A steering control system for four-wheel vehicles with minimum turning radius characteristics

Abstract

The present invention discloses a steering control system for a four-wheeled vehicle with a minimum turning radius characteristic, relating to the field of four-wheeled vehicle control systems. The steering control system for a four-wheeled vehicle with a minimum turning radius characteristic calculates the travel speeds of the front and rear wheels of the vehicle body, as well as the steering angles of the two front wheels, based on the inherent parameters of the four-wheeled vehicle and the combined parameters of motion control quantities. Based on these calculations, an external steering center model and an internal steering center model are designed to achieve the minimum motion radius allowed by the four-wheeled vehicle wheel structure without generating internal torque. The system also clearly provides calculation methods for each control quantity of the steering control system, as well as calculation formulas for the minimum motion radius achievable under different control modes. This effectively controls the vehicle to achieve the minimum motion radius, improves the site adaptability of the four-wheeled vehicle, eliminates the bulky differential and steering linkage design of traditional automobiles, and effectively reduces the vehicle's manufacturing difficulty and maintenance costs.

Description

Technical Field

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

[0002] Disadvantages of traditional automotive steering control systems: 1. Traditional automotive steering systems are highly complex, including bulky steering control structures and functional components such as differentials. Industrial and agricultural applications often place stringent weight and cost requirements on vehicle bodies, making it difficult for these steering control systems to meet these requirements. 2. Due to the influence of the steering structure, the minimum achievable turning radius of traditional automotive steering systems remains relatively large, making it difficult to meet the required turning radius requirements in industrial and agricultural applications.

[0003] Disadvantages of the tracked vehicle steering control system: 1. The motion structure components of the tracked vehicle are relatively complex, including complex transmission and support structures, and the production and maintenance costs are relatively high; 2. The track structure of a light vehicle is difficult to achieve flexible steering movements on rugged roads, so it is difficult to apply on small carrier platforms in industrial or agricultural fields; 3. The steering control of the tracked vehicle depends on the differential speed of the left and right tracks. If the same control method is directly used on a four-wheeled vehicle, the torque resistance between the front and rear wheel groups will be too large, making it impossible to achieve steering action. 4. The actual effect of the tracked vehicle differential steering control is greatly affected by the flatness of the ground, and it is difficult to accurately estimate the actual steering angle and the time consumed by the steering process. This adds great difficulty to the design of the upper-level control logic.

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

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

[0006] In response to the shortcomings of the existing technology, the present invention provides a four-wheel vehicle steering control system with a minimum turning radius characteristic, which is used to solve the problem of limited movement space in industrial and agricultural fields. It relies on the independent front-wheel steering function to realize a four-wheel vehicle motion control system without internal torque resistance, and the turning radius of the steering control system can reach the minimum turning radius allowed by the structure.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a four-wheel vehicle steering control system with a minimum turning radius characteristic, comprising 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 obtain the steering speed and angle of the four wheels when the four-wheel vehicle is turning. The data processing module then processes and analyzes the steering speed and angle data, and calculates the minimum turning radius using the vehicle steering model. The data output module then outputs the data to the execution module, which controls the steering of the front wheels.

[0008] The vehicle steering model is characterized by the location of the steering center of the four-wheel vehicle, including the external steering center model and the internal steering center model.

[0009] make is the longitudinal length of the vehicle body, It is half of the left and right width of the vehicle body. is the distance between the steering center and 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; angle is the steering angle of the left front wheel, is the steering angle of the right front wheel; is the vehicle's speed control value, is the speed of the left rear wheel, is the speed of the right rear wheel, Left front wheel speed Projection on the rear wheel axis, Right front wheel speed projection on the rear wheel axis;

[0010] In the outboard steering model:

[0011]

[0012] when The minimum movement radius when the steering center is outside the vehicle body is reached. The minimum movement radius is:

[0013] ;

[0014] The steering center is built into the model;

[0015]

[0016] when When the turning center of the vehicle body moves inward to coincide with the longitudinal center line of the vehicle body, the minimum movement radius is:

[0017]

[0018] Preferably, 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 four-wheeled vehicle.

[0019] 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, the speed sensor, and the steering angle sensor.

[0020] Preferably, the execution module includes a wheel driver installed on the four wheels of the four-wheeled vehicle. The wheel driver is controlled and connected to the steering controller of the four-wheeled vehicle. The collected wheel speed and steering angle information are transmitted to the controller via wired or wireless means. The controller integrates the control data sent by the upper-level intelligent control logic, uses the vehicle steering model to process the data, and obtains the steering control amount of the left and right front wheels and the speed control amount of each wheel. The controller transmits the results of these data processing to the wheel driver via wired or wireless communication, and the wheel driver is responsible for completing the speed closed-loop and steering angle closed-loop control logic.

[0021] Preferably, in the vehicle steering model, and is the inherent property of the vehicle body. and It is the control quantity issued by the upper control logic. The main function of the steering control system is to calculate the reasonable 、 、 、 、 and Equal control amount.

[0022] Preferably, in the model with the steering center built in, since the steering center enters the interior of the vehicle body, the turning radius is smaller than that of the steering center located outside the vehicle body. Expressed as the distance between the steering center and the longitudinal center of the vehicle body.

[0023] Preferably, during the steering process, when the steering center enters the interior of the vehicle body, if the same control method as when the steering center is located outside the vehicle body is continued to be used, the turning angle of the left front wheel will be greater than 90 degrees. If the front-wheel steering structure supports this control method, the "steering center external model" will continue to be used for control; if the front-wheel steering structure does not support steering control greater than 90 degrees, the "steering center built-in model" will be used for control.

[0024] Preferably, in the "steering center built-in model", the steering center is located inside the vehicle body. , so the steering angle of the left front wheel is a negative angle, and and are all 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

[0025] It is also a negative value, so in the "steering center built-in model", the steering angles and travel speeds of the left and right front wheels satisfy the relationship of equal magnitude and opposite direction.

[0026] Preferably, in the "steering center built-in model", when the steering center is located to the right of the longitudinal center of the vehicle body, its minimum movement radius is the same as that when the steering center is located to the left of the longitudinal center of the vehicle body.

[0027] Preferably, when the distance between the front wheels of the vehicle is not equal to the distance between the rear wheels or the sizes of the front and rear wheels are different, the width of the vehicle body is based on the width of the front wheels during data processing, and the speed control amount of the rear wheels is scaled proportionally.

[0028] The present invention discloses a steering control system for a four-wheel vehicle with a minimum turning radius characteristic, which has the following beneficial effects:

[0029] 1. The steering control system of the four-wheeled vehicle with the minimum turning radius characteristic calculates the travel speed of the front and rear wheels of the vehicle body, as well as the steering angle of each of the two front wheels, based on the inherent parameters of the four-wheeled vehicle and the combined parameters of the motion control quantity. In this way, the minimum motion radius allowed by the structure is achieved without generating internal torque. The calculation method of each control quantity of the steering control system and the calculation formula of the minimum motion radius that can be achieved under different control modes are clearly given, thereby effectively controlling the vehicle to achieve the minimum motion radius and improving the site adaptability of the four-wheeled vehicle.

[0030] 2. This four-wheel vehicle steering control system with the minimum turning radius characteristic controls the front wheels of the four-wheel vehicle to steer independently, while controlling the speed of each of the four wheels of the four-wheel vehicle, thereby abandoning the bulky differential and steering linkage design of traditional cars. The rear wheels do not need to have steering capabilities. Only two front wheels with relatively independent and relatively simple steering structures are required to achieve flexible steering control. It is more suitable for use in light four-wheel vehicles commonly found in industrial and agricultural fields, and reduces the difficulty of four-wheel vehicle structural design, avoids the use of complex transmission and steering structures, and effectively reduces the production and maintenance costs of the vehicle.

[0031] 3. The steering control system of the four-wheel vehicle with the minimum turning radius characteristic comprehensively designs the front wheel steering angle and the speed control of each wheel, thereby minimizing the generation of internal torque, thereby ensuring the overall reliability of the four-wheel vehicle, effectively avoiding unnecessary energy consumption, and improving the vehicle's working time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is a functional architecture diagram of the four-wheel vehicle steering control system of the present invention;

[0034] Figure 2 This is the overall electrical block diagram of the four-wheel vehicle steering control system of the present invention;

[0035] Figure 3 This is a schematic diagram of the present invention in which the steering center is located outside the vehicle body;

[0036] Figure 4 This is a schematic diagram of the present invention in which the steering center is located inside the vehicle body;

[0037] Figure 5 Schematic diagram of the minimum motion radius of the present invention. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] The embodiments of the present application provide a four-wheel vehicle steering control system with a minimum turning radius characteristic, which is used to solve the problem of limited movement space in industrial and agricultural fields. By relying on the independent front-wheel steering function, a four-wheel vehicle motion control system without internal torque resistance is realized, and the turning radius of the steering control system can reach the minimum turning radius allowed by the structure.

[0040] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0041] An embodiment of the present invention discloses a steering control system for a four-wheel vehicle with a minimum turning radius characteristic.

[0042] According to the attached Figure 1-5As shown, the steering control system requires that the front wheels of the four-wheel vehicle have the ability to steer at a certain angle, and the steering structures of the left and right front wheels are relatively independent. The steering control system converts the control quantities such as the travel speed and turning radius issued by the upper-level application into the travel speed control quantities and front wheel steering angle control quantities of each wheel, and then realizes the vehicle's movement and steering and other motion control functions based on speed closed-loop control and angle closed-loop control. The "travel speed" mentioned here refers to the speed of the vehicle's central axis in the forward direction, and the "turning radius" refers to the distance between the longitudinal center axis of the vehicle and the steering center.

[0043] The left and right front wheel steering in this steering control system adopts an independent steering control structure. Therefore, the left and right front wheels do not need to be connected by a connecting rod or a rotating shaft. Instead, the steering angle of the left and right front wheels is coordinated and controlled by the controller to complete the steering function.

[0044] 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 obtain the steering speed and angle of the four wheels when the four-wheeled vehicle is turning. Then, the data processing module is used to process and analyze the turning speed and angle data, and the minimum turning radius is calculated through the vehicle steering model. Then, the data output module is used to output the data to the execution module, and the execution module is used to control the front wheel steering. The vehicle steering model uses the location of the steering center of the four-wheeled vehicle as a distinguishing feature, including a steering center external model and a steering center internal model.

[0045] 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 four-wheeled vehicle. The data processing module and the vehicle steering model are written into the four-wheeled vehicle steering controller, and real-time data is acquired through the controller, the speed sensor and the steering angle sensor. 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 steering controller of the four-wheeled vehicle. The collected wheel speed and steering angle information are transmitted to the controller via wired or wireless means. The controller integrates the control data sent by the upper-level intelligent control logic, and uses the vehicle steering model to process the data to obtain the steering control amount of the left and right front wheels and the speed control amount of each wheel. The controller transmits the results of these data processing to the wheel driver via wired or wireless communication, and the wheel driver is responsible for completing the speed closed-loop and steering angle closed-loop control logic.

[0046] In order to avoid the internal torque generated by the vehicle's own structure, the four wheels of a four-wheeled vehicle must all move in a circular motion around the same steering center. When the steering center is located outside the vehicle body, the relationship between the wheel's travel speed and steering angle is as follows: Figure 2 As shown;

[0047] in, is the longitudinal length of the vehicle body, It is half of the left and right width of the vehicle body. is the distance between the steering center and 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; angle is the steering angle of the left front wheel, is the steering angle of the right front wheel; is the vehicle's speed control value, is the speed of the left rear wheel, is the speed of the right rear wheel, Left front wheel speed Projection on the rear wheel axis, Right front wheel speed Projection onto the rear wheel axis.

[0048] Among all the above control quantities, and is the inherent property of the vehicle body. and It is the control quantity issued by the upper control logic. The main function of the steering control system is to calculate the reasonable 、 、 、 、 and When the steering center is outside the vehicle body, the relationship between each control variable and the known quantity is as follows:

[0049]

[0050] when The minimum movement radius when the steering center is outside the vehicle body is reached. The minimum movement radius is:

[0051]

[0052] When the steering center enters the interior of the vehicle body, the turning radius is smaller than that of the steering center outside the vehicle body. Figure 3 As shown:

[0053] in, It is the distance between the steering center and the longitudinal center of the vehicle body.

[0054] At this time, if we continue to use the same control method when the steering center is located outside the vehicle body, the turning angle of the left front wheel will be greater than 90 degrees. If the front-wheel steering structure supports this control method, we can continue to use this method for control. If the front-wheel steering structure does not support such a large angle of steering control, in order to achieve a smaller turning radius, we can define different control modes based on the relative position of the steering center and the vehicle body, and then use different calculation methods for different control modes. For example, the steering control mode can be divided into "steering center external model" and "steering center internal model", corresponding to the attached Figure 2 and attached Figure 3 .

[0055] In the "Steering Center Built-in Model" setting, the steering center is located inside the vehicle. The steering angle of the left front wheel is no longer greater than 90 degrees, but becomes negative. The calculation methods for the speed of each wheel and the front wheel steering angle are as follows:

[0056]

[0057] Among them, because under the "turning center built-in model" ,so and are all 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 negative.

[0058] The turning center of the vehicle body continues to move inward until the turning center coincides with the longitudinal center line of the vehicle body, and the movement radius reaches the minimum value, such as Figure 4 As shown:

[0059] Under the "steering center built-in model", the steering angles and travel speeds of the left and right front wheels are equal in magnitude and opposite in direction. The minimum turning radius obtained at this time is:

[0060]

[0061] When the turning center is located to the right of the longitudinal center of the vehicle body, the calculation method is the same as above.

[0062] If the steering angle range of the front wheels cannot reach the maximum angle range allowed by the above control system due to the limitations of the front wheel steering structure, the steering control algorithm is still applicable, but the actual minimum turning radius may be larger than the minimum motion radius mentioned here.

[0063] If the distance between the front wheels and the rear wheels of the vehicle is not equal, or the front and rear wheels are of different sizes, this control system can also be used. During the data processing process, 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 proportionally scaled based on this steering control system to obtain a complete steering motion control amount for this type of vehicle.

[0064] Working principle: The present invention proposes a four-wheel vehicle steering control system with practical use value. The control system can calculate the travel speed of the front and rear wheels of the vehicle body, as well as the steering angle of each of the two front wheels, based on the inherent parameters of the four-wheel vehicle and the combined parameters of the motion control quantity, so as to achieve the minimum motion radius allowed by the structure without generating internal torque. The present invention clearly provides the calculation method of each control quantity of the steering control system and the calculation formula of the minimum motion radius that can be achieved under different control modes.

[0065] At the same time, the present invention proposes a combination method of vehicle motion control quantities that is different from traditional control methods. The control quantity combination method includes the vehicle body travel speed and turning radius. This combination method is suitable for motion control logic oriented towards turning radius, which can effectively reduce the design difficulty of the upper-level intelligent control logic.

[0066] Based on the relative position relationship between the steering center and the vehicle body, the present invention proposes two control mode division methods. Among them, the "steering center built-in model" effectively reduces the steering control system's requirements for the front wheel steering angle range. Under the same physical structure, a smaller turning radius can be achieved, thereby improving the site adaptability of the four-wheel vehicle.

[0067] Compared with traditional automobiles, tracked vehicles and four-wheel steering control methods, the present invention has the following advantages:

[0068] 1. Product Lightweight: Vehicles using this algorithm can abandon the bulky differential and steering linkage design of traditional cars. The rear wheels do not need to have steering capabilities. Only two front wheels with relatively independent and relatively simple steering structures can achieve flexible steering control. This makes it more suitable for light four-wheeled vehicles commonly used in industrial and agricultural fields.

[0069] 2. Relatively low product cost: The present invention reduces the difficulty of structural design of the four-wheel vehicle and avoids the use of complex transmission and steering structures, thereby effectively reducing the production and maintenance costs of the vehicle;

[0070] 3. High product reliability and low power consumption: The present invention comprehensively designs the front wheel steering angle and the speed control of each wheel, thereby minimizing the generation of internal torque, thereby ensuring the overall reliability of the four-wheel vehicle, effectively avoiding unnecessary energy consumption, and increasing the vehicle's working time;

[0071] 4. Quantifiable control effect: Compared with the problem of left and right differential control of tracked vehicles that it is difficult to estimate the actual steering angle and turning radius, the turning radius of this steering control system can be directly calculated, making the steering control effect quantifiable and the vehicle trajectory predictable. It is well adapted to the upper-level intelligent control logic, reducing the design difficulty of the upper-level control logic.

[0072] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A four-wheel vehicle steering control system with a minimum turning radius characteristic, 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 speed and angle of the four wheels when the four-wheel vehicle turns, and then the data processing module is used to process and analyze the steering speed and angle data, and the minimum turning radius is calculated through the vehicle steering model. The data output module is then used to output the data to the execution module, and the execution module is used to control the front wheel steering; The vehicle steering model is characterized by the location of the steering center of the four-wheel vehicle, including the external steering center model and the internal steering center model. Let h be the longitudinal length of the vehicle body, r0 be half of the left and right width of the vehicle body, re be the distance between the steering center and the outer edge of the vehicle body, rA be the turning radius of the left front wheel, rB be the turning radius of the right front wheel; angle α is the steering angle of the left front wheel, β is the steering angle of the right front wheel; V0 is the speed control value of the vehicle body, V l is the speed of the left rear wheel, Vr is the speed of the right rear wheel, VA′ is the speed of the left front wheel V A Projection on the rear wheel axis, VB' is the speed of the right front wheel V B projection on the rear wheel axis; In the outward-steering model: When r e = 0, the minimum movement radius is reached when the steering center is located outside the vehicle body. The minimum movement radius is: The steering center is built into the model; When r e = 0, when the turning center of the vehicle moves inward to coincide with the longitudinal centerline of the vehicle, the minimum movement radius is:

2. A four-wheel vehicle steering control system with minimum turning radius characteristics according to claim 1, characterized in that: 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 of the four-wheel vehicle.

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

4. A four-wheel vehicle steering control system with minimum turning radius characteristics 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 steering controller of the four-wheeled vehicle. The collected wheel speed and steering angle information are transmitted to the controller via wired or wireless means. The controller integrates the control data sent by the upper-level intelligent control logic and uses the vehicle steering model to process the data to obtain the steering control amount of the left and right front wheels and the speed control amount of each wheel. The controller transmits the results of these data processing to the wheel drivers via wired or wireless communication. The wheel drivers are responsible for completing the speed closed-loop and steering angle closed-loop control logic.

5. A four-wheel vehicle steering control system with minimum turning radius characteristics according to claim 1, characterized in that: In the vehicle steering model, h and r0 are the inherent properties of the vehicle body, V0 and re are the control quantities issued by the upper-level control logic. The main function of the steering control system is to calculate reasonable Vι, Vr, VA′, VB′, α and β control quantities based on these known quantities.

6. A four-wheel vehicle steering control system with minimum turning radius characteristics 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, the turning radius is smaller than when the steering center is located outside the vehicle body. At this time, re is expressed as the distance between the steering center and the longitudinal center of the vehicle body.

7. A steering control system for a four-wheeled vehicle with a minimum turning radius characteristic according to claim 6, characterized in that: During the steering process, when the steering center enters the interior of the vehicle body, if the same control method as when the steering center is located outside the vehicle body is continued to be used, the turning 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" will continue to be used for control; if the front-wheel steering structure does not support steering control greater than 90 degrees, the "internal steering center model" will be used for control.

8. A steering control system for a four-wheeled vehicle with a minimum turning radius characteristic according to claim 1, characterized in that: In the "steering center built-in model", the steering center is located inside the vehicle body. e <r0, so the steering angle of the left front wheel is a negative angle, and V l and α are both negative values; and because the left front wheel's rotation direction is opposite to the speed direction, the left front wheel speed VA is also negative. Therefore, in the "steering center built-in model", the steering angles and travel speeds of the left and right front wheels satisfy the relationship of equal magnitude and opposite direction.

9. A steering control system for a four-wheeled vehicle with a minimum turning radius characteristic according to claim 8, characterized in that: In the "Steering Center Built-in Model", when the steering center is located to the right of the vehicle's longitudinal center, its minimum movement radius is the same as when the steering center is located to the left of the vehicle's longitudinal center.

10. A steering control system for a four-wheeled vehicle with a minimum turning radius characteristic according to claim 1, characterized in that: When the distance between the front and rear wheels of the vehicle is 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 data processing, and the speed control amount of the rear wheels is scaled proportionally.

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