Dual-power composite steering control method and system for heavy-load AGV

Abstract

The invention belongs to the field of mobile robot control, and particularly relates to a dual-power composite steering control method and system for a heavy-load AGV, and the method comprises the following steps: 1), a vehicle-mounted controller receives a given path plan, a vehicle body controller obtains given speeds of driving motors on the left side and the right side, and the given speeds of driving motors on the left side and the right side are obtained; the differential steering control driving motor provides steering torque to drive the virtual rudder to steer; (2) the vehicle-mounted controller collects numerical values of multi-circle absolute value encoders installed on the front virtual rudder and the rear virtual rudder in real time, and deviation angles of the front virtual rudder and the rear virtual rudder in the vehicle length direction are obtained; the vehicle-mounted controller compares the deviation angle with a target steering planning angle to obtain an angle deviation value; (3) a load-turning radius-torque model is established, and the torque needed by steering of the virtual rudder is obtained according to the obtained angle deviation value, the planned turning radius and the current load; and 4) according to the torque required by the steering of the virtual rudder, the steering torque provided by the driving motor is combined to finally realize the steering control of the vehicle body.

Description

Technical Field

[0001] The invention belongs to the field of mobile robot control, in particular to a dual-power compound steering control method and system for a heavy-loaded AGV. Background Art

[0002] The steering control of outdoor heavy-duty AGVs used in port environments generally adopts the mature axle steering form, but the body is relatively high and cannot realize self-loading and unloading of goods. It requires additional cranes or other auxiliary equipment to cooperate with it. Some application scenarios require heavy-duty AGVs to be able to achieve oblique paths, which cannot be achieved by ordinary axle steering forms.

[0003] Traditional AGVs mostly use a single power source for steering control, such as relying solely on motors to drive wheel steering, or relying solely on hydraulic systems to drive steering mechanisms. However, under heavy load conditions, a single power source faces many limitations. On the one hand, if it is driven only by a motor, due to the sharp increase in friction caused by heavy loads and the large moment of inertia, the motor needs to output a huge amount of power to achieve precise steering. This not only places too high requirements on the performance specifications of the motor itself, increasing costs, but is also prone to failure due to motor overload, affecting the reliability and stability of the AGV. On the other hand, if it relies solely on a hydraulic system, although the hydraulic device can provide a large thrust, the hydraulic system has the problem of relatively slow response speed and difficult to fine-tune control accuracy. It is difficult to meet the precise real-time control requirements for steering angles and angular velocities under complex path planning, and it will also cause the AGV to deviate during the steering process and fail to complete the transportation task efficiently and accurately.

[0004] In addition, existing steering control methods lack effective load perception and dynamic adaptation mechanisms when faced with the frequent starting and stopping of heavy-loaded AGVs and complex and changeable driving paths. For example, when an AGV turns with cargo of different weights, the required steering torque will change significantly due to the effect of centrifugal force, and traditional methods cannot flexibly adjust the steering power according to load changes in time, further exacerbating the problems of inaccurate steering and difficult control. Furthermore, with the development of industrial intelligence, the requirements for AGV's autonomous navigation and path planning capabilities are increasing. Traditional steering control methods are difficult to seamlessly connect with advanced path planning algorithms, and cannot give full play to the advantages of AGV in complex operating environments, hindering the improvement of industrial production efficiency.

[0005] In summary, there is an urgent need for a new dual-power compound steering control method and system for heavy-load AGVs, which can integrate the advantages of multiple power sources, have load adaptive adjustment capabilities, and achieve efficient coordination with intelligent path planning to meet the precise, efficient and reliable transportation needs of modern industrial heavy-load logistics. Summary of the invention

[0006] The purpose of the present invention is to provide a dual-power compound steering control method and system for a heavy-duty AGV, which is based on a dual-power compound steering control method of a motor differential and a hydraulic proportional valve, and can realize steering control on a vehicle body with limited height, and can realize the oblique trajectory control of the vehicle.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a dual-power compound steering control method for a heavy-duty AGV, comprising the following steps:

[0008] 1) The vehicle controller receives the given path planning, the heavy-load AGV runs, and the vehicle body controller obtains the speed setting of the drive motors on the left and right sides, and controls the drive motors through differential steering to provide steering torque to drive the virtual rudder to steer;

[0009] 2) The on-board controller collects the values ​​of the multi-turn absolute encoders installed on the front and rear virtual rudders in real time, and obtains the deviation angle between the front and rear virtual rudders and the vehicle length direction; the on-board controller compares the deviation angle with the target steering planning angle to obtain the angle deviation value;

[0010] 3) Establish a load-turning radius-torque model, and obtain the torque required for virtual rudder steering based on the obtained angle deviation value, the planned turning radius and the current load;

[0011] 4) According to the torque required for virtual rudder steering, combined with the steering torque provided by the drive motor, the operating parameters of the wheels on both sides are controlled respectively, and finally the vehicle steering control is realized.

[0012] In step 1), the vehicle body controller obtains the given speeds of the drive motors on the left and right sides, specifically:

[0013] 1-1) Assume that the target steering angle θ given by the path planning target , desired steering angular velocity ω targe and the current vehicle speed v;

[0014] 1-2) According to the kinematic model of the vehicle, the target speed v of the left and right motors is calculated left and v right for:

[0015]

[0016] Wherein, L is the wheelbase of the vehicle;

[0017] 1-3) Set the target speed v of the left and right motors left and v right The signal is sent to the corresponding motor driver, which drives the motor to output the corresponding steering torque to drive the virtual rudder to steer.

[0018] In step 1), the following steps are also performed:

[0019] a. During the information update process of the planned path, recalculate the v of the left and right motors left and v right ;

[0020] b. Get the speed error Δv left and Δv right ,Right now:

[0021] Δv right =v right -v right_actual

[0022] Among them, v left_actual and v right_actual They are the actual speeds of the left and right motors collected respectively;

[0023] c. According to the speed error, use the PID control algorithm to calculate the control signal increment Δu required by the motor driver left and Δu right ,Right now:

[0024]

[0025] Among them, K p , K i , K d are proportional, integral, and differential coefficients respectively, and Δu is the control signal increment required by the motor driver, including Δu left and Δu right , Δv is the speed error, including Δv left and Δv right .

[0026] The step 2) is specifically:

[0027] 2-1) Assume that the value collected by the multi-turn absolute encoder on the front virtual rudder is E front The value collected by the multi-turn absolute encoder on the rear virtual rudder is E back ;

[0028] 2-2) Get the current actual angle value θ of the front and rear virtual rudders front and θ back They are:

[0029] θ front =E front ·Δθ

[0030] θ back =E back ·Δθ

[0031] Among them, Δθ is the angle value corresponding to each turn of the multi-turn absolute encoder;

[0032] 2-3) Assuming that the vehicle length direction is the positive direction of the x-axis and the angle is 0°, calculate the deviation angle α between the front and rear virtual rudders and the vehicle length direction front and α back They are:

[0033] α front =θ front -θ x

[0034] α back =θ back -θ x

[0035] Among them, θ x is the angle value corresponding to the vehicle length direction;

[0036] 2-4) Compare the calculated deviation angle with the target heading planning angle θ target Perform difference calculation to obtain the angle deviation value Δα front and Δα back .

[0037] The step 4) is specifically:

[0038] 3-1) Assume that the current load mass is m, the planned turning radius is r, and the vehicle's moment of inertia is I;

[0039] 3-2) Establish the following load-turning radius-torque model, namely:

[0040]

[0041] Among them, T is the torque required for virtual rudder steering, k1, k2, k3, k4 are coefficients determined according to vehicle characteristics and virtual rudder structure respectively;

[0042] 3-3) By substituting the currently known load, turning radius, and calculated deviation angle into the established load-turning radius-torque model, the torque T required for virtual rudder steering can be calculated.

[0043] The step 5) is specifically:

[0044] 4-1) According to the calculated virtual rudder steering torque T, control the opening direction of the virtual rudder hydraulic reversing valve and the opening size of the pressure reducing valve;

[0045] 4-2) The fitting function of the mapping relationship between torque, hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P is:

[0046] T=f(S,P)

[0047] 4-3) Obtain the corresponding hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P by inversely solving the fitting function;

[0048] 4-4) Send the control signal S to the corresponding virtual rudder to control the hydraulic reversing valve to open in the required direction, and at the same time adjust the pressure reducing valve to the corresponding pressure value P, so that the hydraulic system outputs appropriate power, which works together with the steering torque provided by the motor to finally achieve vehicle steering control.

[0049] The operating parameters of the wheels on both sides include: the required vehicle speed, the opening direction of the hydraulic reversing valve group and the opening size of the pressure reducing valve of the hydraulic reversing valve group.

[0050] A control system of a dual-power compound steering control system for a heavy-load AGV, which is arranged on the heavy-load AGV, comprises:

[0051] The drive motor group is installed at the bottom of the heavy-load AGV, which is used to drive the four wheels on the left and right sides of the heavy-load AGV respectively. The drive motors on the left and right sides use the differential steering control method to control the steering of the heavy-load AGV.

[0052] There are two virtual rudders, which are respectively set on the top of the heavy-load AGV corresponding to the front and rear wheels of the heavy-load AGV. The torque required for the rotation of the drive motors corresponding to the front and rear wheels is adjusted through its own pressure reducing control valve group;

[0053] The multi-turn absolute encoder is arranged on the steering shafts of the front and rear virtual rudders to measure the deviation angle of the corresponding virtual rudder relative to the vehicle's driving direction;

[0054] The vehicle body controller is used to collect the values ​​of the multi-turn absolute encoders installed on the front and rear virtual rudders in real time, calculate the deviation angle between the front and rear virtual rudders and the vehicle length direction, compare it with the target heading planning angle, and combine it with the planned turning radius to obtain the torque required for virtual rudder steering, control the operating parameters of the wheels on both sides respectively, and finally realize vehicle body steering control.

[0055] The control system of the dual-power compound steering control system of a heavy-load AGV is characterized by comprising a memory and a processor; the memory is used to store a computer program; the processor is used to implement the dual-power compound steering control method of a heavy-load AGV when executing the computer program.

[0056] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a dual-power compound steering control method for a heavy-load AGV as described in any one of claims 1 to 7.

[0057] The present invention has the following beneficial effects and advantages:

[0058] 1. The present invention uses the dual power of the motor and the hydraulic system to work together, and combines the path planning information to accurately calculate the given speed of the left and right motors, drive the virtual rudder to turn, and use the virtual rudder deviation angle fed back by the multi-turn absolute encoder in real time to accurately compare with the target heading, which can ensure that the AGV always turns accurately according to the predetermined path under various complex road conditions. Whether it is a right-angle turn in a narrow channel or a smooth passage through a large curvature curve, the steering error can be controlled within a very small range, greatly improving the navigation accuracy of the AGV, effectively avoiding collisions with obstacles or deviations from the transportation route, and improving transportation efficiency.

[0059] 2. The load-turning radius-torque model established by the present invention fully considers the impact of the current load on steering. When the AGV carries heavy objects, the model accurately calculates the torque required for virtual rudder steering based on the load data collected in real time, and reasonably allocates the power output of the motor and hydraulic system. This means that no matter how the weight of the goods carried by the AGV changes, the steering torque can be automatically adjusted to easily cope with the challenges of high friction and large rotational inertia brought by heavy loads, ensure stable and reliable steering performance, reduce the risk of damage to motors or hydraulic components due to overload, and extend the service life of the equipment.

[0060] 3. The controller of the present invention continuously updates the steering instructions according to the path planning, collects and analyzes multi-source data in real time, including motor speed feedback, encoder angle value, load information, etc., and dynamically adjusts the dual-power cooperation mode. This closed-loop control strategy enables the system to have self-optimization capabilities and can quickly adapt to the changing working environment. For example, when encountering temporary obstacles and requiring emergency avoidance, the system can instantly increase the steering power and adjust the steering angle to ensure that the AGV safely bypasses.

[0061] 4. In the case of height restrictions, heavy-duty AGVs cannot use a steering axle structure and require a crane or other auxiliary equipment. The control method of the present invention can realize automatic loading and unloading of heavy-duty AGVs at a relatively low height, making up for the disadvantage of insufficient power of a single steering method, and can also realize oblique path travel. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a schematic diagram of the composition of the heavy-duty AGV steering control mechanism of the present invention;

[0063] Figure 2 This is a schematic diagram of the heavy-duty AGV steering control method of the present invention;

[0064] Figure 3 This is a flowchart of the heavy-duty AGV steering control method of the present invention;

[0065] In the figure: 1 is a heavy-load AGV, 2 is a virtual rudder, 3 is a multi-turn absolute encoder, 4 is a hydraulic control valve group, and 5 is a motor drive wheel. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0067] like Figure 3 As shown, the flowchart of the heavy-duty AGV steering control method of the present invention is a dual-power compound steering control method of a heavy-duty AGV of the present invention, comprising the following steps:

[0068] 1) The onboard controller receives the given path planning, the heavy-load AGV1 runs, the vehicle body controller obtains the speed setting of the drive motors on the left and right sides, and controls the drive motors through differential steering to provide steering torque to drive the virtual rudder 2 to steer;

[0069] 2) The on-board controller collects the values ​​of the multi-turn absolute encoders 3 installed on the front and rear virtual rudders 2 in real time, and obtains the deviation angles between the front and rear virtual rudders 2 and the vehicle length direction; the on-board controller compares the deviation angle with the target steering planning angle to obtain the angle deviation value;

[0070] 3) Establishing a load-turning radius-torque model, and obtaining the torque required for the virtual rudder 2 to turn according to the obtained angle deviation value, the planned turning radius and the current load;

[0071] 4) According to the torque required for the virtual rudder 2 to turn, combined with the steering torque provided by the drive motor, the operating parameters of the motor drive wheel 5 are controlled respectively, and finally the vehicle body steering control is realized.

[0072] like Figure 2 As shown, it is a schematic diagram of the heavy-duty AGV steering control method of the present invention, and the specific detailed steps are as follows:

[0073] In step 1), the vehicle body controller obtains the speed reference of the drive motors on the left and right sides, specifically:

[0074] 1-1) Assume that the target steering angle θ given by the path planning target , desired steering angular velocity ω targe and the current vehicle speed v;

[0075] 1-2) According to the kinematic model of the vehicle, the target speed v of the left and right motors is calculated left and v right for:

[0076]

[0077] Wherein, L is the wheelbase of the vehicle;

[0078] 1-3) Set the target speed v of the left and right motors left and v rightThe signal is sent to the corresponding motor driver, which drives the motor to output the corresponding steering torque to drive the virtual rudder to steer.

[0079] Since the collected data is acquired in real time during the information update process of the planned path, the present embodiment uses the PID control algorithm to calculate the speed of the left and right drive motors in real time;

[0080] a. During the information update process of the planned path, recalculate the v of the left and right motors left and v right ;

[0081] b. Get the speed error Δv left and Δv right ,Right now:

[0082] Δv right =v right -v right_actual

[0083] Among them, v left_actual and v tight_actual They are the actual speeds of the left and right motors collected respectively;

[0084] c. According to the speed error, use the PID control algorithm to calculate the control signal increment Δu required by the motor driver left and Δu right ,Right now:

[0085]

[0086] Among them, K p , K i , K d are proportional, integral, and differential coefficients respectively, and Δu is the control signal increment required by the motor driver, including Δu left and Δu right , Δv is the speed error, including Δv left and Δv right .

[0087] Step 2), specifically:

[0088] 2-1) Assume that the value collected by the multi-turn absolute encoder on the front virtual rudder is E front The value collected by the multi-turn absolute encoder on the rear virtual rudder is E back ;

[0089] 2-2) Get the current actual angle value θ of the front and rear virtual rudders front and θ back They are:

[0090] θ front =Efront ·Δθ

[0091] θ back =E back ·Δθ

[0092] Among them, Δθ is the angle value corresponding to each turn of the multi-turn absolute encoder;

[0093] 2-3) Assuming that the vehicle length direction is the positive direction of the x-axis and the angle is 0°, calculate the deviation angle α between the front and rear virtual rudders and the vehicle length direction front and α back They are:

[0094] α front =θ front -θ x

[0095] α back =θ back -θ x

[0096] Among them, θ x is the angle value corresponding to the vehicle length direction;

[0097] 2-4) Compare the calculated deviation angle with the target heading planning angle θ target Perform difference calculation to obtain the angle deviation value Δα front and Δα back .

[0098] Step 3), specifically:

[0099] 3-1) Assume that the current load mass is m, the planned turning radius is r, and the vehicle's moment of inertia is I;

[0100] 3-2) Establish the following load-turning radius-torque model, namely:

[0101]

[0102] Among them, T is the torque required for virtual rudder steering, k1, k2, k3, k4 are coefficients determined according to vehicle characteristics and virtual rudder structure respectively;

[0103] 3-3) By substituting the currently known load, turning radius, and calculated deviation angle into the established load-turning radius-torque model, the torque T required for virtual rudder steering can be calculated.

[0104] Step 4), specifically:

[0105] 4-1) controlling the opening direction of the hydraulic reversing valve and the opening size of the pressure reducing valve of the virtual rudder (2) according to the calculated torque T required for the virtual rudder to turn;

[0106] 4-2) The fitting function of the mapping relationship between torque, hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P is:

[0107] T=f(S,P)

[0108] 4-3) Obtain the corresponding hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P by inversely solving the fitting function;

[0109] 4-4) Send the control signal S to the corresponding virtual rudder 2, control the hydraulic reversing valve to open in the required direction, and adjust the pressure reducing valve to the corresponding pressure value P, so that the hydraulic system outputs appropriate power, which works together with the steering torque provided by the motor to finally realize the vehicle steering control.

[0110] like Figure 1 As shown, it is a schematic diagram of the composition of the steering control mechanism of a heavy-duty AGV of the present invention. The control system of the dual-power compound steering control system of a heavy-duty AGV of the present invention is arranged on the heavy-duty AGV, and includes:

[0111] The drive motor group is installed at the bottom of the heavy-load AGV, which is used to drive the four wheels on the left and right sides of the heavy-load AGV respectively. The drive motors on the left and right sides use the differential steering control method to control the steering of the heavy-load AGV.

[0112] There are two virtual rudders 2, which are respectively arranged on the top of the heavy-load AGV (1) corresponding to the front wheel and the rear wheel of the heavy-load AGV 1, and adjust the torque required for the rotation of the driving motors corresponding to the front wheel and the rear wheel through their own pressure reducing control valve group 4;

[0113] The multi-turn absolute encoder 3 is arranged on the steering shafts of the front and rear virtual rudders 2, and is used to measure the deviation angle of the corresponding virtual rudder 2 relative to the driving direction of the vehicle;

[0114] The vehicle body controller is used to collect the values ​​of the multi-turn absolute encoders installed on the front and rear virtual rudders 2 in real time, calculate the deviation angles between the front and rear virtual rudders and the vehicle length direction, compare them with the target heading planning angle, and obtain the torque required for the virtual rudder 2 to turn in combination with the planned turning radius, and control the operating parameters of the motor drive wheel 5 respectively, so as to finally realize the vehicle body steering control.

[0115] Embodiment 1:

[0116] In the attached figure Figure 1 to Figure 2 What is shown is an application example of the present invention, which is used for loading and unloading materials on a certain type of heavy-duty AGV (1), and its prototype has completed functional performance test verification.

[0117] This example is applied to an outdoor heavy-load AGV, which is equipped with 4 sets of independent electric drive wheel groups 4, and two sets of front and rear virtual rudders 2 driven to rotate by hydraulic valve groups. Each virtual rudder is equipped with a multi-turn absolute encoder 3 to measure the deflection angle.

[0118] according to Figure 2 The schematic diagram of the heavy-duty AGV steering control method is as follows: according to the given path planning, the controller calculates the speed given of the motors on the left and right sides, and the motors provide a certain steering torque to drive the virtual rudder to steer; at the same time, the controller calculates the deviation angle between the front and rear virtual rudders and the vehicle length direction based on the multi-turn absolute encoder values ​​installed on the front and rear virtual rudders collected in real time, and compares it with the target heading planning angle. Combined with the planned turning radius and current load, a load-turning radius-torque model is established to calculate the torque required for virtual rudder steering, and control the opening direction of the hydraulic reversing valve and the opening size of the pressure reducing valve; the two forces work together to ultimately achieve vehicle steering control.

[0119] The prototype test shows that the present invention has fully utilized the flexible steering action and small body height, and can be equipped with a self-loading and unloading mechanism to realize automatic loading and unloading of goods. This not only reduces the cost, but also increases the loading and unloading efficiency by more than 3 times.

[0120] Those skilled in the art will appreciate that the above are only preferred embodiments of the present invention, and the various embodiments of the present disclosure and / or the features described in the claims may be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. It is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or perform equivalent substitutions on some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

[0121] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A dual-power compound steering control method for a heavy-duty AGV, characterized in that: The following steps are involved: 1) The vehicle controller receives the given path plan, the heavy-load AGV (1) runs, the vehicle body controller obtains the speed setting of the drive motors on the left and right sides, and controls the drive motors through differential steering to provide steering torque to drive the virtual rudder (2) to steer; 2) The on-board controller collects the values ​​of the multi-turn absolute encoders (3) installed on the front and rear virtual rudders (2) in real time, and obtains the deviation angles between the front and rear virtual rudders (2) and the vehicle length direction; The on-board controller compares the deviation angle with the target steering planning angle to obtain the angle deviation value; 3) establishing a load-turning radius-torque model, and obtaining the torque required for the virtual rudder (2) to turn according to the obtained angle deviation value, the planned turning radius and the current load; 4) Based on the torque required for steering of the virtual rudder (2), combined with the steering torque provided by the driving motor, the operating parameters of the motor driving wheels (5) are controlled respectively, and finally the steering control of the vehicle body is realized.

2. The dual-power compound steering control method for a heavy-load AGV according to claim 1, characterized in that: In step 1), the vehicle body controller obtains the given speed of the drive motors on the left and right sides, specifically: 1-1) Assume that the target steering angle θ given by the path planning target , desired steering angular velocity ω targe and the current vehicle speed v; 1-2) According to the kinematic model of the vehicle, the target speed v of the left and right motors is calculated left and v right for: Wherein, L is the wheelbase of the vehicle; 1-3) Set the target speed v of the left and right motors left and v right The signal is sent to the corresponding motor driver, which drives the motor to output the corresponding steering torque to drive the virtual rudder to steer.

3. A dual-power compound steering control method for a heavy-load AGV according to claim 1 or 2, characterized in that: In step 1), the following steps are also performed: a. During the information update process of the planned path, recalculate the v of the left and right motors left and v right ; b. Get the speed error Δv left and Δv right ,Right now: Δv left =v left -v leftactual ,Δv right =v right -v right_actual Among them, v left_actual and v right_actual They are the actual speeds of the left and right motors collected respectively; c. According to the speed error, use the PID control algorithm to calculate the control signal increment Δu required by the motor driver left and Δu right ,Right now: Among them, K p , K i , K d are proportional, integral, and differential coefficients respectively, and Δu is the control signal increment required by the motor driver, including Δu left and Δu right , Δv is the speed error, including Δv left and Δv right .

4. The dual-power compound steering control method for a heavy-load AGV according to claim 1 is characterized in that: The step 2) is specifically: 2-1) Assume that the value collected by the multi-turn absolute encoder on the front virtual rudder is E front The value collected by the multi-turn absolute encoder on the rear virtual rudder is E back ; 2-2) Get the current actual angle value θ of the front and rear virtual rudders front and θ back They are: i front =E front ·Dth i back =E back ·Dth Among them, Δθ is the angle value corresponding to each turn of the multi-turn absolute encoder; 2-3) Assuming that the vehicle length direction is the positive direction of the x-axis and the angle is 0°, calculate the deviation angle α between the front and rear virtual rudders and the vehicle length direction front and α back They are: a front =θ front -θ x a back =θ back -θ x Among them, θ x is the angle value corresponding to the vehicle length direction; 2-4) Compare the calculated deviation angle with the target heading planning angle θ target Perform difference calculation to obtain the angle deviation value Δα front and Δα back .

5. The dual-power compound steering control method for a heavy-load AGV according to claim 1, characterized in that: The step 4) is specifically: 3-1) Assume that the current load mass is m, the planned turning radius is r, and the vehicle's moment of inertia is I; 3-2) Establish the following load-turning radius-torque model, namely: Among them, T is the torque required for virtual rudder steering, k1, k2, k3, k4 are coefficients determined according to vehicle characteristics and virtual rudder structure respectively; 3-3) By substituting the currently known load, turning radius, and calculated deviation angle into the established load-turning radius-torque model, the torque T required for virtual rudder steering can be calculated.

6. The dual-power compound steering control method for a heavy-load AGV according to claim 1, characterized in that: The step 5) is specifically: 4-1) controlling the opening direction of the hydraulic reversing valve and the opening size of the pressure reducing valve of the virtual rudder (2) according to the calculated torque T required for the virtual rudder to turn; 4-2) The fitting function of the mapping relationship between torque, hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P is: T=f(S,P) 4-3) Obtain the corresponding hydraulic reversing valve control signal S and pressure reducing valve opening pressure value P by inversely solving the fitting function; 4-4) Send the control signal S to the corresponding virtual rudder (2), control the hydraulic reversing valve to open in the required direction, and adjust the pressure reducing valve to the corresponding pressure value P, so that the hydraulic system outputs appropriate power, which works together with the steering torque provided by the motor to finally achieve vehicle steering control.

7. The dual-power compound steering control system for a heavy-duty AGV according to claim 1, characterized in that: The operating parameters of the wheels on both sides include: the required vehicle speed, the opening direction of the hydraulic reversing valve group (4) and the opening size of the pressure reducing valve of the hydraulic reversing valve group (4).

8. The control system of the dual-power compound steering control system of a heavy-load AGV according to claim 1, which is arranged on the heavy-load AGV, is characterized in that: include: The drive motor group is installed at the bottom of the heavy-load AGV, which is used to drive the four wheels on the left and right sides of the heavy-load AGV respectively. The drive motors on the left and right sides use the differential steering control method to control the steering of the heavy-load AGV. There are two virtual rudders (2), which are respectively arranged on the top of the heavy-load AGV (1) corresponding to the front wheels and the rear wheels of the heavy-load AGV (1), and adjust the torque required for the rotation of the driving motors corresponding to the front wheels and the rear wheels through their own pressure reducing control valve groups (4); A multi-turn absolute value encoder (3) is arranged on the steering shafts of the front and rear virtual rudders (2) and is used to measure the deviation angle of the corresponding virtual rudder (2) relative to the driving direction of the vehicle; The vehicle body controller is used to collect the values ​​of the multi-turn absolute encoders installed on the front and rear virtual rudders (2) in real time, calculate the deviation angles of the front and rear virtual rudders from the vehicle length direction, compare them with the target heading planning angle, and obtain the torque required for the virtual rudder (2) to turn in combination with the planned turning radius, and respectively control the operating parameters of the motor drive wheel (5), thereby finally realizing the steering control of the vehicle body.

9. The control system of the dual-power compound steering control system for a heavy-duty AGV according to claim 1, characterized in that: It comprises a memory and a processor; the memory is used to store a computer program; the processor is used to implement a dual-power compound steering control method for a heavy-load AGV as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the dual-power compound steering control method for a heavy-load AGV as described in any one of claims 1 to 7 is implemented.

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