Dual-mode steering collaborative control method and system for a five-axis heavy-load AGV

Abstract

The present invention discloses a dual-mode steering cooperative control method and system for a five-axis heavy-load AGV. The method includes the following steps: obtaining the state information of the five-axis heavy-load AGV, including vehicle speed, path trajectory curvature, and obstacle distance; determining the scene working condition according to the obtained state information, making a decision on the steering mode of the five-axis heavy-load AGV according to the scene working condition, and sending a steering mode switching command to the underlying controller; the steering mode includes an in-place steering mode and a rear-wheel active coordinated steering mode; the underlying controller is used to control the hub motors and steering motors; the underlying controller calculates the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode, generates motion parameters; converts the motion parameters into reference control quantities and sends them to the underlying controller, and the underlying controller uses IMU feedback and PID control methods to adjust the corresponding motor speeds in real time to drive the five-axis heavy-load AGV to perform steering motion coordinated control.

Description

Technical Field

[0001] The present invention belongs to the field of automatic guided vehicle (AGV) control, and particularly relates to a dual-mode steering cooperative control method and system for a five-axis heavy-duty AGV, which is suitable for the motion control of multi-axis vehicles integrating an in-place steering mode and a rear-wheel active cooperative steering mode. Background Art

[0002] Due to the harsh environment inside a roll-on / roll-off (RoRo) ship and the narrow space for vehicle stacking, there are high precision requirements for transfer vehicles. Therefore, using automatic guided vehicles (AGVs) to replace manual cargo transfer has gradually become the mainstream, which is of great significance for building a green and intelligent unmanned port.

[0003] The current technology has the following defects that need to be solved urgently:

[0004] 1. Structure redundancy problem: The existing in-place steering technology generally adopts a full-wheel independent steering architecture, resulting in the need to configure high-precision steering motors for each wheel group, increasing the system mass by more than 28% and significantly rising the manufacturing cost.

[0005] 2. Mechanical coupling defect: Due to the special requirements of the RoRo ship climbing condition, the rear wheels need to integrate a large-torque drive unit (load ratio > 60%). When the front-wheel active steering mode is adopted, it is easy to cause yaw moment imbalance in the medium and low speed range (0.5 - 5 m / s), resulting in a trajectory tracking error exceeding 15 mm.

[0006] 3. Lack of intelligent decision-making: The existing system lacks a scenario adaptive decision-making logic and relies on manual intervention operations in different steering scenario requirements. Summary of the Invention

[0007] In order to solve the technical problems in the prior art, such as the complex structure and high cost of the multi-wheel independent steering mechanism, easy yaw moment imbalance, large trajectory tracking error, and rough steering mode switching logic, the present invention provides a dual-mode steering cooperative control method for a five-axis heavy-duty AGV. Through an Ackermann geometry correction model, a differential drive kinematics model, a five-axis wheel differential cooperative control, and a scenario decision-making method, the in-place steering function in low-speed scenarios and the low-slip motion control in medium and high-speed scenarios are realized.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] As a first aspect of the present invention, a dual-mode steering cooperative control method for a five-axis heavy-duty AGV is provided. The five-axis heavy-duty AGV has a five-axis and ten-wheel structure. The first, second, third, and fourth axes of the five-axis heavy-duty AGV are all front axes. The first to fourth axes adopt fixed-direction wheels and are independently driven by separate hub motors respectively. The fifth axis of the five-axis heavy-duty AGV is the rear axis, and the fifth axis is equipped with a steering motor for driving the rear wheels to adjust the steering angle. The dual-mode steering cooperative control method is characterized by the following steps:

[0010] S1. Obtain the state information of the five-axis heavy-duty AGV, including vehicle speed v, path trajectory curvature k, and obstacle distance d;

[0011] S2. According to the state information obtained in step S1, determine the scenario working condition, decide the steering mode of the five-axis heavy-duty AGV according to the scenario working condition, and send a steering mode switching command to the underlying controller. The steering modes include in-situ steering mode and rear-wheel active coordinated steering mode. The underlying controller is used to control the hub motor and the steering motor;

[0012] S3. The underlying controller calculates the required linear velocity and angular velocity of each wheel of the five-axis heavy-duty AGV in the corresponding steering mode according to the steering mode switching command sent in step S2 and the path trajectory curvature information of the path planned in step 1, and generates motion parameters;

[0013] S4. Convert the motion parameters generated in step S3 into reference control quantities and send them to the underlying controller. The underlying controller uses IMU feedback and PID control methods to adjust the corresponding motor speeds in real time to drive the five-axis heavy-duty AGV for steering motion coordinated control.

[0014] Further, step S2 includes:

[0015] S21. Perform information fusion on the vehicle speed v and the path trajectory curvature k to determine the scenario working condition of the five-axis heavy-duty AGV. The scenario working conditions include low-speed scenario working conditions and medium-high-speed scenario working conditions;

[0016] S22. Make a decision on the steering mode of the five-axis heavy-duty AGV:

[0017] If the five-axis heavy-duty AGV is in a low-speed scenario working condition, it is decided that the five-axis heavy-duty AGV enters the in-situ steering mode, and an in-situ steering mode switching command is sent to the underlying controller;

[0018] If the five-axis heavy-duty AGV is in a medium-high-speed scenario working condition, it is decided that the five-axis heavy-duty AGV enters the rear-wheel active coordinated steering mode, and a rear-wheel active coordinated steering mode switching command is sent to the underlying controller;

[0019] When the distance d to the obstacle is less than the safety threshold, it is decided that the five-axis heavy-load AGV enters the active rear-wheel collaborative steering mode and sends a command to switch to the active rear-wheel collaborative steering mode to the lower-level controller.

[0020] Further, the scenario condition determination in step S21 is as follows:

[0021] When the vehicle speed v < 0.5 m / s and the path curvature κ > 1.0 m -1 , the five-axis heavy-load AGV is in a low-speed scenario condition;

[0022] When the vehicle speed 0.5 m / s < v 5.6 m / s (20 km / h) and the path curvature κ < 1.0 m -1 , the five-axis heavy-load AGV is in a medium-high speed scenario.

[0023] Further, in step S3, when the lower-level controller receives the in-situ steering mode switching command, the motion parameter calculation process is as follows:

[0024] Set the steering angle of the fifth-axis wheel of the five-axis heavy-load AGV to 0°;

[0025] Set the in-situ steering yaw angular velocity ω to 0.3 rad / s;

[0026] According to the path steering direction of the planned path, set the wheels close to the path direction to rotate forward and the wheels away from the path steering direction to rotate backward;

[0027] The speed v of the wheel close to the steering direction neari = , the speed v away from the steering direction fari =- , where i represents the i-th axis of the five-axis heavy-load AGV and W represents the coaxial wheelbase;

[0028] Calculate the angular velocity ω of each wheel i = 2Vi / W, and then convert the speed to the motor speed n i , and send an execution command to the lower-level controller;

[0029] Verify the centroid movement of the five-axis heavy-load AGV at this time through speed field synthesis. The verification formula is:

[0030] Translation balance verification: ;

[0031] Rotation balance verification:

[0032] Among them, is the wheel speed, refers to the position vector between the centroid and the moving point, and the equivalent moment of inertia I = , W represents the coaxial track width; when a certain wheel fails, the compensated wheel speed output of its coaxial wheels maintains the total angular momentum unchanged.

[0033] Further, in the step S3,

[0034] When the lower-level controller receives the command for switching the rear-wheel active cooperative steering mode, the motion parameter calculation process is as follows:

[0035] According to the Ackermann steering principle, the rear-wheel steering angle δ is obtained from the total wheelbase L, the track width W, and the current minimum turning radius R; the minimum turning radius R is represented by the current path curvature κ, R = 1 / κ; meanwhile, the track width W is ignored;

[0036] The rear-wheel steering angle calculation formula is simplified to:

[0037]

[0038] In the formula, L is the total wheelbase, and κ is the current path curvature;

[0039] The cubic term correction formula δ' = δ + kδ³ is introduced

[0040] In the formula, k is the slip suppression coefficient; thus, the rear-wheel turning angle δ' is obtained;

[0041] The vehicle speeds of other drive wheels are dynamically allocated according to their distances to the steering center O:

[0042] For the outer wheel, = (1 + di*κ);

[0043] For the inner wheel, = (1 - di*κ)

[0044] Wherein, is the lateral offset of the i-th wheel from the steering center O, κ is the curvature radius of the current path, is the wheel speed, is the reference vehicle speed, and R is the theoretical turning radius.

[0045] Further, in the step S4, the motor speed is obtained in real time by using the motor sensor and the IMU and fed back to the lower-level controller. The lower-level controller uses the PID control method to adjust the P and I parameters before mass production of the product, and adjusts the hub motor speed and the steering motor speed according to the hub motor speed difference and the rear-wheel turning angle difference Δδ, so that the control quantity tracks the reference control quantity.

[0046] As the second aspect of the present invention, a dual-mode steering cooperative control system for a five-axis heavy-duty AGV is provided, which is used to implement the dual-mode steering cooperative control method described in the present invention. The dual-mode steering cooperative control system includes:

[0047] A status information detection module, which is used to obtain the status information of the five-axis heavy-load AGV, including vehicle speed v, path trajectory curvature k, and obstacle distance d;

[0048] A decision-making module, which is used to determine the scene working conditions according to the status information of the five-axis heavy-load AGV, make a decision on the steering mode of the five-axis heavy-load AGV according to the scene working conditions, and send a steering mode switching command to the underlying controller;

[0049] The underlying controller is used to calculate the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode according to the received steering mode switching command and the status information of the five-axis heavy-load AGV, generate motion parameters as reference control quantities, and adjust the rotational speeds of the steering motor and the hub motor to achieve coordinated steering motion control.

[0050] Further, the status information detection module includes:

[0051] A hub motor encoder, which is used to obtain the vehicle speed of the five-axis heavy-load AGV in real time;

[0052] A path planning module, which is used to output a planned path and obtain the path trajectory curvature;

[0053] An obstacle perception module, which is used to detect the obstacle distance.

[0054] Further, the underlying controller includes a motion calculation module, which is used to calculate the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode and generate motion parameters.

[0055] Compared with the prior art, the technical effects and advantages of the present invention are:

[0056] In view of the requirements for steering motion control effect and steering function cost, etc., the present invention provides a dual-mode steering cooperative control method for a five-axis heavy-load AGV, which can switch the steering motion control mode according to the current scene of the vehicle, and use different motion control algorithms to achieve the in-situ steering function and requirements in the stationary (extremely low speed) scene. In the medium and low speed scene, the active rear-wheel cooperative steering function is used to achieve steering at small curvatures, reducing the lateral error. At the same time, this method reduces the number of steering motors, saves manufacturing costs and transportation costs, and meets the requirements of green intelligence in port transportation in China. Description of the Drawings

[0057] Figure 1 It is a schematic structural diagram of the five-axis heavy-load AGV described in Embodiment 1 of the present invention;

[0058] Figure 2 It is a flow chart of the dual-mode steering cooperative control method for the five-axis heavy-load AGV described in Embodiment 1 of the present invention;

[0059] Figure 3 It is the kinematic model of the in-situ steering mode described in Embodiment 1 of the present invention;

[0060] Figure 4 It is the kinematic model of the active cooperative steering mode described in Embodiment 1 of the present invention;

[0061] Figure 5 It is the principle block diagram of the dual-mode steering cooperative control system of a five-axis heavy-duty AGV described in Embodiment 2 of the present invention;

[0062] In the figure:

[0063] 1 - The first axis; 2 - The second axis; 3 - The third axis; 4 - The fourth axis; 5 - The fifth axis; 6 - The hub motor; 7 - The steering motor; 8 - The rear wheel; 9 - The clamping mechanism. Specific embodiments

[0064] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0065] Embodiment 1

[0066] This embodiment is a dual-mode steering cooperative control method for a five-axis heavy-duty AGV. The five-axis heavy-duty AGV has a five-axis and ten-wheel structure, and all ten wheels are hub motors that can independently control torque; the first, second, third, and fourth axes 1-4 of the five-axis heavy-duty AGV are all front axes, and the first to fourth axes adopt fixed-direction wheels, and the first to fourth axes are respectively independently driven by separate hub motors 6; the fifth axis 5 of the five-axis heavy-duty AGV is the rear axis, and the fifth axis is equipped with a steering motor 7 to drive the rear wheel 8 to achieve steering angle δ adjustment, increasing the reliability of the five-axis heavy-duty AGV during steering and preventing excessive trajectory tracking errors and lateral slippage;

[0067] The specific operation steps of the method are as follows:

[0068] S1. Obtain the status information of the five-axis heavy-duty AGV:

[0069] Obtain the status information of the five-axis heavy-duty AGV through the status information detection module built in the five-axis heavy-duty AGV, specifically including: obtaining the vehicle speed v (m / s) in real time by the hub motor encoder, outputting the planned path by the path planning module and obtaining the path trajectory curvature k (m -1 ), and detecting the obstacle distance d (m) by the obstacle perception module; in this embodiment, the safety threshold of the obstacle in the obstacle perception module is set to 2 m.

[0070] S2. Based on the status information obtained in step S1, the decision-making module determines the scene working conditions, and based on the scene working conditions, decides the steering mode of the five-axis heavy-load AGV, and sends a steering mode switching command to the underlying controller; the steering mode includes an in-situ steering mode and a rear-wheel active coordinated steering mode; the underlying controller is used to control the hub motor 6 and the steering motor 7;

[0071] S21. The decision-making module fuses the vehicle speed v and the path trajectory curvature k to determine the scene working conditions of the five-axis heavy-load AGV, including:

[0072] When the vehicle speed v < 0.5 m / s and the path curvature κ > 1.0 m -1 , then the five-axis heavy-load AGV is in a low-speed scene working condition;

[0073] When the vehicle speed 0.5 m / s < v 5.6 m / s (20 km / h) and the path curvature κ < 1.0 m -1 , then the five-axis heavy-load AGV is in a medium-high speed scene;

[0074] S22. If the five-axis heavy-load AGV is in a low-speed scene working condition, the decision-making module decides that the five-axis heavy-load AGV enters the in-situ steering mode, and the decision-making module sends an in-situ steering mode switching command to the controllers of the hub motor 6 and the steering motor 7 respectively: If the five-axis heavy-load AGV is in a medium-high speed scene working condition, the decision-making module decides that the five-axis heavy-load AGV enters the rear-wheel active coordinated steering mode, and the decision-making module sends a rear-wheel active coordinated steering mode switching command to the controllers of the hub motor 6 and the steering motor 7 respectively; when the obstacle distance d < the safety threshold (2 m in this embodiment), regardless of the current mode, the decision-making module decides that the five-axis heavy-load AGV enters the rear-wheel active coordinated steering mode.

[0075] S3. The underlying controller calculates the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode according to the steering mode switching command sent in step S2 and the path trajectory curvature information of the path planned in step 1, and generates motion parameters;

[0076] S31. When the underlying controller receives the in-situ steering mode switching command, the calculation process of the motion calculation module is as follows:

[0077] First, set the steering angle of the fifth-axis wheel to 0°, and since the current speed is extremely low, the speed is approximately 0;

[0078] Set the in-situ steering yaw angular velocity ω to 0.3 rad / s;

[0079] According to the path steering direction of the planned path, set the wheel close to the path direction to rotate forward, and set the wheel far from the path steering direction to rotate in reverse; the speed v close to the steering direction neari = The speed v away from the steering direction fari =- , where i represents the i-th axis of the five-axis heavy-load AGV, and W represents the coaxial wheelbase (m).

[0080] Calculate the angular velocity ω of each wheel i = 2Vi / W, and then convert the speed to the motor speed n i (r / min), and send an execution command to the lower-level controller; due to the very low speed and good road conditions, the influence of tire slip is ignored, and no speed compensation is performed for lateral slip;

[0081] Verify the centroid motion of the five-axis heavy-load AGV at this time through speed field synthesis. The verification formula is:

[0082] (translational balance), (rotational balance)

[0083] where refers to the position vector between the centroid and the moving point. The sum of translational velocities automatically returns to zero, and the equivalent moment of inertia I = , when a certain wheel fails, the compensated wheel speed output of its coaxial wheel maintains the total angular momentum unchanged;

[0084] S32. When the lower-level controller receives the rear-wheel active cooperative steering mode switching command, the calculation process of the motion calculation module is as follows:

[0085] According to the Ackermann steering principle, obtain the rear-wheel steering angle δ from the total wheelbase L, wheelbase W, and the current minimum turning radius R; since the minimum turning radius R is difficult to obtain, the minimum turning radius R is represented by the current path curvature κ, R = 1 / κ; at the same time, the wheelbase W is relatively small compared to the turning radius R and can be ignored;

[0086] Therefore, the rear-wheel steering angle calculation formula is simplified to:

[0087]

[0088] In the formula, L is the total wheelbase, and κ is the current path curvature;

[0089] Also introduce the cubic term correction formula δ' = δ + kδ³ (k = 0.15 is the slip suppression coefficient) to compensate for the tire side slip effect during high-speed steering, and thus obtain the rear-wheel steering angle δ'. It should be noted that since it is rear-wheel active steering, the steering direction and steering angle of the five-axis heavy-load AGV should be in the opposite direction, as Figure 4 shown;

[0090] Since no steering motors are equipped for the wheels of other axes, differential compensation needs to be performed for other wheels. The vehicle speeds of other drive wheels are dynamically allocated according to their distances from the steering center O:

[0091] For the outer wheel, = (1 + di*κ);

[0092] For the inner wheel, = (1 - di*κ)

[0093] Wherein, is the lateral offset of the i-th wheel from the steering center O, κ is the curvature radius of the current path, is the wheel speed, is the reference vehicle speed, and R is the theoretical turning radius. Also, since the theoretical turning radius is difficult to obtain, the offset here is approximately simplified to half of the wheelbase, i.e., W / 2.

[0094] S4. Convert the motion parameters generated in step S3 into reference control quantities. The underlying controller uses IMU feedback and PID control methods to adjust the corresponding motor speeds in real time, driving the five-axis heavy-duty AGV for coordinated steering motion control:

[0095] Use motor sensors and IMU, etc. to obtain the motor speeds in real time and feedback them to the underlying controller. The underlying controller uses the PID control method to adjust parameters such as P and I before mass production of the product. According to the wheel hub motor speed difference and the rear wheel steering angle difference Δδ, adjust the wheel hub motor speed and the steering motor speed so that the control quantity accurately tracks the reference control quantity. When the steering mode is switched, the steering angle command δ undergoes a smooth transition through linear mapping, and the transition time t = 0.5 s to avoid the centroid offset caused by sudden turning.

[0096] Preferably, the five-axis heavy-duty AGV is mainly used for transporting automobiles. The clamping mechanism 9 is used to clamp the automobile to be transported. When clamping, it is centered left and right, and the centroid is located on the center line of the five-axis heavy-duty AGV. However, since the models and types of the clamped automobiles are uncertain, their positions on the center line are undetermined. Due to the special nature of the centroid position, when realizing the in-situ steering function, the five-axis heavy-duty AGV is not affected by the position of the centroid on the center line.

Claims

1. A dual-mode steering collaborative control method for a five-axis heavy-duty AGV. The five-axis heavy-duty AGV has a five-axis and ten-wheel structure. The first, second, third, and fourth axes of the five-axis heavy-duty AGV are all front axes. Fixed-direction wheels are used for the first to fourth axes and are independently driven by separate hub motors respectively. The fifth axis of the five-axis heavy-duty AGV is the rear axis, and a steering motor is equipped on the fifth axis to drive the rear wheels for steering angle adjustment. It is characterized in that, The dual-mode steering cooperative control method includes the following steps: S1. Obtain the state information of the five-axis heavy-load AGV, including vehicle speed v, path trajectory curvature k, and obstacle distance d; S2. Based on the state information obtained in step S1, determine the scene working condition, decide the steering mode of the five-axis heavy-load AGV according to the scene working condition, and send a steering mode switching command to the lower-level controller; the steering mode includes an in-situ steering mode and a rear-wheel active coordinated steering mode; the lower-level controller is used to control the hub motor and the steering motor; S3. The lower-level controller calculates the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode according to the steering mode switching command sent in step S2 and the path trajectory curvature information obtained in step S1, and generates motion parameters; S4. Convert the motion parameters generated in step S3 into reference control quantities and send them to the lower-level controller. The lower-level controller uses IMU feedback and PID control methods to adjust the corresponding motor speeds in real time to drive the five-axis heavy-load AGV for steering motion coordination control.

2. The dual-mode steering collaborative control method for a five-axis heavy-load AGV according to claim 1, wherein, The step S2 includes: S21. Fuse the vehicle speed v and the path trajectory curvature k to determine the scene working condition of the five-axis heavy-load AGV. The scene working condition includes a low-speed scene working condition and a medium-high speed scene working condition; S22. Make a decision on the steering mode of the five-axis heavy-load AGV: If the five-axis heavy-load AGV is in the low-speed scene working condition, it is decided that the five-axis heavy-load AGV enters the in-situ steering mode, and an in-situ steering mode switching command is sent to the lower-level controller; If the five-axis heavy-load AGV is in the medium-high speed scene working condition, it is decided that the five-axis heavy-load AGV enters the rear-wheel active coordinated steering mode, and a rear-wheel active coordinated steering mode switching command is sent to the lower-level controller; When the obstacle distance d < safety threshold, it is decided that the five-axis heavy-load AGV enters the rear-wheel active coordinated steering mode, and a rear-wheel active coordinated steering mode switching command is sent to the lower-level controller.

3. The dual-mode steering cooperative control method for a five-axis heavy-duty AGV according to claim 2, characterized in that, The scene working condition determination condition in step S21 is: When the vehicle speed v < 0.5 m / s and the path curvature κ > 1.0 m -1 , the five-axis heavy-load AGV is in a low-speed scenario working condition; When the vehicle speed 0.5m / s < v < 5.6m / s and the path curvature κ < 1.0m -1 , the five-axis heavy-load AGV is in the medium-high speed scenario.

4. The dual-mode steering collaborative control method for a five-axis heavy-load AGV according to claim 1, characterized in that, In step S3, when the lower-level controller receives the in-situ steering mode switching command, the motion parameter calculation process is: Set the steering angle of the fifth-axis wheel of the five-axis heavy-load AGV to 0°; Set the in-situ steering yaw angular velocity ω to 0.3 rad / s; According to the path steering direction of the planned path, set the wheels close to the path direction to rotate forward, and set the wheels far from the path steering direction to rotate in reverse; Wheel speed near the steering direction Speed away from the steering direction Where i represents the i-th axis of the five-axis heavy-duty AGV, and W represents the wheelbase of the same axis; Calculate the angular velocity ω of each wheel i = 2Vi / W, and then convert the speed to the motor speed n i , and send an execution command to the lower-level controller; Verify the centroid motion of the five-axis heavy-load AGV at this time through velocity field synthesis. The verification formula is: Translation equilibrium verification: Verification of rotational balance: Among them, v i is the wheel speed, refers to the position vector between the centroid and the moving point, and the equivalent moment of inertia W represents the wheelbase of the coaxial wheels; when a certain wheel fails, the compensated wheel speed output of its coaxial wheels maintains the total angular momentum unchanged.

5. The dual-mode steering collaborative control method for a five-axis heavy-load AGV according to claim 1, wherein In step S3, When the lower-level controller receives the rear-wheel active coordinated steering mode switching command, the motion parameter calculation process is: According to the Ackermann steering principle, obtain the rear-wheel steering angle δ from the total wheelbase L, wheel track W, and the current minimum turning radius R; represent the minimum turning radius R with the current path curvature κ, R = 1 / κ; at the same time, ignore the wheel track W; The rear-wheel steering angle calculation formula is simplified to: δ = arctan(Lκ) In the formula, L is the total wheelbase, and κ is the current path curvature; Introduce the cubic term correction formula δ' = δ + kδ 3 In the formula, k is the slip suppression coefficient; thus, the rear-wheel steering angle δ' is obtained; The vehicle speeds of other driving wheels are dynamically allocated according to their distances to the steering center O: For the outer wheel, For the inner wheel, where d i is the lateral offset from the steering center O in the i-th round, κ is the curvature radius of the current path, v i is the wheel speed, v ref is the reference vehicle speed, and R is the theoretical turning radius.

6. The dual-mode steering cooperative control method of a five-axis heavy-load AGV as described in claim 1, characterized in that, In the step S4, the motor speed is obtained in real time by using the motor sensor and the IMU and fed back to the underlying controller. The underlying controller uses the PID control method to adjust the P and I parameters before mass production of the product, and adjusts the hub motor speed and the steering motor speed according to the hub motor speed difference and the rear wheel angle difference Δδ, so that the control quantity tracks the reference control quantity.

7. A dual-mode steering collaborative control system for a five-axis heavy-duty AGV, which is used to implement the dual-mode steering collaborative control method described in any one of claims 1-6, characterized in that, The dual-mode steering coordination control system includes: A state information detection module, which is used to obtain the state information of the five-axis heavy-load AGV, including the vehicle speed v, the path trajectory curvature k, and the obstacle distance d; A decision-making module, which is used to determine the scenario working condition according to the state information of the five-axis heavy-load AGV, make a decision on the steering mode of the five-axis heavy-load AGV according to the scenario working condition, and send a steering mode switching command to the underlying controller; An underlying controller, which is used to calculate the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode according to the received steering mode switching command and the state information of the five-axis heavy-load AGV, generate motion parameters as reference control quantities, and adjust the speeds of the steering motor and the hub motor to achieve coordinated control of the steering motion.

8. The dual-mode steering collaborative control system of a five-axis heavy-load AGV according to claim 7, characterized in that, The state information detection module includes: A hub motor encoder, which is used to obtain the vehicle speed of the five-axis heavy-load AGV in real time; A path planning module, which is used to output a planned path and obtain the path trajectory curvature; An obstacle perception module, which is used to detect the obstacle distance.

9. The dual-mode steering collaborative control system of a five-axis heavy-duty AGV according to claim 7, wherein The underlying controller includes a motion calculation module, which is used to calculate the linear velocity and angular velocity required for each wheel of the five-axis heavy-load AGV in the corresponding steering mode and generate motion parameters.

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