Control method and control system of agv transport vehicle for thermal insulation pipe machining

Abstract

The invention discloses a control method and a control system for an agv transport vehicle for thermal insulation pipe machining. The control system comprises a load state sensing module, a gravity center dynamic evaluation module, a path dynamics modeling module, a self-adaptive motion planning module and an execution control module. By integrating a high-precision weighing sensor array, a multi-point displacement detection unit and a clamping jaw pressure sensing array, the full-dimension real-time sensing of the load state of the polyethylene outer sleeve is realized, and the limitation that the prior art only depends on single overload alarm is overcome; a gravity center dynamic evaluation model constructed based on measured data can accurately quantify the mass center offset degree, and a reliable physical basis is provided for subsequent motion planning; according to the provided self-adaptive motion planning mechanism, load dynamic characteristics and path geometric constraints are deeply fused, and pipe body slippage or rolling caused by inertia moment superposition is fundamentally avoided.

Description

Technical Field

[0001] This invention belongs to the field of mechanical manufacturing and automation control technology, specifically relating to a control method and control system for an AGV transport vehicle used in the processing of thermal insulation pipes. Background Technology

[0002] Insulated pipes, as composite pipeline systems integrating media transportation and heat retention, are widely used in key infrastructure such as urban district heating, petrochemicals, district cooling, and industrial steam networks. Their typical structure consists of an inner working steel pipe, a middle high-efficiency insulation layer, and an outer sheath. By suppressing heat loss or external heat intrusion, they ensure stable temperature of the transported medium, improve energy efficiency, and effectively avoid problems such as condensation, frost, and corrosion caused by temperature differences. In the industrial production process of insulated pipes, material handling runs through the entire chain from raw material entry to intermediate component assembly and finished product delivery. This is especially true for the transfer of heavy-duty steel pipes, polyethylene outer sheaths, and molded insulated pipes, placing extremely high demands on the safety, stability, and positioning accuracy of the logistics system. Against this backdrop, automated guided vehicles (AGVs), with their advantages of programmable paths, automated operation, precise positioning, and strong continuous operation capabilities, have gradually replaced traditional manual handling methods. They have become the core equipment for modern insulated pipe production lines to achieve timed, quantitative, and fixed-point material handling, significantly reducing labor intensity and operational risks, and providing key support for intelligent continuous production.

[0003] In the transfer of polyethylene outer sheaths, the current common practice is to use AGV trolleys in conjunction with overhead cranes for hoisting: the overhead crane lifts one or more outer sheaths onto the AGV carrying platform, and the trolley autonomously navigates to the fitting station to complete the subsequent assembly. To prevent axial slippage or radial rolling of the pipes during transportation, existing AGV platforms are usually equipped with hydraulically or electrically driven tilting gripper mechanisms on both sides, which automatically close to physically limit the movement after the pipe is in place. This solution provides basic constraints under uniform linear or static conditions, but faces significant challenges in actual production. This is because the length, wall thickness, and material density of the outer sheath exhibit significant dispersion, resulting in a high degree of randomness in the total mass and center of gravity position after each loading. Furthermore, due to limitations in workshop space and standardized equipment design, the length of the AGV carrying platform is fixed, making it difficult to accommodate all pipe lengths. This causes some extra-long pipes to be cantilevered, further exacerbating the center of gravity shift. Under these conditions, if the preset constant speed curve is still used for start-stop and steering control, it is very easy to exceed the friction limit of the gripper during the acceleration phase due to the superposition of inertial torque and eccentric gravity torque, causing the tube to slip or even roll off. During deceleration or emergency braking, the huge kinetic energy cannot be dissipated smoothly, which will generate a violent impact reaction on the clamping mechanism and the vehicle structure, which not only threatens the integrity of the material, but may also induce equipment vibration instability or navigation accuracy drift.

[0004] Existing control systems generally lack real-time perception and dynamic response capabilities for load status. Although some high-end AGVs are equipped with basic weighing or position detection devices, their data is mostly used only for overload alarms or simple logical judgments, failing to form a closed-loop linkage with the motion control module. The system cannot adaptively reconstruct the acceleration profile, optimize the path curvature, or adjust the braking slope based on the measured total mass, eccentricity, and load distribution pattern, thereby actively suppressing dynamic disturbances while ensuring efficiency. This break in the perception-decision-execution chain means that the transportation process is essentially in an open-loop or weak feedback state, making it difficult to cope with the nonlinear dynamic challenges brought by highly variable loads. Especially in complex path scenarios such as frequent starts and stops, multiple curves, or slopes, the direction of the combined acceleration vector on the tube body continuously changes. Even with sufficient gripper structure strength, it is difficult to avoid the accumulation of micro-displacements caused by instantaneous impact overloads, ultimately affecting the alignment accuracy and assembly yield of the sleeve process. Therefore, there is an urgent need to build an intelligent control architecture that can deeply integrate load feature recognition, dynamic center of gravity assessment and adaptive adjustment of motion parameters, so that AGVs can balance operational safety, work efficiency and energy consumption optimization when facing heavy pipe transportation tasks with significant randomness and eccentricity. This has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention solves the technical problems of existing automated guided vehicles (AGVs) in the transfer of heavy polyethylene outer casing pipes with discrete specifications and significant center of gravity offset by constructing a closed-loop intelligent control architecture that integrates real-time load characteristic perception, dynamic center of gravity assessment and adaptive adjustment of motion parameters. These problems include pipe slippage, rollover and detachment, structural impact and navigation instability caused by the lack of dynamic response capability. It not only ensures the safety and stability of the material transportation process, but also takes into account the optimization of operation efficiency and energy consumption, providing highly robust logistics support for the intelligent manufacturing production line of insulation pipes.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A control method and control system for an AGV transport vehicle used in the processing of thermal insulation pipes; The control method includes: after the polyethylene outer tube is loaded onto the carrying platform of the AGV transport vehicle, the total mass, axial distribution length, cantilever section length and center of gravity offset of the tube are obtained in real time through the load status sensing module. The load status sensing module consists of a high-precision weighing sensor array arranged at the four corners of the carrying platform, a multi-point displacement detection unit arranged along the longitudinal direction of the platform, and a pressure sensing array installed on the inside of the gripper. Based on the data output by the load state perception module, the center of gravity dynamic evaluation module calculates the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body, and outputs a four-dimensional center of gravity state vector containing the total mass, the abscissa of the center of gravity, the ordinate of the center of gravity and the eccentricity angle. Based on the preset navigation path information and real-time environmental data, the path dynamics modeling module establishes a path dynamics model that includes the rate of curvature change, slope gradient, and obstacle constraints. The four-dimensional center of gravity state vector and the path dynamics model are input into the adaptive motion planning module to generate an acceleration profile, velocity upper limit curve and braking slope parameters that match the current load state. The motion parameters are sent to the drive motor controller and steering servo mechanism by the execution control module, so as to realize closed-loop control of the operation status of the automated guided vehicle and continuously monitor the load status during operation to dynamically update the motion planning parameters.

[0007] The method of acquiring the total mass, axial distribution length, cantilever section length, and center of gravity offset of the pipe in real time through the load state sensing module includes: The high-precision weighing sensor array is used to collect the vertical loads borne by the four corners of the supporting platform to determine the total mass; The first laser ranging sensor, the second laser ranging sensor, and the third laser ranging sensor, which are arranged at 500 mm intervals along the center line of the bearing platform by the multi-point displacement detection unit, respectively detect whether the front end of the pipe covers the reference point at the front end of the platform and whether the rear end of the pipe exceeds the boundary of the rear end of the platform, and record the length of the front cantilever and the length of the rear cantilever accordingly. The mass percentage of the cantilever is calculated based on the difference in length between the front and rear cantilever arms and the total length of the tube. The pressure sensor array monitors the normal contact force distribution between the tube and the gripper. When the pressure difference between adjacent sensors exceeds a preset threshold, a secondary locking action of the gripper is triggered.

[0008] The calculation of the composite centroid coordinates of the current load system and its eccentricity vector relative to the vehicle body geometric center by the dynamic evaluation module includes: Based on the readings of the four corner weighing sensors, the two-dimensional coordinates of the centroid of the tube in the vehicle coordinate system are calculated using the static equilibrium equation. By combining the pipe end position measured by the multi-point displacement detection unit, the mass ratio of the cantilever section is derived, and the longitudinal coordinate of the centroid is corrected accordingly. Introduce a cantilever correction factor, calculate the eccentricity angle, and output a four-dimensional centroid state vector containing the total mass, the x-coordinate of the centroid, the corrected y-coordinate of the centroid, and the eccentricity angle.

[0009] The path dynamics model is established by the path dynamics modeling module based on preset navigation path information and real-time environmental data, including: The navigation path is divided into several continuous path segments, each of which is assigned a constant radius of curvature and slope value. Calculate the velocity constraint boundaries at the entrance and exit of each path segment; By integrating data on workshop floor flatness, correction factors for the influence of temperature and humidity on tire friction coefficient, and the position and speed information of dynamic obstacles on the path ahead, the curvature, slope angle, maximum permissible lateral acceleration, and lower limit of emergency braking distance for each path segment are generated.

[0010] The process of inputting the four-dimensional center of gravity state vector and path dynamics model into the adaptive motion planning module to generate acceleration profiles, upper velocity limit curves, and braking slope parameters includes: Based on the direction and magnitude of the eccentric vector, calculate the maximum allowable value of the resultant moment of inertia acting on the pipe on any path segment; Calculate the critical overturning acceleration of the current load on any path segment, and calculate the maximum permissible tangential acceleration. On curved path segments, calculate the maximum permissible lateral acceleration. A piecewise cubic spline interpolation method is used to generate a piecewise continuous upper velocity curve that satisfies dynamic constraints, and the optimal deceleration slope during emergency braking is determined.

[0011] The process of sending motion parameters to the drive motor controller and steering servo mechanism through the execution control module to achieve closed-loop control includes: Adjust the motor output torque in real time to track the target acceleration profile; Send steering angle commands to the steering servo mechanism to ensure that the vehicle travels along the preset path; When the actual operating status deviates from the planned trajectory by more than a preset threshold, a secondary safety strategy is activated, including reduced speed operation, path fine-tuning, or emergency shutdown.

[0012] During emergency braking, the execution control module dynamically adjusts the braking force distribution ratio of each drive wheel according to the current speed, center of gravity height and eccentricity angle, including: prioritizing the increase of braking force on the drive wheel on the side away from the eccentricity direction to generate a reverse stabilizing torque.

[0013] A control system applied to the aforementioned AGV transport vehicle control method for processing thermal insulation pipes includes: The load status sensing module is used to acquire the total mass, axial distribution length, cantilever section length and center of gravity offset of the pipe in real time after the polyethylene outer tube is loaded onto the carrying platform of the AGV transport vehicle. The load status sensing module consists of a high-precision weighing sensor array arranged at the four corners of the carrying platform, a multi-point displacement detection unit arranged along the longitudinal direction of the platform, and a pressure sensor array installed on the inside of the gripper. The center of gravity dynamic evaluation module is used to calculate the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body based on the data output by the load state perception module, and output a four-dimensional center of gravity state vector including total mass, center of gravity abscissa, center of gravity ordinate and eccentricity angle. The path dynamics modeling module is used to establish a path dynamics model that includes curvature change rate, slope gradient and obstacle constraints based on preset navigation path information and real-time environmental data. The adaptive motion planning module is used to receive the four-dimensional center of gravity state vector and path dynamics model, and generate an acceleration profile, velocity upper limit curve and braking slope parameters that match the current load state. The execution control module is used to send the motion parameters to the drive motor controller and the steering servo mechanism to realize closed-loop control of the operation status of the automated guided vehicle, and to continuously monitor the load status during operation to dynamically update the motion planning parameters.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention achieves real-time, multi-dimensional perception of the load status of polyethylene outer sheathing by integrating a high-precision weighing sensor array, a multi-point displacement detection unit, and a gripper pressure sensor array, overcoming the limitations of existing technologies that rely solely on a single overload alarm. The dynamic center of gravity evaluation model built based on measured data can accurately quantify the degree of center of gravity shift, providing a reliable physical basis for subsequent motion planning. The proposed adaptive motion planning mechanism deeply integrates load dynamics characteristics with path geometric constraints, generating a speed control strategy that strictly satisfies overturning stability and friction limits, fundamentally avoiding pipe slippage or rollover caused by the superposition of inertial moments. The dynamic distribution of braking force and the secondary locking mechanism of the grippers introduced in the execution control module further enhance the system's safety redundancy in emergency situations. The overall architecture forms a complete closed loop of perception-evaluation-planning-execution-feedback, enabling the automated guided vehicle to actively adapt to highly variable and strongly eccentric loads, significantly improving the safety, positioning accuracy, and operational efficiency of the insulated pipe transfer process, while reducing equipment structural fatigue damage and energy consumption. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall technical solution architecture of an externally pressurized gas fire extinguishing device and control system with compensation function proposed in this invention. Figure 2 This is a schematic diagram of the core principle framework of the collaborative control of dynamic center of gravity evaluation and adaptive motion planning in this invention; Figure 3 This is a logical flow diagram of the load state sensing module in this invention; Figure 4 This is a flowchart illustrating the logical process of path dynamics modeling and velocity upper limit curve generation in this invention. Figure 5 This is a schematic diagram of the multi-level interaction relationship and data flow between the execution control module and the drive, steering and safety redundancy mechanisms in this invention; Detailed Implementation The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] This invention provides a control method and control system for an AGV (Automated Guided Vehicle) transport vehicle used in the processing of thermal insulation pipes. The aim is to construct a closed-loop intelligent control architecture integrating real-time load status perception, dynamic center of gravity assessment, path dynamics modeling, adaptive motion planning, and execution control. This invention is specifically designed for AGVs transporting heavy-duty polyethylene outer casing pipes with discrete specifications and significant center of gravity shifts. By deeply integrating physical sensor data and motion control strategies, it achieves proactive adaptation to highly variable loads and safe transportation.

[0018] A control method and control system for an AGV transport vehicle used in the processing of thermal insulation pipes; The control system includes: The load status sensing module is used to obtain the total mass, axial distribution length, cantilever section length and center of gravity offset of the pipe in real time after the polyethylene outer tube is loaded onto the carrying platform of the AGV transport vehicle. The center of gravity dynamic evaluation module is used to calculate the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body based on the data output by the load state perception module. The path dynamics modeling module is used to establish a path dynamics model that includes curvature change rate, slope gradient and obstacle constraints based on preset navigation path information and real-time environmental data. The adaptive motion planning module is used to receive the center of gravity state vector and path dynamics model, and generate an acceleration profile, velocity upper limit curve and braking slope parameters that match the current load state. The execution control module is used to send the motion parameters generated by the adaptive motion planning module to the drive motor controller and the steering servo mechanism to realize closed-loop control of the operating status of the automated guided vehicle.

[0019] The control methods include: After the polyethylene outer tube is loaded onto the AGV transport vehicle's carrying platform, the load status sensing module is activated. This module consists of a high-precision weighing sensor array arranged at the four corners of the carrying platform, a multi-point displacement detection unit set along the longitudinal centerline of the platform, and a pressure sensor array embedded in the gripper contact surface. It is used to collect the vertical load borne by the four corners of the platform in real time. The multi-point displacement detection unit adopts the laser ranging principle and is arranged at equal intervals along the centerline of the carrying platform. In this embodiment, it includes a first laser ranging sensor located at the reference point at the front end of the platform, a second laser ranging sensor located at the midpoint of the platform, and a third laser ranging sensor located at the rear end of the platform. The second laser ranging sensor is used to sense whether the longitudinal position of the tube is at the midpoint of the platform. When a single polyethylene outer tube is placed on the platform, the first laser ranging sensor detects whether the front end of the tube is at the midpoint of the platform. The system covers the front reference position of the platform, which is a preset coordinate point. If it is not covered, the length of the front end that is not covered is recorded. The third laser ranging sensor detects whether the rear end of the tube exceeds the rear end boundary of the platform. If it does, the length of the rear end that exceeds the boundary is recorded. The system calculates the mass ratio of the cantilever based on the difference between the lengths of the front and rear cantilever arms and the total length of the tube. The pressure sensor array consists of several pressure sensors embedded in the arc-shaped contact surface of each gripper to monitor the normal contact force distribution between the tube and the gripper. When the pressure value difference output by adjacent sensors exceeds a preset threshold, the system determines that the tube has undergone local micro-displacement and immediately triggers the secondary locking action of the gripper. This secondary locking action is achieved through a hydraulic boosting circuit. In this embodiment, several additional pressures are superimposed on the original clamping force and applied for several seconds to eliminate micro-displacement and restore effective constraint.

[0020] After completing load status perception, the system enters the dynamic center of gravity assessment phase. The dynamic center of gravity assessment module receives data from the weighing sensor array, displacement detection unit, and pressure sensor array, and calculates the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body. Based on the readings of the four corner weighing sensors, this module uses the static equilibrium equation to calculate the two-dimensional horizontal and vertical coordinates of the tube's center of gravity in the vehicle body coordinate system. The formula for calculating the horizontal coordinate of the center of gravity is:

[0021] The x-coordinate of the centroid , , , These are the real-time parameter feedbacks from four weighing sensors: left front, left rear, right front, and right rear. This is the distance between the left and right wheels; The initial formula for calculating the centroid's ordinate is:

[0022] The ordinate of the centroid is y. This refers to the front and rear wheelbase. The longitudinal reference coordinates of the platform's geometric center; When the multi-point displacement detection unit determines that a cantilever segment exists, the system introduces a cantilever correction factor. Its value is determined by the ratio of the cantilever length to the total length of the pipe, and its range is [0, 1]. 0 represents when there is no cantilever section, that is, the cantilever length is 0, and the pipe is completely within the platform, in which case no correction is needed. 1 represents the extreme condition where the entire pipe becomes a cantilever section, that is, the pipe is in contact with the platform at only one end and the rest is suspended in the air. The offset of the center of mass of the cantilever section relative to the end of the platform is denoted as . In this embodiment, half the length of the cantilever segment is taken, and the final corrected centroid ordinate is... The calculation formula is:

[0023] By combining the total mass, the x-coordinate of the center of mass, and the y-coordinate of the corrected center of mass, the system further calculates the eccentricity angle. It outputs a four-dimensional centroid state vector containing the total mass, the x-coordinate of the centroid, the y-coordinate of the centroid, and the eccentricity angle. The calculation formula is:

[0024] The system invokes the path dynamics modeling module to construct a path dynamics model based on preset navigation path information and real-time environmental data. The navigation path is divided into several continuous path segments, each assigned a constant radius of curvature and slope value. The path dynamics modeling module calculates the velocity constraint boundaries at the entrance and exit of each path segment and integrates workshop ground smoothness data, temperature and humidity influence correction factors on tire friction coefficient, and the position and velocity information of dynamic obstacles on the path ahead. Ground smoothness data is obtained through vertical acceleration fluctuation spectrum inversion collected by the vehicle-mounted inertial measurement unit and is used to correct the effective support stiffness of the path segment. Temperature and humidity data are provided by environmental monitoring nodes and are used to dynamically adjust the friction coefficient μ between the tire and the ground. Dynamic obstacle information is obtained through broadcasting from the workshop-level scheduling system and is used to insert temporary deceleration zones or avoidance windows in the path segment. The path dynamics model ultimately outputs the curvature κ, slope angle θ, maximum permissible lateral acceleration alat,limit, and lower limit of emergency braking distance for each path segment. After obtaining the center of gravity state vector and the path dynamics model, the system enters the adaptive motion planning stage. The adaptive motion planning module receives the above two sets of inputs and generates an acceleration profile, upper limit velocity curve, and braking slope parameters that strictly match the current load state. Based on the direction and magnitude of the eccentricity vector, this module calculates the maximum permissible value of the combined inertial moment on the pipe body on any path segment. The system calculates the critical overturning acceleration acrit of the current load on any path segment, the expression of which is:

[0025] It is the acceleration due to gravity. It is the minimum horizontal distance from the center of mass to the boundary of the polygon supporting the vehicle body. The height of the center of gravity is determined by a combination of the pipe diameter, platform height, and gripper lifting amount. The system sets a safety factor k. In this embodiment, k is set to 0.7. Because the safety factor of the center of gravity offset load must be ≥0.65 according to the requirements of the "Safety Specifications for Industrial Vehicles", k is set to 0.7, which not only meets the mandatory specifications, but also adapts to the characteristics of the pipe with a large length-to-diameter ratio and high risk of eccentricity. Maximum permissible tangential acceleration In curved sections, the effect of centrifugal acceleration is further considered, and the maximum permissible lateral acceleration is limited to [value missing]. , The current tangential acceleration, The road surface slope angle; The adaptive motion planning module employs piecewise cubic spline interpolation to generate a piecewise continuous, first-derivative smooth speed limit curve. This curve accelerates to cruising speed with maximum permissible acceleration on straight sections, dynamically reduces the speed limit based on the radius of curvature on curved sections, and adjusts the acceleration or deceleration slope according to the slope direction on sloping sections. Simultaneously, the module calculates the optimal deceleration slope during emergency braking to ensure a safe stop within the shortest distance without causing pipe slippage.

[0026] The execution control module receives motion parameters generated by the adaptive motion planning module and sends them to the drive motor controller and steering servo mechanism to achieve closed-loop control of the automated guided vehicle's (AGV) operating status. The execution control module communicates with the drive motor controller via an industrial Ethernet bus, adjusting the output torque of each drive motor in real time to accurately track the target acceleration profile. It sends steering angle commands to the steering servo mechanism via the CAN bus to ensure the vehicle travels along the preset path, with path tracking errors controlled within ±10 millimeters. During operation, the execution control module continuously receives real-time data streams from the load status sensing module. If the actual operating status deviates from the planned trajectory by more than a preset threshold, such as speed exceeding limits due to sudden ground changes or center of gravity drift caused by micro-displacement of the pipe, the system immediately activates a secondary safety strategy. This secondary safety strategy includes reducing speed to a safe sub-speed for the current path segment, fine-tuning subsequent path segments to avoid high-risk areas, or triggering an emergency stop in extreme cases. During emergency braking, the execution control module dynamically adjusts the braking force distribution ratio of each drive wheel based on the current speed, center of gravity height, and eccentricity angle. Specifically, the system prioritizes increasing the braking force on the drive wheel furthest from the eccentric direction to generate a counter-stabilizing torque and suppress the rollover tendency of the tube due to inertia. The expression for the braking force distribution ratio is as follows:

[0027] The ratio of the braking force of the left-hand drive wheel to the total braking force. It is the baseline equal distribution ratio of braking force between the left and right wheels when there is no eccentricity. It is an off-center angle. To stabilize the gain coefficient, the value range is [0.1-0.3], and it is dynamically adjusted according to the tube mass and cantilever length; The range of values ​​for is [-1, 1], which is an inherent property of trigonometric functions. If... >3, the maximum value of the correction term reaches 0.3, which will cause the extreme value of the braking force ratio of the left drive wheel to be 0.5+0.3=0.8 or as low as 0.5-0.3=0.2, which will lead to an excessively high ratio of braking force on one side, which will exceed the adhesion limit between the wheel and the road surface, causing the wheel on one side to lock up and slip, which will exacerbate the slippage and rollover of the tube; or the braking torque and the eccentric inertial torque will be excessively superimposed in opposite directions, generating additional structural impact loads that exceed the impact resistance threshold of the transport vehicle cantilever.

[0028] Throughout the transportation process, the system forms a complete closed loop of perception, evaluation, planning, execution, and feedback. The load status perception module updates data at preset times, the center of gravity dynamic evaluation module synchronously refreshes the center of gravity state vector, and the adaptive motion planning module recalculates the speed limit curve before each path segment switch. The corresponding execution control module performs low-level control. This closed-loop mechanism enables the automated guided vehicle to actively adapt to highly variable and strongly eccentric loads, fundamentally avoiding problems such as pipe slippage, rollover, structural impact, and navigation instability caused by the superposition of inertial moments. The system not only ensures the safety and stability of the material transportation process, but also reduces unnecessary acceleration and braking energy consumption through refined speed planning, taking into account both operational efficiency and energy optimization, and providing highly robust logistics support for the intelligent manufacturing production line of thermal insulation pipes.

[0029] The working principle of this invention is as follows: Step 1: Load Full-Dimensional Perception Start-up and Data Acquisition After the polyethylene outer casing is hoisted onto the AGV carrying platform by the overhead crane, the system automatically activates the load status sensing module. This module simultaneously collects multi-dimensional load data through three types of sensing components, achieving comprehensive monitoring of the casing's condition. Accurate detection of total mass: A high-precision weighing sensor array arranged at the four corners of the bearing platform synchronously collects the vertical load data of each corner. The total mass of the tube is directly obtained by summing the loads at the four corners, providing basic physical parameters for subsequent dynamic calculations; Pipe position and cantilever segment identification: Several first, second, and third laser ranging sensors are deployed along the longitudinal centerline of the platform to work together: The first sensor detects whether the front end of the pipe covers the front reference point of the platform. If it does not cover it, the length of the front cantilever is recorded. The third sensor detects whether the rear end of the pipe exceeds the rear boundary of the platform. If it does, the length of the rear cantilever is recorded. The second sensor assists in verifying whether the longitudinal center of the pipe is aligned with the midpoint of the platform. At the same time, the cantilever mass percentage is calculated in combination with the preset total length of the pipe. Gripper contact status monitoring: A pressure sensor array installed on the inner arc-shaped contact surface of the gripper monitors the normal contact force distribution between the tube and the gripper in real time. If the pressure difference between adjacent sensors exceeds a preset threshold, it is immediately determined that there is a micro-displacement in the tube and triggers the gripper to lock again.

[0030] Step 2: Dynamic evaluation of center of gravity and output of state vector The center of gravity dynamic evaluation module receives real-time data from the load state perception module, accurately quantifies the load center of gravity characteristics through multi-step calculations, and outputs a four-dimensional center of gravity state vector, providing core physical basis for motion planning: Initial centroid coordinate calculation: Based on the load data of the four corner weighing sensors, the abscissa and initial ordinate of the centroid of the tube in the vehicle coordinate system are calculated using the static equilibrium equation. The abscissa reflects the left-right offset, and the initial ordinate reflects the front-back offset. Longitudinal coordinate correction of centroid: Combining the cantilever segment length measured by the multi-point displacement detection unit, a cantilever correction factor α is introduced to correct the initial longitudinal coordinate of centroid, resulting in a corrected longitudinal coordinate of centroid that better reflects the actual load condition. Eccentricity calculation and vector output: Based on the corrected centroid abscissa and ordinate, the eccentricity angle of the centroid relative to the geometric center of the vehicle body is calculated using the arctangent function. The final output includes: total mass, centroid abscissa, corrected centroid ordinate, and a four-dimensional centroid state vector of eccentricity angle, which fully represents the mass and position characteristics of the load.

[0031] Step 3: Path dynamics modeling and constraint integration The path dynamics modeling module, based on a preset navigation path and incorporating real-time environmental data, constructs a path dynamics model with multiple constraints, clearly defining the operational boundaries of each path segment: Path segmentation and basic parameter assignment: The preset navigation path is divided into several continuous path segments, and each path segment is assigned a constant radius of curvature and slope value to achieve fine-grained path segmentation. Environmental and working condition data integration: Collect three types of key data for model optimization: Collect vertical acceleration fluctuation spectrum through vehicle-mounted inertial measurement unit to invert workshop ground flatness data and correct the effective support stiffness of the path segment; Obtain temperature and humidity data from environmental monitoring nodes to dynamically adjust the friction coefficient μ between the tire and the ground; Obtain the position and speed information of dynamic obstacles on the path ahead through workshop-level scheduling system to plan avoidance windows; Constraint boundary calculation: Combining the path segment parameters and the integrated environmental data, calculate the speed constraint boundaries of the entrance and exit of each path segment, clarify the curvature, slope angle, maximum allowable lateral acceleration and lower limit of emergency braking distance of each path segment, and form a complete path dynamics model.

[0032] Step 4: Adaptive Motion Planning and Parameter Generation The adaptive motion planning module receives the four-dimensional center of gravity state vector and the path dynamics model, and generates motion control parameters adapted to the current load and path through dynamic constraint calculation and optimization algorithms. Calculation of moment of inertia and critical acceleration: Based on the direction and magnitude of the eccentric vector, determine the maximum allowable value of the resultant moment of inertia on the pipe body on any path segment; combine the height of the center of gravity, the minimum horizontal distance from the center of gravity to the vehicle body support boundary, and the acceleration due to gravity to calculate the critical overturning acceleration, and then introduce the safety factor k to obtain the maximum allowable tangential acceleration; in curved sections, further combine the tangential acceleration and the slope angle to calculate the maximum allowable lateral acceleration; Speed ​​curve and braking parameter optimization: A piecewise cubic spline interpolation method is used to generate a piecewise continuous speed upper limit curve with smooth first derivative. On straight road sections, the speed is accelerated to the cruising speed at the maximum allowable acceleration. On curved road sections, the speed is dynamically reduced according to the radius of curvature. On sloping road sections, the acceleration or deceleration slope is adjusted according to the slope direction. At the same time, the optimal deceleration slope during emergency braking is calculated to ensure that the vehicle stops within the shortest safe distance without causing pipe slippage.

[0033] Step 5: Implementing control and closed-loop regulation The execution control module, as the core of the underlying control, transforms the parameters generated by the adaptive motion planning module into specific execution instructions, enabling precise control of the AGV's operating status. Drive and steering control: Adjust the motor output torque in real time to accurately track the target acceleration profile; send steering angle commands to the steering servo mechanism to ensure that the vehicle travels along the preset path; Safety policy triggering and execution: During operation, the system continuously receives real-time feedback from the load status perception module. If the actual operating status deviates from the planned value by more than a preset threshold, a secondary safety policy is immediately activated: for slight deviation, the speed is reduced to the safe sub-speed of the current path segment; for moderate deviation, the subsequent path is finely adjusted to avoid high-risk areas; for severe deviation, an emergency shutdown is triggered. Emergency braking force distribution: During emergency braking, the braking force ratio of the left and right drive wheels is dynamically adjusted according to the current speed, center of gravity height and eccentricity angle. The braking force on the side away from the eccentricity direction is increased first, generating a reverse stabilizing torque to suppress the tendency of the tube to roll.

[0034] Step 6: Dynamic Feedback and Parameter Iteration Throughout the Process Throughout the transportation process, the system maintains a closed-loop operation: the load status perception module continuously updates data according to a preset cycle, and the center of gravity dynamic evaluation module synchronously refreshes the four-dimensional center of gravity status vector; whenever the AGV enters a new path segment, the adaptive motion planning module recalculates parameters such as the upper limit speed curve and acceleration profile based on the latest center of gravity status and environmental data; the execution control module receives the updated planning parameters in real time and dynamically adjusts the drive, steering, and braking strategies to ensure that the AGV always adapts to load changes and path constraints throughout the entire transfer process, achieving safe, accurate, and efficient transportation.

Claims

1. A control method for an AGV transport vehicle used in the processing of thermal insulation pipes, characterized in that, After the polyethylene outer tube is loaded onto the carrying platform of the AGV transport vehicle, the total mass, axial distribution length, cantilever section length and center of gravity offset of the tube are obtained in real time through the load status sensing module. The load status sensing module consists of a high-precision weighing sensor array arranged at the four corners of the carrying platform, a multi-point displacement detection unit arranged along the longitudinal direction of the platform, and a pressure sensor array installed on the inside of the gripper. Based on the data output by the load state perception module, the center of gravity dynamic evaluation module calculates the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body, and outputs a four-dimensional center of gravity state vector containing the total mass, the abscissa of the center of gravity, the ordinate of the center of gravity and the eccentricity angle. Based on the preset navigation path information and real-time environmental data, the path dynamics modeling module establishes a path dynamics model that includes the rate of curvature change, slope gradient, and obstacle constraints. The four-dimensional center of gravity state vector and the path dynamics model are input into the adaptive motion planning module to generate an acceleration profile, velocity upper limit curve and braking slope parameters that match the current load state. The motion parameters are sent to the drive motor controller and steering servo mechanism by the execution control module, so as to realize closed-loop control of the operation status of the automated guided vehicle and continuously monitor the load status during operation to dynamically update the motion planning parameters.

2. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 1, characterized in that, The method of acquiring the total mass, axial distribution length, cantilever section length, and center of gravity offset of the pipe in real time through the load state sensing module includes: The high-precision weighing sensor array is used to collect the vertical loads borne by the four corners of the supporting platform to determine the total mass; The first laser ranging sensor, the second laser ranging sensor, and the third laser ranging sensor, which are arranged at 500 mm intervals along the center line of the bearing platform by the multi-point displacement detection unit, respectively detect whether the front end of the pipe covers the reference point at the front end of the platform and whether the rear end of the pipe exceeds the boundary of the rear end of the platform, and record the length of the front cantilever and the length of the rear cantilever accordingly. The mass percentage of the cantilever is calculated based on the difference in length between the front and rear cantilever arms and the total length of the tube. The pressure sensor array monitors the normal contact force distribution between the tube and the gripper. When the pressure difference between adjacent sensors exceeds a preset threshold, a secondary locking action of the gripper is triggered.

3. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 2, characterized in that, The calculation of the composite centroid coordinates of the current load system and its eccentricity vector relative to the vehicle body geometric center by the dynamic evaluation module includes: Based on the readings of the four corner weighing sensors, the two-dimensional coordinates of the centroid of the tube in the vehicle coordinate system are calculated using the static equilibrium equation. By combining the pipe end position measured by the multi-point displacement detection unit, the mass ratio of the cantilever section is derived, and the longitudinal coordinate of the centroid is corrected accordingly. Introduce a cantilever correction factor, calculate the eccentricity angle, and output a four-dimensional centroid state vector containing the total mass, the x-coordinate of the centroid, the corrected y-coordinate of the centroid, and the eccentricity angle.

4. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 3, characterized in that, The path dynamics model is established by the path dynamics modeling module based on preset navigation path information and real-time environmental data, including: The navigation path is divided into several continuous path segments, each of which is assigned a constant radius of curvature and slope value. Calculate the velocity constraint boundaries at the entrance and exit of each path segment; By integrating data on workshop floor flatness, correction factors for the influence of temperature and humidity on tire friction coefficient, and the position and speed information of dynamic obstacles on the path ahead, the curvature, slope angle, maximum permissible lateral acceleration, and lower limit of emergency braking distance for each path segment are generated.

5. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 4, characterized in that, The process of inputting the four-dimensional center of gravity state vector and path dynamics model into the adaptive motion planning module to generate acceleration profiles, upper velocity limit curves, and braking slope parameters includes: Based on the direction and magnitude of the eccentric vector, calculate the maximum allowable value of the resultant moment of inertia acting on the pipe on any path segment; Calculate the critical overturning acceleration of the current load on any path segment, and calculate the maximum permissible tangential acceleration. On curved path segments, calculate the maximum permissible lateral acceleration. A piecewise cubic spline interpolation method is used to generate a piecewise continuous upper velocity curve that satisfies dynamic constraints, and the optimal deceleration slope during emergency braking is determined.

6. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 5, characterized in that, The process of sending motion parameters to the drive motor controller and steering servo mechanism through the execution control module to achieve closed-loop control includes: Adjust the motor output torque in real time to track the target acceleration profile; Send steering angle commands to the steering servo mechanism to ensure that the vehicle travels along the preset path; When the actual operating status deviates from the planned trajectory by more than a preset threshold, a secondary safety strategy is activated, including reduced speed operation, path fine-tuning, or emergency shutdown.

7. The control method for an AGV transport vehicle used in the processing of thermal insulation pipes according to claim 6, characterized in that, During emergency braking, the execution control module dynamically adjusts the braking force distribution ratio of each drive wheel according to the current speed, center of gravity height and eccentricity angle, including: prioritizing the increase of braking force on the drive wheel on the side away from the eccentricity direction to generate a reverse stabilizing torque.

8. A control system applied to the control method for the AGV transport vehicle used in the processing of thermal insulation pipes according to any one of claims 1 to 7, characterized in that, include: The load status sensing module is used to acquire the total mass, axial distribution length, cantilever section length and center of gravity offset of the pipe in real time after the polyethylene outer tube is loaded onto the carrying platform of the AGV transport vehicle. The load status sensing module consists of a high-precision weighing sensor array arranged at the four corners of the carrying platform, a multi-point displacement detection unit arranged along the longitudinal direction of the platform, and a pressure sensor array installed on the inside of the gripper. The center of gravity dynamic evaluation module is used to calculate the composite center of gravity coordinates of the current load system and its eccentricity vector relative to the geometric center of the vehicle body based on the data output by the load state perception module, and output a four-dimensional center of gravity state vector including total mass, center of gravity abscissa, center of gravity ordinate and eccentricity angle. The path dynamics modeling module is used to establish a path dynamics model that includes curvature change rate, slope gradient and obstacle constraints based on preset navigation path information and real-time environmental data. The adaptive motion planning module is used to receive the four-dimensional center of gravity state vector and path dynamics model, and generate an acceleration profile, velocity upper limit curve and braking slope parameters that match the current load state. The execution control module is used to send the motion parameters to the drive motor controller and the steering servo mechanism, and continuously monitor the load status during operation to dynamically update the motion planning parameters.

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