AGV double-vehicle linkage adaptive motion control method and system

Abstract

The invention discloses an AGV double-vehicle linkage adaptive motion control method and system, and belongs to the technical field of industrial automatic logistics equipment. According to the method, double vehicles are integrated into a unified rigid whole by constructing an eight-steering-wheel virtual rigid body motion model; realizing communication delay compensation by adopting a dynamic cutting and interpolation algorithm based on a time queue; and rapidly converging the collaborative error by using a sliding-mode control algorithm fusing a space error and an error change rate quadratic term. According to the method, the technical problems of poor track consistency and large synchronization error caused by model splitting, communication delay and external disturbance in heavy-load AGV cooperative motion are effectively solved, and the cooperative motion precision and the anti-interference capability of heavy-load logistics equipment are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial logistics intelligentization, in particular to an AGV double-vehicle linkage adaptive motion control method and system. BACKGROUND

[0002] The automatic guided vehicle (AGV) is the core equipment in the modern industrial automated logistics system, and is widely used in material handling, assembly line distribution and flexible manufacturing system. In the assembly scene of heavy equipment (such as buses and aircraft parts), due to the characteristics of super large and super heavy materials, the carrying capacity and size of a single AGV cannot meet the demand, prompting the multi-AGV collaborative operation technology to become the key to solving the problem.

[0003] Currently, the master-slave tracking control is the mainstream scheme of double-AGV linkage. In this scheme, the master vehicle moves independently according to the preset trajectory, and sends its own pose and speed information to the slave vehicle through wireless communication, and the slave vehicle performs tracking control according to the received information. However, the prior art has significant defects: first, it regards the master and slave vehicles as two independent motion units, lacks a unified cooperative kinematics model, resulting in poor trajectory consistency of the double vehicles when turning and changing tracks, and easy occurrence of motion interference and tail shaking phenomenon; second, the system communication delay is not effectively compensated, causing the slave vehicle control command to lag, introducing synchronization error; third, the traditional control algorithm (such as PID) has poor robustness when dealing with ground disturbances and load changes, insufficient dynamic adjustment capability, and slow error convergence; finally, the existing system lacks the ability to dynamically adjust the distance between the double vehicles, making it difficult to flexibly adapt to the carrying needs of different specifications of materials, and has low flexibility.

[0004] Therefore, the prior art cannot meet the stringent requirements of AGV double-vehicle cooperative motion control in heavy load and high precision applications, and there is an urgent need for a new control method that can integrate double-vehicle models, compensate for communication delays, have strong anti-interference ability, and support dynamic adjustment of distance. SUMMARY

[0005] The technical problem to be solved by the present application is the poor trajectory consistency, large synchronization error and weak anti-interference ability caused by model fragmentation, communication delay and external disturbance in the existing heavy load AGV double-vehicle linkage system.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: an AGV double-vehicle linkage adaptive motion control method, comprising the following steps: An eight-steering-wheel virtual rigid body motion model is constructed, and the eight steering wheels of the master vehicle and the slave vehicle are uniformly mapped to a rigid whole model with the midpoint of the double-vehicle connection as the center; The master vehicle generates the overall motion command of the virtual rigid body model according to the preset motion trajectory, and calculates the target motion state of each steering wheel based on the model; The master vehicle sends the whole motion instruction with timestamp to the slave vehicle; The slave vehicle receives the whole motion instruction with timestamp and dynamically trims and interpolates the instruction based on the calculated communication delay to generate a target speed instruction synchronized with the master vehicle motion state; The slave vehicle independently calculates the steering control amount of the rudder according to the synchronized target speed instruction and the whole pose deviation; Based on the actual distance error between the two vehicles and its rate of change, a quadratic dynamic sliding mode control algorithm is used to generate the slave vehicle speed compensation amount; The compensated final speed instruction and steering control amount are sent to the slave vehicle rudder actuator to drive the slave vehicle to move, so as to realize the coordinated linkage with the master vehicle.

[0007] Further, the step of the master vehicle sending the whole motion instruction with timestamp to the slave vehicle comprises: The master vehicle controller generates and stores a target speed array queue for a future period of time at a fixed period, and each array element has an accurate timestamp; The target speed array queue is sent to the slave vehicle through wireless communication.

[0008] Further, the step of the slave vehicle receiving the whole motion instruction with timestamp and dynamically trimming and interpolating the instruction based on the calculated communication delay to generate a target speed instruction synchronized with the master vehicle motion state comprises: The slave vehicle calculates the total communication delay time according to the time of receiving data; The received speed array queue is dynamically trimmed according to the total communication delay time to delete outdated instruction elements; The first element of the trimmed queue is linearly interpolated to calculate the synchronized target speed instruction accurately matched with the current time.

[0009] Further, the step of the slave vehicle independently calculating the steering control amount of the rudder according to the synchronized target speed instruction and the whole pose deviation comprises: The steering control amount is calculated by mapping based on the deviation function of the whole pose of the virtual rigid body model and the actual pose of the slave vehicle; the steering control amount includes the steering angle of each rudder of the slave vehicle, and the calculation of the steering angle makes the slave vehicle steering consistent with the master vehicle motion trajectory.

[0010] Further, the step of generating the slave vehicle speed compensation amount based on the actual distance error between the two vehicles and its rate of change using a quadratic dynamic sliding mode control algorithm comprises: A sliding mode surface is constructed by combining the quadratic terms of the distance error and the error rate of change; The slave vehicle speed compensation amount is dynamically calculated and output according to the sliding mode surface and its trend.

[0011] Further, in the step of constructing the sliding mode surface of the fusion of the distance error and the error change rate quadratic term, the function expression of the sliding mode surface contains the error change rate, the first order term and the quadratic term of the error; the coefficients of the first order term and the quadratic term are determined through system stability analysis to ensure that the sliding mode surface has dynamic convergence characteristics.

[0012] Further, the AGV double-vehicle linkage adaptive motion control method further includes a double-vehicle distance dynamic adjustment step, specifically: determine the double-vehicle target distance according to the length of the target material to be carried; adjust the current distance to the target distance step by step with a preset maximum step length to avoid motion impact.

[0013] Further, the AGV double-vehicle linkage adaptive motion control method further includes a pose feedback optimization step, specifically: estimate the real pose of the master vehicle in real time by fusing the odometer data and the visual sensor data of the master vehicle; feed back the estimated real pose of the master vehicle to the trajectory tracking closed loop for optimizing the overall motion instruction.

[0014] Further, the AGV double-vehicle linkage adaptive motion control method further includes a safety monitoring step, specifically: real-time interaction of the safety interlocking signal between the master vehicle and the slave vehicle; trigger the corresponding control mode switching including deceleration, stop or emergency stop according to the received safety signal level.

[0015] The application also provides an AGV double-vehicle linkage adaptive motion control system, comprising: a virtual rigid body modeling module for constructing an eight-steering-wheel virtual rigid body motion model, which uniformly maps the eight steering wheels of the master vehicle and the slave vehicle to a rigid whole model with the midpoint of the double-vehicle connection as the center; a master vehicle control module for the master vehicle to generate the overall motion instruction of the virtual rigid body model according to the preset motion trajectory, and to calculate the target motion state of each steering wheel based on the model; a wireless communication module for the master vehicle to send the overall motion instruction with a time stamp to the slave vehicle; a delay compensation module for the slave vehicle to receive the overall motion instruction with a time stamp, and to generate a target speed instruction synchronized with the motion state of the master vehicle by dynamically clipping and interpolating the instruction based on the calculated communication delay; a steering calculation module for the slave vehicle to independently calculate the steering control amount of its steering wheel according to the synchronized target speed instruction and the overall pose deviation; A sliding mode compensation control module is configured to generate a slave vehicle speed compensation amount based on a double-vehicle actual distance error and a rate of change thereof using a second-order dynamic sliding mode control algorithm; A steering wheel execution module is configured to send a final speed instruction after compensation and a steering control amount to each steering wheel execution mechanism of the slave vehicle to drive the slave vehicle to move to realize cooperative linkage with the master vehicle.

[0016] The application has the beneficial effects that: the application integrates the master-slave double vehicles into a unified rigid whole for cooperative control by constructing an eight-steering-wheel virtual rigid body motion model, thus fundamentally solving the trajectory consistency problem caused by the traditional split model; the communication delay is effectively compensated by a dynamic clipping and interpolation algorithm based on a time queue, thus realizing accurate synchronization of the master-slave vehicle speed instructions in the time dimension; the distance error and external disturbance are quickly suppressed by a second-order dynamic sliding mode compensation algorithm; and the synchronization, stability and anti-interference ability of the system in a complex industrial environment are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A flow chart of an AGV double-vehicle linkage adaptive motion control method of an embodiment of the application; Figure 2 A schematic diagram of an eight-steering-wheel virtual rigid body motion model of an embodiment of the application; Figure 3 A double-vehicle communication schematic diagram of an embodiment of the application; Figure 4 A block diagram of an AGV double-vehicle linkage adaptive motion control device of an embodiment of the application. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0019] It should be noted that the description of "first", "second" and the like in the application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the application.

[0020] Please refer toFigure 1 The first embodiment of the present application is an AGV double-vehicle linkage adaptive motion control method, comprising the following steps: S10, a virtual rigid body motion model of eight steering wheels is constructed, and the eight steering wheels of the master vehicle and the slave vehicle are uniformly mapped to a rigid whole model with the midpoint of the double-vehicle connection as the center; In this embodiment, as shown in the figure, a mechanical model of single-vehicle four steering wheels is accurately established, and the accurate position coordinates of the rotation center of each steering wheel in the two-dimensional plane are determined with the motion center point of the trolley itself as the origin. At the same time, the length and width extension size parameters of the trolley are determined, which provide accurate basic data for the subsequent establishment of the whole model. Figure 2 A two-dimensional rectangular coordinate system is established with the motion center point of the trolley itself as the origin O', and the position parameters of the steering wheels are as follows: the rotation center coordinates of the four steering wheels (numbered 1-4) are:

[0021] Steering wheel 1: (x1, y1) = (+1.072m, -0.385m); Steering wheel 2: (x2, y2) = (-1.072m, +0.385m); Steering wheel 3: (x3, y3) = (+1.136m, +0.453m); Steering wheel 4: (x4, y4) = (-1.136m, -0.453m); Vehicle body size: length 3m, width 2m.

[0022] On the basis of the mechanical model of single-vehicle four steering wheels, a virtual rigid body motion model of eight steering wheels is constructed in combination with the actual distance between the front and rear vehicles. The master and slave double vehicles are regarded as a rigid whole with the connection midpoint O as the center, and the possible error states of the rigid body model in the motion process are accurately defined according to the relevant kinematics and dynamics principles, thereby providing accurate error analysis basis for the subsequent control strategy; O is the virtual rigid body center, the coordinate origin (0, 0, 0), and is the kinematic reference center of the whole virtual rigid body model; O1 is the motion center point of the master vehicle (front vehicle) itself ( ), located on the right side of the X axis, and the distance from O is L / 2 (L is the center point distance between the master and slave vehicles); O2 is the motion center point of the slave vehicle (rear vehicle) itself ( ), located on the left side of the X axis, and the distance from O is L / 2, and O1 is symmetrical about O; θ is the overall heading angle of the virtual rigid body (the angle with the X axis of the two-dimensional coordinate system), that is, the unified heading angle when the master and slave vehicles move cooperatively; L is the center point distance between the master and slave vehicles (the initial value is 4m, and the dynamic adjustment range is 4-6m). ​

[0023] (x' 1i ,y' 1i ) is the coordinate of the i-th steering wheel of the host vehicle (i = 1, 2, 3, 4) relative to its own center point O1; (x 1i = x' 1i + L / 2 ,y 1i = y' 1i ) is the coordinate of the i-th steering wheel of the host vehicle (i = 1, 2, 3, 4) relative to the origin O; (x' 2j ,y' 2j ) is the coordinate of the j-th steering wheel of the slave vehicle (j = 1, 2, 3, 4) relative to its own center point O2; (x 2j = x' 2j - L / 2 ,y 1i = y' 2j ) is the coordinate of the j-th steering wheel of the slave vehicle (j = 1, 2, 3, 4) relative to the origin O; Mathematical solution formula of kinematic instruction and 8 steering wheel position angles: The kinematic instruction of the virtual rigid body is the overall motion parameter: linear velocity (v x ,v y ) (along the X and Y axes), and angular velocity ω (rotation around the O point). According to the principle of rigid body kinematics, the linear velocity and steering angle of each steering wheel need to meet the overall motion state.

[0024] S20, the host vehicle generates the overall motion instruction of the virtual rigid body model according to the preset motion trajectory, and solves the target motion state of each steering wheel based on the model; In this embodiment, the steering wheel linear velocity solution: any steering wheel The coordinate relative to O is (x k ,y k ), and the vector expression of its linear velocity is: ; Derivation explanation: the velocity of any point on a rigid body = the translational velocity of the rigid body + the linear velocity generated by the rotation of the rigid body (the cross product of the angular velocity and the position vector of the point to the rotation center) The steering wheel linear velocity is: ; Steering wheel steering angle solution: the steering angle α k of the steering wheel (included angle with the X axis) needs to be consistent with the direction of its linear velocity, that is: ; Error state definition (based on virtual rigid body center O): Define the error state of the coordinated motion of the two vehicles based on O, provide the basis for subsequent compensation control: ΔP t Synchronization error of virtual rigid body model: ΔP t =ΔP1-ΔP2; ΔP1 is the deviation of the master vehicle from the ideal position of the virtual rigid body model, ΔP1= O1- O1’, O1 is the actual position of the master vehicle, O1’ is the ideal position of the master vehicle; ΔP2 is the deviation of the slave vehicle from the ideal position of the virtual rigid body model. ΔP2= O2- O2’, O2 is the actual position of the slave vehicle, O2’ is the ideal position of the slave vehicle.

[0025] S30, the master vehicle sends the whole motion instruction with timestamp to the slave vehicle; Further, the step of the master vehicle sending the whole motion instruction with timestamp to the slave vehicle includes: The master vehicle controller generates and stores a target speed array queue for a future period of time at a fixed period, each array element is provided with an accurate timestamp; The target speed array queue is sent to the slave vehicle through wireless communication.

[0026] In this embodiment, the eight steering wheel model is specifically applied to the master-slave dual vehicle system. The front vehicle is the master vehicle and the rear vehicle is the slave vehicle. In the master vehicle motion model, the four steering wheels of the master vehicle are regarded as the first four physical wheels, and real-time walking and steering data are fed back. At the same time, the four steering wheels of the slave vehicle are regarded as the last four virtual wheels and are included in the model to feed back the corresponding walking and steering data. The motion control of the master vehicle is completely completed by itself, and the motion state is autonomously decided according to the preset trajectory planning and environmental perception information.

[0027] In the rear vehicle motion model, the four steering wheels of the rear vehicle itself are regarded as the last four physical wheels to feed back the walking and steering data, and the four steering wheels of the front vehicle are regarded as the first four virtual wheels to provide reference data for the rear vehicle model. The wheel speed of the rear vehicle is uniformly controlled by the master vehicle to ensure the speed coordination with the master vehicle; while the steering of the rear vehicle is independently calculated and controlled based on the overall pose information, so as to ensure that the rear vehicle can accurately follow the motion trajectory of the master vehicle and realize the coordinated motion of the two vehicles.

[0028] Physical wheel (master vehicle 4 steering wheel) feedback data: speed v 1i , steering angle ; Virtual wheel (slave vehicle 4 steering wheel) reference data: speed v 2i , steering angle .

[0029] Master vehicle independent control speed instruction: V m =[vx ,v y ,ω](v x Longitudinal velocity, v y Lateral velocity, ω (angular velocity).

[0030] Physical wheel (from the car's 4th steering wheel) feedback data: speed v 2i Steering angle ; Virtual wheel (main vehicle 4 steering wheels) reference data: speed v 1i Steering angle .

[0031] Calculated from the vehicle's steering angle (based on the overall pose): (f is a steering angle mapping function based on virtual rigid body pose deviation to ensure trajectory following).

[0032] like Figure 3 As shown, pairing and communication are achieved through Bluetooth communication devices installed on both the master and slave vehicles. During communication, the transmitted data follows clear classification and format specifications. Communication data sent from the master vehicle to the slave vehicle includes, but is not limited to, steering wheel speed commands, precise master vehicle position and orientation information, master vehicle safety interlock signals, real-time master vehicle steering wheel feedback data, precise communication timestamps, and the master vehicle's current control mode. Communication data sent from the slave vehicle to the master vehicle includes slave vehicle position and orientation information, slave vehicle safety interlock signals, slave vehicle steering wheel feedback data, communication timestamps, and the slave vehicle's control mode. Accurate exchange of this data provides crucial information support for the coordinated control of the two vehicles.

[0033] The main vehicle transmits data: timestamp (t); speed array V m =[v x ,v y [,ω]; Pose (x1,y1,θ1); Safety interlock signals (slow,stop,estop); Steering wheel feedback [v 1i ,α 1i ]; Control mode.

[0034] Data transmitted from the vehicle: pose Safety interlock signal (same as above); steering wheel feedback [v] 2j ,α 2j ]; Control mode feedback (mode).

[0035] S40. Receive the timestamped overall motion command from the vehicle, and dynamically trim and interpolate the command based on the calculated communication delay to generate a target speed command synchronized with the motion state of the main vehicle. Furthermore, the step of receiving the timestamped overall motion command from the vehicle and dynamically pruning and interpolating the command based on the calculated communication delay to generate a target speed command synchronized with the motion state of the master vehicle includes: The vehicle calculates the total communication delay time based on the time it receives the data. The received speed array queue is dynamically pruned based on the total communication delay time, and outdated instruction elements are deleted. Linear interpolation is performed on the first element of the pruned queue to calculate the target speed command that precisely matches the current time.

[0036] In this embodiment, based on the slave vehicle target speed synchronization and communication delay compensation using a time queue, the master vehicle controller calculates the delay τ relative to the current time t. fixd The target velocity V within a given time period pre The release interval is T, arranged in chronological order according to time t. pub Target speed array queue V pre (t) i ) = [v x , v y , ω], where v x and v y Let ω and t represent the velocity components in the two-dimensional plane, respectively, where ω represents the angular velocity and t represents the timestamp. The number of elements in the target velocity array of the main vehicle is N = τ. fixd / T pub The first element V pre (t0) represents the target speed published in the current control cycle. After the speed is published, the next element will be shifted forward by V. pre (t) i )= V pre (t) i+1 ).

[0037] Simultaneously, the main vehicle sends a target speed array V with precise timestamps. pre (t) i The data is given to the slave vehicle, which, upon receiving the speed array, determines the speed based on the current time t. now Calculate the total communication delay τ com (τ) com =τ proc +τ fluc Total communication delay includes fixed data processing delay τ proc (Measurable), dynamic communication fluctuation delay τ fluc (From the time the slave requests data to the time it receives the returned data), the target speed V will be... pre (t) i ) before [τ com / T pubOne element is deleted, and the remaining elements are moved forward and the compensation speed is calculated by linear interpolation: (t i ≤t sync ≤t i+1 ); V comp is the compensation speed, V i is the speed at the i-th moment, V i+1 is the speed at i+1 moment, t i is the time at the i-th moment, t i+1 is the time at i+1 moment, t sync is the synchronization time.

[0038] The result V comp is synchronized to the slave vehicle target speed release array queue V pre (t j ), the speed is updated by rolling interpolation, the synchronization error caused by the communication delay between the master and slave vehicles is accurately compensated, and the slave vehicle can respond to the speed command of the master vehicle in time and accurately, improving the synchronization and accuracy of the double vehicle motion.

[0039] S50, the slave vehicle independently calculates the steering control amount of the rudder according to the synchronized target speed command and the overall pose deviation; Further, the step of calculating the steering control amount of the rudder of the slave vehicle according to the synchronized target speed command and the overall pose deviation comprises: mapping calculation based on the deviation function of the overall pose of the virtual rigid body model and the actual pose of the slave vehicle to obtain the steering control amount; the steering control amount includes the steering angle of each rudder of the slave vehicle, and the calculation of the steering angle makes the slave vehicle steering consistent with the motion trajectory of the master vehicle.

[0040] In this embodiment, the master vehicle real pose estimation and state backtracking closed loop construction are performed: the master vehicle real pose is accurately estimated by comprehensively utilizing the master vehicle pose information, mileage feedback data and detection results of the depth camera, and using an advanced multi-sensor fusion algorithm. Through weighted fusion and error correction of different sensor data, the accuracy and reliability of the master vehicle pose estimation are improved. On this basis, a state backtracking closed loop system is constructed, the estimated master vehicle real pose information is fed back to the control strategy, the real-time adjustment and optimization of the master vehicle motion state are realized, and the master vehicle can accurately move according to the preset trajectory.

[0041] Trajectory tracking error (P pre is the predicted trajectory pose); Adjust the speed of the slave vehicle through feedback control: (Kp is the proportional coefficient to ensure error convergence).

[0042] S60, generating a slave vehicle speed compensation amount based on the actual distance error between the two vehicles and its rate of change using a quadratic dynamic sliding mode control algorithm; Further, the step of generating a slave vehicle speed compensation amount based on the actual distance error between the two vehicles and its rate of change using a quadratic dynamic sliding mode control algorithm comprises: constructing a sliding mode surface that incorporates the quadratic terms of the distance error and the rate of change of the error; dynamically calculating and outputting the slave vehicle speed compensation amount according to the sliding mode surface and its trend.

[0043] Further, in the step of constructing a sliding mode surface that incorporates the quadratic terms of the distance error and the rate of change of the error, the function expression of the sliding mode surface contains the rate of change of the error, the first-order term and the quadratic term of the error; the coefficients of the first-order term and the quadratic term are determined through system stability analysis to ensure that the sliding mode surface has a dynamic convergence characteristic.

[0044] S70, issuing the compensated final speed command and steering control amount to the slave vehicle steering wheel actuators to drive the slave vehicle to move, thereby achieving coordinated linkage with the host vehicle.

[0045] In this embodiment, the distance L between the host vehicle and the slave vehicle is estimated based on the true pose of the host vehicle act and compared with the ideal distance L set set by the eight-steering-wheel virtual rigid body motion model, and the error e (distance error, e = L act -L set ) between them is calculated. A quadratic dynamic sliding mode compensation algorithm is used to adjust the control parameters in real time according to the size and trend of the error, and generate the final wheel speed array. Applying this wheel speed array to the physical wheel actuators of the slave vehicle, through precise speed control and steering adjustment, the slave vehicle can quickly and accurately eliminate the error with the host vehicle, ensuring the synchronization accuracy and coordination performance of the two vehicles.

[0046] e' is the rate of change of the error, reflecting the trend of the error over time, and e' = 0 in the ideal state; s is a quadratic dynamic sliding mode surface that incorporates the quadratic terms of the error and the rate of change of the error, and is defined as: s = e' + λ1e + λ2e 2 ; where λ1>0, λ2>0 are sliding mode surface parameters (determined through system stability analysis, such as λ1=5, λ2=2) to ensure that the sliding mode surface has a dynamic convergence characteristic; u0 is the basic control amount, based on the converted slave vehicle speed command (containing v comp , v x0 , ω0) calculated from the compensation speed V y0 . u is the final control amount of the vehicle, u = u0 + Au, wherein Au is a sliding mode compensation amount; k is a sliding mode gain, which is set according to the upper limit of the maximum disturbance of the system.

[0047] Further, in a specific embodiment, the AGV double-vehicle linkage adaptive motion control method further includes a double-vehicle spacing dynamic adjustment step, specifically: determine the double-vehicle target spacing according to the length of the target material to be carried; adjust the current spacing to the target spacing step by step with a preset maximum step size to avoid motion impact.

[0048] In this embodiment, when the double vehicles need to adapt to different lengths of the material to be carried, the spacing parameters between the front four steering wheels and the rear four steering wheels in the virtual rigid body motion model of the eight steering wheels are adjusted by stages to realize dynamic adjustment of the double-vehicle spacing. The adjustment process follows certain control strategies and algorithms to ensure the smoothness and accuracy of the adjustment process and avoid problems such as system instability or material damage caused by too fast or too large spacing adjustment. Through this dynamic adjustment mechanism, the double-vehicle system can flexibly adapt to the carrying needs of different specifications of materials, improving the versatility and applicability of the system.

[0049] Target spacing L target (initial spacing L init , maximum single adjustment step size .

[0050] Adjustment times and step size: total adjustment amount adjustment times: is a ceiling function to ensure smooth adjustment at each step and avoid impact.

[0051] Further, in a specific embodiment, the AGV double-vehicle linkage adaptive motion control method further includes a pose feedback optimization step, specifically: estimate the real pose of the master vehicle in real time by fusing the odometer data of the master vehicle and the visual sensor data; real-time interaction between the master and slave vehicles for safety interlocking signals; trigger the corresponding control mode switching including deceleration, stop or emergency stop according to the received safety signal level.

[0052] ​In summary, the laser-guided AGV double-car linkage adaptive motion control scheme proposed in the present application realizes a breakthrough in the field of heavy-load AGV cooperative motion control through three core technical innovations, and achieves remarkable technical effects. First, by constructing an eight-steering-wheel virtual rigid body motion model, the kinematic parameters of the eight steering wheels of the master and slave cars are integrated into a rigid whole model with the connecting midpoint as the center, fundamentally solving the problem of poor trajectory consistency caused by the fragmentation of traditional double-car models, and laying a model foundation for high-precision cooperative control. Second, the innovative synchronization and communication delay compensation algorithm based on time queue realizes accurate quantitative compensation of communication delay through dynamic clipping and linear interpolation optimization, ensuring high matching of the slave car speed command and the master car motion state in the time dimension, and effectively eliminating synchronization errors caused by communication lag. Finally, for double-car cooperative errors and external disturbances, a quadratic dynamic sliding mode compensation algorithm is adopted, which realizes the rapid convergence and suppression of cooperative errors by constructing a sliding mode surface that integrates the quadratic terms of the distance error and the error rate, greatly improving the anti-interference ability and robustness of the system. Ultimately, this technical scheme is successfully applied in the 15-ton, 10-12.9-meter electric bus assembly transfer scene, achieving high-precision control indicators such as double-car synchronization position error ≤±15mm and angle error ≤0.5°, effectively solving the industry pain points of low cooperative precision and insufficient flexibility of traditional heavy-load AGVs, promoting the upgrading of heavy-load logistics equipment towards high precision and intelligence, and having important engineering application value and promotion prospects.

[0053] As shown in Figure 4 The present application also provides an AGV double-car linkage adaptive motion control system, which comprises: A virtual rigid body modeling module 10 is used to construct an eight-steering-wheel virtual rigid body motion model, and map the eight steering wheels of the master and slave cars into a rigid whole model with the connecting midpoint of the double car as the center; A master car control module 20 is used to generate the overall motion command of the virtual rigid body model according to the preset motion trajectory, and calculate the target motion state of each steering wheel based on the model; A wireless communication module 30 is used to send the overall motion command with timestamp from the master car to the slave car; A delay compensation module 40 is used to receive the overall motion command with timestamp by the slave car, and perform dynamic clipping and interpolation compensation on the command based on the calculated communication delay to generate a target speed command synchronized with the motion state of the master car; A steering calculation module 50 is used to independently calculate the steering control amount of the steering wheel of the slave car according to the synchronized target speed command and the overall pose deviation; A sliding mode compensation control module 60 is used to generate a speed compensation amount for the slave car based on the actual distance error and its rate of change between the double cars by using a quadratic dynamic sliding mode control algorithm; The steering wheel execution module 70 is configured to send the compensated final speed instruction and the steering control quantity to each steering wheel execution mechanism of the slave vehicle to drive the movement of the slave vehicle, so as to realize the cooperative linkage with the master vehicle.

[0054] Further, the wireless communication module 30 is specifically configured to: The master vehicle controller generates and stores a target speed array queue in a future period of time at a fixed period, and each array element is provided with an accurate time stamp; Further, the delay compensation module 40 is specifically configured to: The slave vehicle calculates the total communication delay time according to the time of receiving data; The received speed array queue is dynamically cropped according to the total communication delay time, and the outdated instruction elements are deleted; The first element of the cropped queue is linearly interpolated to calculate the synchronized target speed instruction accurately matched with the current time.

[0055] Further, the steering calculation module 50 is specifically configured to: The steering control quantity is calculated based on the deviation function of the overall pose of the virtual rigid body model and the actual pose of the slave vehicle, and the steering control quantity includes the steering angles of each steering wheel of the slave vehicle, and the calculation of the steering angles makes the steering of the slave vehicle consistent with the movement trajectory of the master vehicle.

[0056] Further, the sliding mode compensation control module 60 is specifically configured to: A sliding mode surface is constructed by fusing the quadratic term of the distance error and the error rate; The speed compensation quantity of the slave vehicle is dynamically calculated and output according to the sliding mode surface and its trend.

[0057] Further, in the step of constructing the sliding mode surface by fusing the quadratic term of the distance error and the error rate, the function expression of the sliding mode surface contains the error rate, the linear term and the quadratic term of the error; the coefficients of the linear term and the quadratic term are determined through system stability analysis to ensure that the sliding mode surface has a dynamic convergence characteristic.

[0058] Further, the AGV double-vehicle linkage adaptive motion control system further comprises a double-vehicle distance dynamic adjustment module, which is specifically configured to: The target distance between the double vehicles is determined according to the length of the target material to be carried; The current distance is gradually adjusted to the target distance at a preset maximum step length to avoid movement impact.

[0059] Further, the AGV double-vehicle linkage adaptive motion control system further comprises a pose feedback optimization module, which is specifically configured to: The real pose of the master vehicle is estimated in real time by fusing the odometer data and the visual sensor data of the master vehicle. The estimated real pose of the master vehicle is fed back to the trajectory tracking closed loop for optimizing the overall motion instruction.

[0060] Further, the AGV double-vehicle linkage adaptive motion control system further comprises a safety monitoring module, specifically configured to: real-time interaction of safety interlocking signals between the master and slave vehicles; According to the received safety signal level, trigger the corresponding control mode switching including deceleration, stop or emergency stop.

[0061] It should be noted that the skilled in the art can clearly understand the specific implementation process of the AGV double-vehicle linkage adaptive motion control system described above, which can refer to the corresponding description in the foregoing method embodiments. For the convenience and brevity of description, it will not be repeated here.

[0062] The above is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An AGV double vehicle linkage adaptive motion control method, characterized in that, The method comprises the following steps: A virtual rigid body motion model of eight steering wheels is constructed, and the eight steering wheels of the master vehicle and the slave vehicle are uniformly mapped to a rigid overall model with the midpoint of the double-vehicle connection as the center; The master vehicle generates overall motion instructions of the virtual rigid body model according to a preset motion trajectory, and calculates target motion states of each steering wheel based on the model; The master vehicle sends the overall motion instructions with time stamps to the slave vehicle; The slave vehicle receives the overall motion instructions with time stamps, dynamically trims and interpolates compensates the instructions based on a calculated communication delay, and generates target speed instructions synchronized with the motion state of the master vehicle; The slave vehicle independently calculates steering control amounts of the steering wheels according to the synchronized target speed instructions and overall pose deviations; Based on the actual distance error between the double vehicles and the rate of change thereof, a quadratic dynamic sliding mode control algorithm is used to generate a speed compensation amount of the slave vehicle; The final speed instructions and the steering control amounts after compensation are sent to the steering wheel actuators of the slave vehicle to drive the motion of the slave vehicle, so as to realize the cooperative linkage with the master vehicle.

2. The AGV double vehicle linkage adaptive motion control method according to claim 1, characterized in that, The step of sending the overall motion instructions with time stamps from the master vehicle to the slave vehicle comprises: The master vehicle controller generates and stores a target speed array queue for a future period of time at a fixed cycle, and each array element is provided with an accurate time stamp; The target speed array queue is sent to the slave vehicle through wireless communication.

3. The AGV double vehicle linkage adaptive motion control method according to claim 1, characterized in that, The step of receiving the overall motion instructions with time stamps by the slave vehicle and dynamically trimming and interpolating compensating the instructions based on a calculated communication delay to generate target speed instructions synchronized with the motion state of the master vehicle comprises: The slave vehicle calculates the total communication delay time according to the time of receiving data; The received speed array queue is dynamically trimmed according to the total communication delay time, and the outdated instruction elements are deleted; The first element of the trimmed queue is linearly interpolated to calculate the synchronized target speed instructions accurately matched with the current time.

4. The AGV double vehicle linkage adaptive motion control method according to claim 1, characterized in that, The step of calculating the steering control amounts of the steering wheels of the slave vehicle according to the synchronized target speed instructions and overall pose deviations comprises: The steering control amounts are calculated by mapping based on the deviation function of the overall pose of the virtual rigid body model and the actual pose of the slave vehicle; the steering control amounts include steering angles of the steering wheels of the slave vehicle, and the calculation of the steering angles makes the steering of the slave vehicle consistent with the motion trajectory of the master vehicle.

5. The AGV double vehicle linkage adaptive motion control method according to claim 1, characterized in that, The step of generating a speed compensation amount of the slave vehicle based on the actual distance error between the double vehicles and the rate of change thereof by using a quadratic dynamic sliding mode control algorithm comprises: A sliding mode surface integrating the quadratic terms of the distance error and the rate of change thereof is constructed; The speed compensation amount of the slave vehicle is dynamically calculated and output according to the sliding mode surface and its trend.

6. The AGV double vehicle linkage adaptive motion control method according to claim 5, characterized in that, In the step of constructing the sliding mode surface integrating the quadratic terms of the distance error and the rate of change thereof, the function expression of the sliding mode surface contains the rate of change of the error, the first-order term and the quadratic term of the error; the coefficients of the first-order term and the quadratic term are determined through system stability analysis to ensure that the sliding mode surface has a dynamic convergence characteristic.

7. The AGV dual vehicle linkage adaptive motion control method according to claim 1, wherein, Further comprising a dynamic adjustment step of the distance between the double vehicles, specifically: The target distance between the double vehicles is determined according to the length of the target material to be carried; The current distance is gradually adjusted to the target distance at a preset maximum step to avoid motion impact.

8. The AGV dual vehicle linkage adaptive motion control method of claim 1, wherein, Further comprising a pose feedback optimization step, specifically: Real-time estimation of the real pose of the host vehicle by fusing the host vehicle odometer and visual sensor data; Feedback of the estimated real pose of the host vehicle to the trajectory tracking closed loop for optimizing the overall motion command.

9. The AGV dual vehicle linkage adaptive motion control method of claim 1, wherein, Further comprising a safety monitoring step, specifically: Real-time interaction of safety interlocking signals between the host vehicle and the follower vehicle; According to the received safety signal level, trigger the corresponding control mode switching including deceleration, stop or emergency stop.

10. An AGV double vehicle linkage adaptive motion control system, characterized in that, Comprise: A virtual rigid body modeling module for constructing a virtual rigid body motion model of the eight steering wheels, which maps the eight steering wheels of the host vehicle and the follower vehicle to a rigid overall model with the midpoint of the double-vehicle connection as the center; A host vehicle control module for the host vehicle to generate the overall motion command of the virtual rigid body model according to the preset motion trajectory, and to calculate the target motion state of each steering wheel based on the model; A wireless communication module for the host vehicle to send the overall motion command with timestamp to the follower vehicle; A delay compensation module for the follower vehicle to receive the overall motion command with timestamp, and to dynamically crop and interpolate the command based on the calculated communication delay to generate a target speed command synchronized with the motion state of the host vehicle; A steering calculation module for the follower vehicle to independently calculate the steering control amount of its steering wheel according to the synchronized target speed command and the overall pose deviation; A sliding mode compensation control module for generating the speed compensation amount of the follower vehicle based on the actual distance error between the double vehicles and its rate of change using a second-order dynamic sliding mode control algorithm; A steering wheel execution module for issuing the final speed command and steering control amount after compensation to the steering wheel execution mechanism of the follower vehicle to drive the motion of the follower vehicle to realize the coordinated linkage with the host vehicle.

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