vehicle body.

[0035] At this time, if the same control method as when the steering center is located outside the vehicle body is continued to be used, the situation where the turning angle of the left front wheel is greater than 90 degrees will occur. If the front wheel steering structure supports this control method, this method can continue to be used for control. However, if the front wheel steering structure does not support such a large-angle steering control, in order to achieve a smaller turning radius, different control modes can be defined according to the relative position of the steering center and the vehicle body, and then different calculation methods can be adopted for different control modes. For example, the steering control mode can be divided into a "steering center external model" and a "steering center internal model", corresponding to Appendix Figure 2 and Appendix Figure 3 .

[0036] Under the "steering center internal model", the steering center is located inside the vehicle body. At this time, the steering angle of the left front wheel is no longer greater than 90 degrees, but becomes a negative angle. The calculation methods for the traveling speed of each wheel and the front wheel steering angle at this time are as follows:

[0037] Among them, because under the "steering center internal model", so and are both negative values; at the same time, because the rotation direction of the left front wheel is opposite to the speed direction, the speed of the left front wheel is also a negative value.

[0038] The steering center of the vehicle body continues to move inwards until it coincides with the longitudinal center line of the vehicle body. At this time, the turning radius reaches the minimum value, as Figure 4 shown: Under the "built-in steering center model", the steering angles and traveling speeds of the left and right front wheels at this time both satisfy the relationship of being equal in magnitude and opposite in direction. The minimum turning radius obtained at this time is:

[0039] When the steering center is on the right side of the longitudinal center of the vehicle body, the calculation method is the same as above.

[0040] If the steering angle range of the front wheels cannot reach the maximum angle range allowed in the above control system due to limitations of the front-wheel steering structure, this steering control algorithm is still applicable, but the actual minimum turning radius may be greater than the value of the minimum movement radius mentioned here.

[0041] If the wheelbase between the front wheels and the rear wheels of the vehicle is not equal, or the front and rear wheels have different sizes, this control system can also be used. During the data processing, the width of the vehicle body is based on the width of the front wheels, and the speed control amount of the rear wheels is scaled proportionally on the basis of this steering control system, and the steering movement control amount of this type of vehicle can be obtained.

[0042] Working principle; The present invention proposes a four-wheel vehicle steering control system with practical use value. This control system can calculate the traveling speeds of the front and rear wheels of the vehicle body and the steering angles of the two front wheels respectively based on the inherent parameters of the four-wheel vehicle and the combined parameters of the movement control amount, so as to achieve the minimum movement radius allowed by the structure without generating internal torque. And in the present invention, the calculation methods of each control amount of the steering control system and the calculation formula of the minimum movement radius that can be achieved under different control modes are clearly given.

[0043] At the same time, the present invention proposes a combination method of the vehicle body movement control amount different from the traditional control method. This control amount combination method includes the traveling speed of the vehicle body and the turning radius. This combination method is applicable to the movement control logic facing the turning radius and can effectively reduce the design difficulty of the upper-layer intelligent control logic.

[0044] According to the relative position relationship between the steering center and the vehicle body, the present invention proposes two ways of dividing the control modes. Among them, the "built-in steering center model" effectively reduces the requirement of the steering control system for the steering angle range of the front wheels. Under the same physical structure, a smaller turning radius can be achieved, improving the site adaptability of the four-wheel vehicle.

[0045] Compared with traditional automobiles, tracked vehicles, and four-wheel steering control methods, the present invention has the following advantages: 1. Product lightweight: Vehicles using this algorithm can abandon the heavy differential and steering linkage designs of traditional cars. The rear wheels do not need to have steering capabilities either. Only two front wheels with relatively independent and simple steering structures are required to achieve flexible steering control, making it more suitable for light four-wheel vehicles commonly seen in industrial and agricultural sites. 2. Relatively low product cost: The present invention reduces the difficulty of the structural design of four-wheel vehicles and avoids the use of complex transmission and steering structures, thus effectively reducing the production and maintenance costs of the vehicles. 3. High product reliability and low power consumption: The present invention comprehensively designs the steering angle of the front wheels and the speed control amounts of each wheel, thereby maximizing the avoidance of internal torque generation, ensuring the overall reliability of the four-wheel vehicle, effectively avoiding unnecessary energy consumption, and increasing the working duration of the vehicle. 4. Quantifiable control effect: Compared with the problem that it is difficult to estimate the actual steering angle and turning radius in the left-right differential control of tracked vehicles, the turning radius of this steering control system can be directly calculated, making the effect of steering control quantifiable, the trajectory of the vehicle predictable, and it is well adapted to the upper-layer intelligent control logic, reducing the design difficulty of the upper-layer control logic.

[0046] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A four-wheel vehicle steering control system with minimum turning radius characteristics, comprising a data acquisition module, a data processing module, a vehicle steering model, a data output module, and an execution module, characterized in that The data acquisition module is used to obtain the steering speeds and angles of the four wheels when the four-wheeled vehicle steers. Then, the data processing module processes and analyzes the steering speed and angle data, calculates the minimum turning radius through the vehicle steering model, and then outputs the data to the execution module through the data output module. The execution module controls the front-wheel steering. Among them, the vehicle steering model is distinguished by the position of the steering center of the four-wheeled vehicle, including an external steering center model and an internal steering center model. Let be the longitudinal length of the vehicle body, be half of the left - right width of the vehicle body, be the distance from the steering center to the outer edge of the vehicle body, be the turning radius of the left front wheel, be the turning radius of the right front wheel; the angle be the steering angle of the left front wheel, be the steering angle of the right front wheel; be the control quantity of the vehicle body's traveling speed, be the traveling speed of the left rear wheel, be the traveling speed of the right rear wheel, be the projection of the left front wheel speed on the rear axle line, be the projection of the right front wheel speed on the rear axle line; In the external steering center model: When the minimum turning radius in the state where the turning center is located outside the vehicle body is reached, and the minimum turning radius is: ； In the internal steering center model; When When the steering center of the vehicle body moves inwards to coincide with the longitudinal center line of the vehicle body, the minimum turning radius is: 。 2. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 1, characterized in that: The data acquisition module includes speed sensors installed on the four wheels of the four-wheeled vehicle for speed monitoring; and steering angle sensors installed on the left and right front wheels of the front side of the four-wheeled vehicle.

3. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 2, characterized in that: The data processing module and the vehicle steering model are both written into the four-wheeled vehicle steering controller, and data is obtained in real time through the controller from the speed sensors and the steering angle sensors.

4. A four-wheeled vehicle steering control system with a minimum turning radius characteristic according to claim 3, characterized in that: The execution module includes wheel drivers installed on the four wheels of the four-wheeled vehicle. The wheel drivers are controlled and connected to the four-wheeled vehicle steering controller. By transmitting the collected wheel speed and steering angle information to the controller in a wired or wireless manner, the controller integrates the control data sent by the upper-layer intelligent control logic, processes the data using the vehicle steering model, obtains the steering control amounts of the left and right front wheels and the speed control amounts of each wheel. The controller transmits the results of these data processes to the wheel drivers through wired or wireless communication, and the wheel drivers are responsible for completing the speed closed-loop and steering angle closed-loop control logics.

5. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 1, characterized in that: In the vehicle steering model, and are the inherent properties of the vehicle body, and are the control variables issued by the upper control logic. The main function of this steering control system is to calculate reasonable , , , , and and other control variables.

6. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 1, characterized in that: In the built-in model of the steering center, since the steering center enters the interior of the vehicle body, it is located outside the vehicle body relative to the steering center, and the turning radius at this time is smaller. At this time It is expressed as the distance between the steering center and the longitudinal center of the vehicle body.

7. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 6, characterized in that: During the steering process, when the steering center enters the vehicle body, if the same control method as when the steering center is outside the vehicle body is continued to be used at this time, the situation where the turning angle of the left front wheel is greater than 90 degrees will occur. If the front-wheel steering structure supports this control method, the "external steering center model" is continued to be used for control; if the front-wheel steering structure does not support a steering control greater than 90 degrees, the "internal steering center model" is used for control.

8. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 1, characterized in that: In the "built-in steering center model", the steering center is located inside the vehicle body. At this time , so the steering angle of the left front wheel is a negative angle. At the same time and are both negative; and because the rotation direction of the left front wheel is opposite to the speed direction, the speed of the left front wheel is also negative. Therefore, in the "built-in steering center model", the steering angles and traveling speeds of the left and right front wheels both satisfy the relationship of the same magnitude and opposite directions.

9. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 8, characterized in that: In the "internal steering center model", when the steering center is on the right side of the longitudinal center of the vehicle body, its minimum movement radius is the same as the case when the steering center is on the left side of the longitudinal center of the vehicle body.

10. A four-wheel vehicle steering control system with a minimum turning radius characteristic according to claim 1, characterized in that: When the front-wheel spacing and the rear-wheel spacing of the vehicle are not equal or the front and rear wheel sizes are different, the width of the vehicle body is based on the width of the front wheels during the data processing process, and the speed control amount of the rear wheels is scaled proportionally.

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