Compass steering control method for unmanned inspection vehicle and unmanned inspection vehicle

Abstract

The invention discloses a compass steering control method for an unmanned inspection vehicle. The compass steering control method comprises the steps of function starting, function parameter setting, vehicle environment sensing and function execution judgment, wheel target rotating speed optimization and execution. The maneuvering performance of the unmanned inspection vehicle can be effectively improved, the tire sliding speed in the steering process of compasses is reduced, tire abrasion is remarkably reduced, and high maneuverability and operation reliability of the unmanned inspection vehicle in a narrow space are improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle steering and assisted driving technology, and in particular to a compass steering control method for an unmanned inspection vehicle and the unmanned inspection vehicle itself. Background Technology

[0002] With the rapid development of unmanned inspection technology, unmanned inspection vehicles are increasingly widely used in industrial production, facility maintenance, and safety monitoring. In real-world working environments, unmanned inspection vehicles often need to enter narrow, complex, or compact areas to perform inspection tasks, such as inside substations, pipeline corridors, and densely populated areas of factories. These scenarios place extremely high demands on the mobility of the inspection vehicles; the vehicles must have a small turning radius and agile handling capabilities to ensure they can move freely within confined spaces and accurately reach their designated locations.

[0003] However, the commonly used Ackerman steering system, while simple in structure and easy to control, has significant turning radius constraints, with a relatively large minimum turning radius. This results in severely insufficient maneuverability of unmanned inspection vehicles in confined spaces, failing to meet the demands for highly flexible inspections. To improve maneuverability, differential steering has been widely adopted in the field of unmanned inspection vehicles.

[0004] A highly maneuverable steering mode known as compass steering is gaining attention. Compass steering utilizes the independent four-wheel drive capability of unmanned inspection vehicles. Without employing a traditional Ackermann steering mechanism, it achieves precise rotational movement around the locked wheel as the steering center by locking one of the vehicle's four wheels and differentially controlling the remaining three. This steering mode significantly improves the maneuverability of unmanned inspection vehicles in confined spaces and significantly reduces the turning radius, especially demonstrating strong passability when facing narrow right-angle bends.

[0005] While the compass-like turning motion offers high maneuverability, it also leads to intense tire-to-ground friction, resulting in rapid tire wear. This reduces the inspection vehicle's economy and operational reliability, while increasing maintenance costs. Therefore, effectively reducing tire wear, extending tire life, and improving the overall economic efficiency and reliability of the unmanned inspection vehicle during highly maneuverable compass-like turning motions has become a crucial technical challenge that urgently needs to be addressed in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a compass steering control method for an unmanned inspection vehicle and an unmanned inspection vehicle. By solving and tracking the target rotation speed of the non-center wheel, the method can minimize tire wear while ensuring maneuverability.

[0007] To solve the above technical problems, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a compass steering control method for an unmanned inspection vehicle, comprising the following steps:

[0009] Step S1: Ensure the vehicle is in P gear and completely stopped, then activate the compass steering control system.

[0010] Step S2: Set the vehicle's compass steering parameters, including the center wheel, yaw rate, rotation direction, and rotation angle; the rotation direction is clockwise or counterclockwise.

[0011] Step S3: The compass steering control system obtains the ground adhesion coefficient, road slope and obstacle position through the vehicle perception system, and determines whether the compass steering execution conditions are met; if the conditions are not met, the execution ends and the reason for failure to execute is reported; if the conditions are met, step S4 is executed.

[0012] Step S4: Based on the compass steering parameters set in Step 2 and the ground adhesion coefficient, road slope, and obstacle position obtained in Step S3, first set the target rotation speed of the selected center wheel to zero and the longitudinal slip speed of the non-center wheel to be the optimization variable. Then, with minimizing the sum of squares of the longitudinal slip speeds of the non-center wheels as the optimization objective, construct the optimization objective function and constraints. Finally, use the interior point method to optimize and solve the problem to determine the optimal target rotation speed of the non-center wheels.

[0013] Step S5: Use four controllers to track and control the rotation speed of the four wheels respectively until the rotation speed of the non-center wheel reaches the optimal target speed determined in step S4. When the vehicle's rotation angle reaches the preset value in step S2, reset the target speed of all wheels to zero, so as to realize the unmanned inspection vehicle's compass-like steering with the center wheel as the rotation center.

[0014] Secondly, an unmanned inspection vehicle is provided, including a vehicle body and four independent drive wheels located at the bottom of the vehicle body. The vehicle also integrates a perception system, a controller, and a compass steering control system for executing the compass steering control method of the unmanned inspection vehicle.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts a compass steering motion mode on a four-wheel independently driven unmanned inspection vehicle, enabling the vehicle to rotate in place or nearly in place with a single wheel as the steering center, significantly reducing the turning radius and greatly improving the maneuverability and passability of the unmanned inspection vehicle in narrow, complex and compact environments; on this basis, the present invention further addresses the problem of severe tire slippage and excessive wear during the existing compass steering process by optimizing the control of the compass steering motion, effectively reducing the ineffective slippage and friction intensity between the tire and the ground, thereby significantly slowing down tire wear, extending tire life, improving the stability, reliability and overall operational economy of the vehicle, and without adding complex mechanical structures, it has good engineering feasibility and promotional application value. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the compass steering control method for the unmanned inspection vehicle of the present invention.

[0018] Figure 2 This is a schematic diagram of four steering motion modes of the compass steering control method for the unmanned inspection vehicle of the present invention;

[0019] in, Figure 2 (a) is a schematic diagram of the wheel turning counterclockwise with the left front wheel as the center;

[0020] Figure 2 (b) is a schematic diagram of the wheel turning counterclockwise with the right front wheel as the center;

[0021] Figure 2 (c) is a schematic diagram of the wheel turning counterclockwise with the left rear wheel as the center;

[0022] Figure 2 (d) is a schematic diagram of the wheel turning counterclockwise with the right rear wheel as the center;

[0023] Figure 2 (e) is a schematic diagram of the clockwise rotation of the wheel with the left front wheel as the center;

[0024] Figure 2 (f) is a schematic diagram of the clockwise rotation of the wheel with the right front wheel as the center;

[0025] Figure 2(g) is a schematic diagram of the clockwise rotation of the wheel with the left rear wheel as the center;

[0026] Figure 2 (h) is a diagram showing the clockwise rotation of the wheel with the right rear wheel as the center. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. The terminal technical solutions of the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1-2 As shown, this invention provides a compass steering control method for unmanned inspection vehicles, applicable to unmanned inspection vehicles with four-wheel independent drive capability but without an Ackermann steering mechanism. When the vehicle needs to perform a stationary turning task, especially in space-constrained environments, the compass steering control mode is activated, enabling high-maneuverability steering with any one wheel as the center and the other three wheels rotating differentially in coordination. The method includes the following steps:

[0029] Step S1: Activate the function. Ensure the vehicle is in P gear and completely stopped, then activate the compass steering control system.

[0030] Step S2: Function Parameter Setting. Set the vehicle's compass steering parameters via the central control interface, including the center wheel and wheel number. Corresponding to the left front wheel, right front wheel, left rear wheel, and right rear wheel respectively; yaw rate The unit is Rotation direction and rotation angle The unit is The direction of rotation includes clockwise or counterclockwise.

[0031] Step S3: Vehicle Environmental Perception and Function Execution Judgment. The compass steering control system obtains the ground adhesion coefficient through the vehicle perception system. Road slope The system detects the location of obstacles around the vehicle and determines whether the conditions for compass steering are met. If the conditions are not met, the execution ends, and the reason for the failure is reported. If the conditions are met, step S4 is executed. The conditions that are not met include a road surface adhesion coefficient greater than 1.0, a road slope greater than 2% or less than -2%, and the presence of obstacles within the movement area.

[0032] Step S4: Optimize the target rotation speed of the wheels. Based on the compass steering parameters set in Step 2 and the ground adhesion coefficient, road slope and obstacle position obtained in Step S3, the target rotation speed of the selected center wheel is first set to zero, and the longitudinal slip speed of the non-center wheel is set as the optimization variable. Then, with minimizing the sum of the squares of the longitudinal slip speeds of the non-center wheels as the optimization objective, the optimization objective function and constraints are constructed. Finally, the interior point method is used to optimize and solve the problem to determine the optimal target rotation speed of the non-center wheels. The constraints are: (1) During the steady-state compass steering process, the total torque generated by the non-center wheels around the center wheel is zero; (2) The force on the center wheel cannot exceed its adhesion limit.

[0033] Because the unmanned inspection vehicle has a stable load and similar vertical loads on all four wheels, tire wear mainly depends on the slip speed. The unmanned inspection vehicle lacks a steering mechanism; the four wheels have fixed directions, and the sideslip angle is constant during circular steering. Therefore, the lateral slip speed is constant. In this embodiment, the optimization control objective is to minimize the sum of the squares of the longitudinal slip speeds of the three non-central wheels. The longitudinal slip speed of the wheels is... .

[0034] When the selected center wheel is the left front wheel, the optimization objective function is expressed as follows:

[0035]

[0036] in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel;

[0037] The torque balance constraints are as follows:

[0038]

[0039] in, The longitudinal force on the right front tire. The longitudinal force is on the right rear tire. The lateral force is from the left rear tire. The lateral force is from the right rear tire. The wheelbase is the distance between the wheels. Given the wheelbase, and considering that the left and right rear wheels are in a state of complete slippage while the right front wheel is in a state of pure longitudinal slippage, we can derive the following from the magic tire formula and the combined working condition formula:

[0040]

[0041] ,

[0042] ,

[0043] in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the left rear tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right front wheel, and , The longitudinal slip speed of the right front wheel. The longitudinal speed of the right front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel. The lateral slip velocity of the left rear wheel, and , The lateral slip velocity of the right rear wheel, and , This is the maximum tire force;

[0044] The adhesion limit constraints of the circular wheel are as follows:

[0045]

[0046] in, The longitudinal force on the left front tire. ; The lateral force of the left front tire. , This represents the maximum tire force.

[0047] When the selected center wheel is the right front wheel, the optimization objective function is expressed as follows:

[0048]

[0049] in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel;

[0050] The torque balance constraints are as follows:

[0051]

[0052] in, The longitudinal force on the left front tire. The longitudinal force on the left rear tire. The lateral force is from the left rear tire. The lateral force is from the right rear tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left and right rear wheels are in a state of complete slippage, while the left front wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula:

[0053]

[0054] ,

[0055] ,

[0056] in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force is on the right rear tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the left front wheel, and , The longitudinal slip speed of the left front wheel. The longitudinal speed of the left front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel. The lateral slip velocity of the left rear wheel, and , The lateral slip velocity of the right rear wheel, and , This is the maximum tire force;

[0057] The adhesion limit constraints of the circular wheel are as follows:

[0058]

[0059] in, The longitudinal force on the right front tire. ; The lateral force of the right front tire. , This represents the maximum tire force.

[0060] When the selected center wheel is the left rear wheel, the optimization objective function is expressed as follows:

[0061]

[0062] in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip speed of the right rear wheel;

[0063] The torque balance constraints are as follows:

[0064]

[0065] in, The longitudinal force on the right front tire. The longitudinal force is on the right rear tire. The lateral force of the left front tire. The lateral force of the right front tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left and right front wheels are in a state of complete slippage, while the right rear wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula:

[0066]

[0067] ,

[0068] ,

[0069] in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the left front tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right rear wheel, and , The longitudinal slip speed of the right rear wheel. The longitudinal speed of the right rear wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The lateral slip velocity of the left front wheel, and , The lateral slip velocity of the right front wheel, and , This is the maximum tire force;

[0070] The adhesion limit constraints of the circular wheel are as follows:

[0071]

[0072] in, The longitudinal force on the left rear tire. ; The lateral force is from the left rear tire. , This represents the maximum tire force.

[0073] When the selected center wheel is the right rear wheel, the optimization objective function is expressed as follows:

[0074]

[0075] in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip speed of the left rear wheel;

[0076] The torque balance constraints are as follows:

[0077]

[0078] in, The longitudinal force on the left front tire. The longitudinal force on the left rear tire. The lateral force of the left front tire. The lateral force of the right front tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left front wheel and right front wheel are in a state of complete slippage, while the left rear wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula:

[0079]

[0080] ,

[0081] ,

[0082] in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the right front tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right rear wheel, and , The longitudinal slip velocity of the left rear wheel. The longitudinal speed of the left rear wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The lateral slip velocity of the left front wheel, and , The lateral slip velocity of the right front wheel, and , This is the maximum tire force;

[0083] The adhesion limit constraints of the circular wheel are as follows:

[0084]

[0085] in, The longitudinal force is on the right rear tire. ; The lateral force is from the right rear tire. , This represents the maximum tire force.

[0086] The optimization solution process using the interior point method is as follows:

[0087] (1) Construct a potential function based on the optimization objective to transform the restricted optimization problem into an unconstrained or simply constrained problem in the form of a potential function, as shown in the following expression:

[0088]

[0089] in, Let be the potential function. The obstacle coefficient, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The number of constraints. Represents all constraint expressions; The longitudinal slip velocity of the non-centered wheel;

[0090] (2) Initialization: Set the initial solution Obstacle parameters Termination threshold ;

[0091] (3) Newton direction iteration: in each iteration k In the middle, calculate the gradient and Hessian matrix:

[0092]

[0093] (4) Step size update: ;in, The step size is determined by the line search method;

[0094] (5) Barrier parameter attenuation: ;in, The attenuation coefficient is, and ;

[0095] (6) Repeat the iteration until the termination condition is met. Convergence complete, outputting the longitudinal slip velocity of the non-circular wheel. The optimal solution.

[0096] Based on the longitudinal slip speed of the non-centered wheel The optimal solution is to calculate the optimal target speed of the non-circular wheel, including:

[0097] (1) When the left front wheel is the center wheel, The optimal target speed for each wheel is: , , , ;

[0098] (2) When the right front wheel is the center wheel, The optimal target speed for each wheel is: , , , ;

[0099] (3) When the left rear wheel is the center wheel, The optimal target speed for each wheel is: , , , ;

[0100] (4) When the right rear wheel is the center wheel, The optimal target speed for each wheel is: , , , ;

[0101] in, These are the optimal target speeds for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. These are the longitudinal slip speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The yaw rate is angular velocity. The wheelbase is the distance between the wheels. The radius is the wheel radius.

[0102] Step S5: Execute the function. Four PI controllers are used to track and control the rotational speed of the four wheels respectively, until the rotational speed of the three non-central wheels reaches the optimal target speed determined in step S4, and when the vehicle's rotation angle reaches the preset value in step S2. Then, the target rotation speed of all wheels is reduced to zero, enabling the unmanned inspection vehicle to turn in a compass-like manner with the central wheel as the center of rotation.

[0103] The current rotational speed of the wheels is collected, and the error between it and the optimal target rotational speed is calculated. Then, the output is used to drive the motor to adjust the torque of each wheel, realizing closed-loop tracking control of the optimal target rotational speed of non-centered wheels. The formula is as follows:

[0104]

[0105] in, For wheel torque, For PID proportional parameters, The optimal target speed for the wheels. for The wheel speed at any given moment, These are the integral parameters for the PID controller.

[0106] During the vehicle's compass-like steering process, the rotation angle accumulates, and when the preset vehicle rotation angle is reached... Then, the system sets the target speed of all wheels to zero, bringing the vehicle to a smooth stop.

[0107] The present invention also provides an unmanned inspection vehicle, including a vehicle body and four independent drive wheels disposed at the bottom of the vehicle body. The vehicle also integrates a sensing system, a controller, and a compass steering control system for executing the unmanned inspection vehicle compass steering control method.

[0108] All parts not covered in this invention are the same as or implemented using existing technologies.

[0109] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A compass steering control method for an unmanned inspection vehicle, characterized in that: Includes the following steps: Step S1: Ensure the vehicle is in P gear and completely stopped, then activate the compass steering control system; Step S2: Set the vehicle's compass steering parameters, including the center wheel, yaw rate, rotation direction, and rotation angle; the rotation direction is clockwise or counterclockwise. Step S3: The compass steering control system obtains the ground adhesion coefficient, road slope and obstacle position through the vehicle perception system, and determines whether the compass steering execution conditions are met; If the conditions are not met, the execution ends and the reason for the failure is reported; if the conditions are met, step S4 is executed. Step S4: Based on the compass steering parameters set in Step 2 and the ground adhesion coefficient, road slope and obstacle position obtained in Step S3, first set the target speed of the selected center wheel to zero and the longitudinal slip speed of the non-center wheel to the optimization variable. Then, with minimizing the sum of squares of the longitudinal slip speeds of the non-center wheels as the optimization objective, construct the optimization objective function and constraints. Finally, use the interior point method to optimize and solve the problem to determine the optimal target speed of the non-center wheels. Step S5: Use four controllers to track and control the rotation speed of the four wheels respectively until the rotation speed of the non-center wheel reaches the optimal target speed determined in step S4. When the vehicle's rotation angle reaches the preset value in step S2, reset the target speed of all wheels to zero, so as to realize the unmanned inspection vehicle's compass-like steering with the center wheel as the rotation center.

2. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, the constraint condition is: (1) The sum of the torques generated by the non-central wheel around the central wheel is zero; (2) The force on the central wheel cannot exceed its adhesion limit.

3. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, when the selected center wheel is the left front wheel, the objective function is optimized as follows: in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel; The torque balance constraints are as follows: in, The longitudinal force on the right front tire. The longitudinal force is on the right rear tire. The lateral force is from the left rear tire. The lateral force is from the right rear tire. The wheelbase is the distance between the wheels. Given the wheelbase, and considering that the left and right rear wheels are in a state of complete slippage while the right front wheel is in a state of pure longitudinal slippage, we can derive the following from the magic tire formula and the combined working condition formula: ， ， in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the left rear tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right front wheel, and , The longitudinal slip speed of the right front wheel. The longitudinal speed of the right front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel. The lateral slip velocity of the left rear wheel, and , The lateral slip velocity of the right rear wheel, and , This is the maximum tire force; The adhesion limit constraints of the circular wheel are as follows: in, The longitudinal force on the left front tire. ; The lateral force of the left front tire. , This represents the maximum tire force.

4. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, when the selected center wheel is the right front wheel, the objective function is optimized as follows: in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel; The torque balance constraints are as follows: in, The longitudinal force on the left front tire. The longitudinal force on the left rear tire. The lateral force is from the left rear tire. The lateral force is from the right rear tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left and right rear wheels are in a state of complete slippage, while the left front wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula: ， ， in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force is on the right rear tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the left front wheel, and , The longitudinal slip speed of the left front wheel. The longitudinal speed of the left front wheel. The longitudinal slip velocity of the left rear wheel. The longitudinal slip speed of the right rear wheel. The lateral slip velocity of the left rear wheel, and , The lateral slip velocity of the right rear wheel, and , This is the maximum tire force; The adhesion limit constraints of the circular wheel are as follows: in, The longitudinal force on the right front tire. ; The lateral force of the right front tire. , This represents the maximum tire force.

5. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, when the selected center wheel is the left rear wheel, the objective function is optimized as follows: in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip speed of the right rear wheel; The torque balance constraints are as follows: in, The longitudinal force on the right front tire. The longitudinal force is on the right rear tire. The lateral force of the left front tire. The lateral force of the right front tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left and right front wheels are in a state of complete slippage, while the right rear wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula: ， ， in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the left front tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right rear wheel, and , The longitudinal slip speed of the right rear wheel. The longitudinal speed of the right rear wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The lateral slip velocity of the left front wheel, and , The lateral slip velocity of the right front wheel, and , This is the maximum tire force; The adhesion limit constraints of the circular wheel are as follows: in, The longitudinal force on the left rear tire. ; The lateral force is from the left rear tire. , This represents the maximum tire force.

6. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, when the selected center wheel is the right rear wheel, the objective function is optimized as follows: in, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The longitudinal slip speed of the left rear wheel; The torque balance constraints are as follows: in, The longitudinal force on the left front tire. The longitudinal force on the left rear tire. The lateral force of the left front tire. The lateral force of the right front tire. The wheelbase is the distance between the wheels. Given the wheelbase, and since the left front wheel and right front wheel are in a state of complete slippage, while the left rear wheel is in a state of pure longitudinal slippage, we can obtain the following from the magic tire formula and the combined working condition formula: ， ， in, As the peak factor, The ground adhesion coefficient, and The correlation coefficient is... The vertical force of the tire. The longitudinal force on the right front tire. For shape factor, Stiffness factor For curvature factor, The longitudinal slip ratio of the right rear wheel, and , The longitudinal slip velocity of the left rear wheel. The longitudinal speed of the left rear wheel. The longitudinal slip speed of the left front wheel. The longitudinal slip speed of the right front wheel. The lateral slip velocity of the left front wheel, and , The lateral slip velocity of the right front wheel, and , This is the maximum tire force; The adhesion limit constraints of the circular wheel are as follows: in, The longitudinal force is on the right rear tire. ; The lateral force is from the right rear tire. , This represents the maximum tire force.

7. The compass steering control method for an unmanned inspection vehicle according to claim 1, characterized in that: In step 4, the process of optimizing the solution using the interior point method is as follows: (1) Construct the potential function based on the optimization objective, as shown in the following expression: in, Let be the potential function. The obstacle coefficient, The sum of the squares of the longitudinal slip velocity of the non-circular wheel. The number of constraints. Represents all constraint expressions; The longitudinal slip velocity of the non-centered wheel; (2) Initialization: Set the initial solution Obstacle parameters Termination threshold ; (3) Newton direction iteration: in each iteration k In the middle, calculate the gradient and Hessian matrix: (4) Step size update: ;in, The step size is determined by the line search method; (5) Barrier parameter attenuation: ;in, The attenuation coefficient is, and ; (6) Repeat the iteration until the termination condition is met. Convergence complete, outputting the longitudinal slip velocity of the non-circular wheel. The optimal solution.

8. The compass steering control method for an unmanned inspection vehicle according to claim 7, characterized in that: In step 4, the optimal target rotational speed of the non-centered wheel is determined according to... The optimal solution is calculated as follows: (1) When the left front wheel is the center wheel, The optimal target speed for each wheel is: , , , ; (2) When the right front wheel is the center wheel, The optimal target speed for each wheel is: , , , ; (3) When the left rear wheel is the center wheel, The optimal target speed for each wheel is: , , , ; (4) When the right rear wheel is the center wheel, The optimal target speed for each wheel is: , , , ; in, These are the optimal target speeds for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. These are the longitudinal slip speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The yaw rate is angular velocity. The wheelbase is the distance between the wheels. The radius is the wheel radius.

9. The compass steering control method for an unmanned inspection vehicle according to claim 7, characterized in that: Step 5 also includes acquiring the current rotational speed of the wheels, calculating the error between it and the optimal target rotational speed, and then outputting the result to drive the motor to adjust the torque of each wheel, thereby achieving closed-loop tracking control of the optimal target rotational speed of the non-centered wheels. The formula is as follows: in, For wheel torque, For PID proportional parameters, The optimal target speed for the wheels. for The wheel speed at any given moment, These are the integral parameters for the PID controller.

10. An unmanned inspection vehicle, comprising a body and four independent drive wheels disposed at the bottom of the body, characterized in that: The vehicle also integrates a sensing system, a controller, and a compass steering control system that executes the compass steering control method for an unmanned inspection vehicle as described in any one of claims 1-9.

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