A heavy workpiece-based rotary feeding and discharging method and system

Abstract

The application provides a heavy workpiece-based rotary feeding and discharging method and system, the rotary feeding and discharging method comprising: obtaining target space parameters; generating a work trajectory based on the target space parameters, the work trajectory comprising an avoidance stage and a synchronous adjustment stage; calculating translation instructions of a pallet unit, rotation instructions of a turret base unit and a rotating fork unit according to each trajectory point contained in the work trajectory; limiting intermediate operation parameters within a preset valid value interval and determining a unique rotation direction during calculation of the rotation instructions; obtaining cantilever load characteristic parameters of the rotating fork unit, calculating a height compensation value; and driving each unit to act to complete feeding and discharging. Through two-stage work trajectory design, the application realizes linear and smooth positioning of the fork by synchronous action, greatly reduces the dynamic rotation boundary of heavy workpieces, effectively avoids collision and interference of narrow workstations, and improves the spatial adaptation capability of the equipment to limited industrial scenes.

Description

Technical Field

[0001] This invention relates to the field of intelligent logistics technology for heavy workpieces, and specifically to a rotary loading and unloading method and system for heavy workpieces. Background Technology

[0002] With the widespread application of modern flexible manufacturing systems in the automotive, aerospace, and heavy equipment industries, the load capacity, positioning accuracy, and system stability of logistics scheduling equipment such as RGV carts have become key factors restricting production efficiency. In workstation transitions involving heavy workpieces, due to the extremely large total mass of the workpiece and pallet, traditional linear RGVs are gradually failing to meet the demands in terms of space utilization and layout flexibility. Rotary RGVs, with their smaller turning radius and more flexible machine tool docking capabilities, have become a research hotspot in the industry.

[0003] In existing material handling equipment control technologies, there have been some studies on kinematic calculation and path planning. For example, Chinese patent application CN108405666A discloses an auxiliary robot for metal sheet processing, which achieves assisted sheet processing through the linkage of components such as the base, upper arm, and forearm, and provides joint angle calculation formulas based on arctangent and inverse cosine functions. However, this solution is mainly aimed at lightweight sheet metal, and its mechanical structure and control algorithm do not take into account the physical deflection and sinking caused by heavy loads when the forks extend. When facing heavy loads, it is very easy for the end-joint to fail or collide due to deformation.

[0004] For example, Chinese patent application CN119096344A discloses a control device for a substrate transport robot, which focuses on using sensors to detect the substrate position to optimize the transport path. Although this solution improves the smoothness of transport, its trajectory planning logic is usually based on an ideal open space and fails to solve the interference problem caused by the excessive rotation radius of long, heavy workpieces in narrow industrial workstations.

[0005] Specifically, existing heavy-duty rotary conveying equipment has the following technical problems in practical applications: 1. When traditional rotary equipment enters a workstation located on the side of the track, it usually adopts a logic of first translating and then rotating or rotating in place. For long and heavy workpieces, this method produces a very large dynamic maximum rotation boundary, which is very easy to collide with the columns around the track or adjacent equipment; 2. When the rotary fork extends under load, due to the physical characteristics of the cantilever beam, the fork tip will sink nonlinearly and produce deflection deformation as the extension length increases. Existing kinematic algorithms are mostly based on rigid models and ignore this physical deviation, which causes the fork to collide or fail to insert into the positioning hole due to height error when entering the loading and unloading station; 3. When the PLC controller commonly used in industrial sites performs linkage calculations, if the input target coordinates are in the extreme pose, its inverse cosine and other trigonometric function calculations are very prone to floating-point overflow, causing the controller to crash or abruptly change action, which seriously affects the safety of heavy-duty equipment operation. Summary of the Invention

[0006] This invention provides a rotary loading and unloading method and system for heavy workpieces, which solves the technical problems of existing heavy-duty rotary handling equipment, such as excessive rotation envelope leading to interference, cantilever deflection causing docking failure, and computational overflow causing equipment failure, resulting in low efficiency for heavy workpieces.

[0007] To address the aforementioned problems, this invention provides a rotary loading and unloading method for heavy workpieces, utilizing a track unit, a pallet unit, a turret base unit, a vertical shaft unit, a lifting pallet unit, and a rotating fork unit. The rotary loading and unloading method includes: Obtain the target spatial parameters of the heavy workpiece at the target workstation; The operation trajectory is generated based on the target space parameters. The operation trajectory includes a collision avoidance phase, a synchronous adjustment phase that moves the rotating fork unit into or out of the target workstation, and a collision avoidance phase that cooperates with the synchronous adjustment phase. Based on the trajectory points contained in the operation trajectory, calculate the translation command of the pallet unit, the first rotation command of the turret base unit, and the second rotation command of the rotating fork unit. During the process of solving rotation commands, intermediate calculation parameters are restricted to a preset valid value range, and a unique rotation direction is determined by combining the orientation characteristics of the target space parameters. Obtain the cantilever load characteristic parameters of the rotating fork unit, calculate the height compensation value, and generate the vertical drive command of the vertical axis unit in combination with the target space parameters; All instructions are synchronized to the actuators, driving each unit to complete the loading and unloading of materials.

[0008] This application, through the coordinated operation of the pallet unit, turret base unit, and rotating fork unit, achieves dynamic geometric folding and flattening of the equipment in confined spaces, significantly reducing the maximum turning radius during operation and improving maneuverability and positioning safety within restricted spaces. Furthermore, the specific avoidance phase of the operating trajectory includes: Move the pallet unit along the track unit to the preset area; The turret base unit is controlled to rotate in the first rotation direction, and the rotating fork unit is simultaneously controlled to rotate in the second rotation direction opposite to the first rotation direction, so that the extension direction of the rotating fork unit is perpendicular to the lifting pallet unit. The vertical axis unit controls the lifting pallet unit to move to the height coordinate corresponding to the target workstation.

[0009] Furthermore, the specific components of the synchronization adjustment phase include: The control pallet unit moves along the track unit toward the coordinates corresponding to the target workstation, and simultaneously controls the turret base unit to rotate in the second rotation direction until the line connecting the rotation center of the turret base unit and the rotating fork unit is parallel to the track unit on the top projection plane, and the extension direction of the rotating fork unit is perpendicular to the track unit. The control pallet unit continues to move along the direction corresponding to the target workstation coordinates, and simultaneously controls the turret base unit to continue rotating in the second rotation direction, while the rotating fork unit rotates in the first rotation direction, moving the rotating fork unit in a direction perpendicular to the track unit to the target workstation.

[0010] Furthermore, before the avoidance phase begins, the system is in its initial state, with the length direction of the lifting pallet unit and the rotating fork unit parallel to the track unit.

[0011] Furthermore, the intermediate calculation parameters are restricted to a preset valid value range, and a unique rotation direction is determined by combining the orientation characteristics of the target spatial parameters. Specifically, this includes: The initial cosine value of the joint is calculated based on the horizontal trajectory component as an intermediate calculation parameter. When the intermediate calculation parameter exceeds the valid value range of -1 to 1, the intermediate calculation parameter is set to the nearest boundary value of 1.0 or -1.0 to obtain a safe cosine value, and the second rotation command is solved based on the safe cosine value. Extract the positive and negative signs of each component in the target space parameters as orientation features, and call the bivariate four-quadrant arctangent function to calculate the basic rotation angle, outputting a unique rotation direction and the first rotation command.

[0012] Further, the height compensation value is calculated, specifically including: Extract the horizontal extension length L and the weight W of the heavy workpiece from the characteristic parameters of the cantilever load; The height compensation value ΔZ is calculated using the following formula:

[0013] Where k is the compensation coefficient preset based on the structural stiffness of the rotating fork unit; The height compensation value ΔZ is superimposed on the initial pose height Z0 of the vertical axis unit to generate the vertical drive command Z. cmd :

[0014] Furthermore, before synchronizing the verified instructions to the actuator, the process also includes: Each instruction is compared with the preset limit travel boundary of the corresponding unit; When any command is detected to exceed the preset limit travel boundary, the synchronization command is stopped and the brakes of each actuator are triggered to lock.

[0015] The present invention also provides a rotary loading and unloading system for heavy-duty workpieces, comprising: Track unit; The pallet unit is slidably mounted on the track unit; The turret base unit is mounted on the support plate unit; The vertical axis unit is mounted on the turret base unit; The lifting tray unit is driven to lift by a vertical shaft unit. A rotating fork unit is mounted on the lifting pallet unit; The main control unit, which is communicatively connected to the above-mentioned units, is configured to execute the above-mentioned rotary loading and unloading method.

[0016] Furthermore, in the initial retracted state, the rotation center of the rotating fork unit is offset to one side of the rotation center of the turret base unit; a cross roller slewing bearing is provided between the turret base unit and the pallet unit.

[0017] Furthermore, both the turret base unit and the rotating fork unit are equipped with absolute encoders; the end of the rotating fork unit is equipped with a pressure sensing component, which is used to collect the weight parameters of heavy workpieces and send them to the main control unit.

[0018] The technical advantages of this application are as follows: This invention employs a two-stage operational trajectory design, abandoning the traditional step-by-step operational logic. Relying on synchronous movements, it achieves smooth, linear fork insertion, significantly reducing the dynamic rotation envelope of heavy-duty workpieces and effectively avoiding collisions and interference in narrow workstations, thus enhancing the equipment's spatial adaptability to constrained industrial environments. Simultaneously, by calculating the height compensation value in real-time using cantilever load, it automatically compensates for height, offsetting the nonlinear sinking caused by heavy fork loads. This solves the height docking deviation problem of traditional rigid models, avoiding collisions, jamming, and other malfunctions, and improving docking accuracy under heavy-duty conditions. Furthermore, this invention determines a unique rotation direction by limiting the range of computational parameters, fundamentally avoiding equipment malfunctions and collision risks caused by controller overflow and incorrect rotation direction, ensuring the stability and reliability of equipment operation, and significantly improving the equipment's operational versatility. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the rotary loading and unloading mechanism for heavy workpieces used in this invention.

[0020] Figure 2 This invention provides a simplified diagram of the projection state structure of step S21 in the avoidance phase of the operation trajectory.

[0021] Figure 3 This invention provides a simplified diagram of the projection state structure of step S22 in the avoidance phase of the operation trajectory.

[0022] Figure 4 This invention provides a simplified diagram of the projection state structure of step S24 in the synchronous adjustment stage of the work trajectory.

[0023] Figure 5 This invention provides a simplified diagram of the projection state structure of step S25 in the synchronous adjustment stage of the work trajectory.

[0024] Figure 6 This is a coordinate system diagram of the planar kinematics model provided by the present invention.

[0025] Explanation of reference numerals in the attached figures: 100. Heavy workpieces; 200 target workstations 1. Track unit; 2. Pallet unit; 3. Turret base unit; 4. Vertical shaft unit; 5. Lifting pallet unit; 6. Rotating fork unit. Detailed Implementation

[0026] The following will be combined with the appendix Figures 1-6 The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0027] This invention relates to the field of intelligent logistics technology for heavy workpieces, specifically to a rotary loading and unloading method and system based on the loading and unloading of heavy workpieces, which solves the technical problems of existing heavy-duty rotary handling equipment, such as excessive rotation envelope leading to interference, cantilever deflection causing docking failure, and computational overflow causing equipment failure, resulting in low efficiency for heavy workpieces.

[0028] The hardware architecture of this embodiment provides an execution platform for the rotary loading and unloading method, as shown in the attached diagram. Figure 1 It includes a track unit 1, a pallet unit 2, a turret base unit 3, a vertical shaft unit 4, a lifting pallet unit 5, a rotating fork unit 6, and supporting sensing and driving components, arranged in sequence. The specific implementation structure of each unit is as follows: The track unit 1 serves as the travel reference for the entire system and includes parallel load-bearing guide rails and a transmission rack. The load-bearing guide rails are heavy-duty linear guide rails, fixed to the industrial workshop floor foundation with anchor bolts, suitable for the load requirements of heavy workpieces. The transmission rack is arranged parallel to the load-bearing guide rails and is used to cooperate with the pallet unit 2 to achieve precise translational drive. In an optional embodiment, limit blocks and hard limit switches are provided at both ends of the track unit 1 to limit the extreme travel positions of the pallet unit 2 and avoid the risk of derailment.

[0029] The pallet unit 2 is slidably mounted on the track unit 1. Its bottom is equipped with a heavy-duty slider assembly that cooperates with the load-bearing guide rail, and a drive gear that meshes with the transmission rack. The drive gear is driven by a travel drive motor fixedly mounted on the pallet unit 2. The travel drive motor is a heavy-duty servo motor with a power-off brake to ensure stability during start-stop and braking safety under heavy load conditions.

[0030] The pallet unit 2 is equipped with a positioning sensor for reading the absolute position. The positioning sensor adopts a grating ruler reading head or a magnetic grating ruler reading head. The track unit 1 is equipped with a corresponding grating ruler strip or magnetic grating ruler strip to collect the absolute translation coordinates of the pallet unit 2 on the track unit 1 in real time. The translation positioning accuracy can reach ±0.1mm.

[0031] The turret base unit 3 is mounted on the support plate unit 2, and a cross roller slewing bearing is provided between the two. The inner ring of the cross roller slewing bearing is fixedly connected to the upper surface of the support plate unit 2 by high-strength bolts, and the outer ring is fixedly connected to the base body of the turret base unit 3. It can simultaneously withstand radial, axial and overturning moments, and is suitable for heavy-load working conditions when heavy workpieces rotate.

[0032] The turret base unit 3 is also equipped with a base rotation drive motor, which is connected to the outer ring of the cross roller slewing bearing through a high-precision reducer, and is used to drive the turret base unit 3 to rotate 360° around its own rotation center in the horizontal plane; the turret base unit 3 is equipped with a first absolute encoder, which is connected to the outer ring of the cross roller slewing bearing, and is used to collect the absolute rotation angle of the turret base unit 3 in real time.

[0033] The vertical shaft unit 4 is fixedly mounted on the turret base unit 3 and rotates synchronously with the turret base unit 3. It includes a vertically arranged heavy-duty lifting screw pair, a lifting drive motor, and a vertical guide rail assembly. The lifting drive motor is a servo motor with a power-off brake, which is connected to the lifting screw pair for transmission and is used to drive the lifting pallet unit 5 to move up and down along the vertical guide rail assembly. Limit switches are provided at the top and bottom of the vertical shaft unit 4 to limit the extreme lifting stroke of the lifting pallet unit 5 and avoid the risk of overtravel.

[0034] One side of the lifting pallet unit 5 is fixedly connected to the slider of the vertical guide rail assembly of the vertical shaft unit 4, and is also fixedly connected to the nut seat of the lifting screw pair. The vertical shaft unit 4 drives the vertical lifting to achieve vertical lifting, providing a stable installation reference for the rotating fork unit 6.

[0035] The rotating fork unit 6 is located at the end of the lifting pallet unit 5 and includes a fork body and a fork rotation drive motor. The fork body is rotatably mounted on the lifting pallet unit 5 via a slewing bearing, and the fork rotation drive motor is connected to the slewing bearing via a reducer to drive the fork body to rotate around its own rotation center in the horizontal plane.

[0036] The rotating fork unit 6 is equipped with a second absolute encoder, which is connected to the slewing bearing of the fork body for real-time acquisition of the absolute rotation angle of the rotating fork unit 6. The end of the rotating fork unit 6 is equipped with a pressure sensing component, which adopts an array structure composed of multiple load cells for acquiring the weight parameters of heavy workpieces placed on the fork body.

[0037] The rotary loading and unloading method based on heavy workpieces provided by this invention is applied to the above-mentioned loading and unloading hardware architecture. It solves the rotation interference problem through two-stage operation trajectory planning, solves the calculation overflow problem through parameter limiting, and solves the height docking error problem through load-related deflection compensation.

[0038] This rotary loading and unloading method includes: Step S1: Pick up the workpiece and obtain the target space parameters of the heavy workpiece 100 at the target station 200; Step S2: Generate a work trajectory based on the target space parameters. The work trajectory includes a synchronous adjustment phase for moving the rotating fork unit 6 into or out of the target workstation 200, and an avoidance phase that cooperates with the synchronous adjustment phase. Step S3: Based on the trajectory points included in the operation trajectory, calculate the translation command of pallet unit 2, the first rotation command of turret base unit 3, and the second rotation command of rotating fork unit 6. Step S4: During the process of solving the rotation command, the intermediate calculation parameters are restricted to a preset valid value range, and the unique rotation direction is determined by combining the orientation characteristics of the target space parameters. Step S5: Obtain the cantilever load characteristic parameters of the rotating fork unit 6, calculate the height compensation value, and generate the vertical drive command of the vertical axis unit 4 in combination with the target space parameters; Step S6: Synchronize all instructions to the actuators to drive each unit to complete the movement and transport the workpiece to the target station.

[0039] This invention employs a two-stage operational trajectory design, abandoning the traditional step-by-step operational logic. Relying on synchronous movements, it achieves smooth positioning along the vertical track during fork rotation, significantly reducing the dynamic rotation envelope of heavy-duty workpieces and effectively avoiding collisions and interference in narrow workstations. This enhances the equipment's spatial adaptability to constrained industrial environments. Simultaneously, by calculating the height compensation value in real-time using cantilever load, it automatically compensates for height, offsetting the nonlinear sinking caused by heavy fork loads. This solves the height docking deviation problem of traditional rigid models, avoiding collisions, jamming, and other malfunctions, and improving docking accuracy under heavy-duty conditions. Furthermore, this invention determines a unique rotation direction by limiting the range of computational parameters, fundamentally avoiding equipment malfunctions and collision risks caused by controller overflow and incorrect rotation direction. This ensures the stability and reliability of equipment operation and significantly improves its operational versatility.

[0040] Specifically, refer to the appendix Figure 1 and 2 Step S1: Obtain the target space parameters of the heavy workpiece 100 at the target station 200. In this step, the heavy workpiece to be transported is first acquired. This heavy workpiece originates from the previous workstation, AGV, or overhead crane. Target spatial parameters include the spatial coordinates of the target workstation 200 relative to the reference origin of the track unit 1. Specifically, these are: the horizontal X-coordinate of the target workstation 200 along the extension direction of the track unit 1, the horizontal Y-coordinate perpendicular to the extension direction of the track unit 1, and the target docking height Z-coordinate. It also includes the azimuth angle of the target workstation 200, the internal dimensions of the workstation, the external dimensions of the heavy workpiece 100, and the positioning hole position parameters. In practice, the target spatial parameters can be pre-entered into the main control unit or acquired in real-time through laser rangefinders and visual positioning devices installed on the system, ensuring consistency between the parameters and the actual working conditions on site.

[0041] Specifically, during the material loading operation, step S2: generate the operation trajectory based on the target space parameters. In this step, the work trajectory includes the avoidance phase and the synchronous adjustment phase of sending the rotating fork unit 6 into the target station 200. It abandons the traditional logic of "first moving into position and then rotating in place" and greatly reduces the maximum rotation boundary of the workpiece movement through the synchronous action of each unit, thus avoiding interference with surrounding equipment.

[0042] Further, refer to the appendix Figure 2 and appendix Figure 3 Before the avoidance phase begins, the system is in its initial state, with the length direction of the lifting pallet unit 5 and the rotating fork unit 6 parallel to the track unit 1. In the initial phase as the actuator approaches the target workstation 200, to prevent the extended portion of the rotating fork unit 6 from easily scraping or interfering with surrounding equipment, the avoidance phase provided in this embodiment involves a pre-adjustment of the position of the rotating fork unit 6 before it enters the target workstation 200. This allows the forks to avoid obstacles around the workstation while simultaneously achieving a pre-positioned height. The specific avoidance phase provided in this embodiment includes: S21: Move pallet unit 2 along track unit 1 to a preset area. This preset area is calculated based on target space parameters and is located on one side of the target workstation 200 along the extension direction of track unit 1. The difference between its X coordinate and the X coordinate of the target workstation 200 is determined according to the length of the rotating fork unit 6 and the Y coordinate of the target workstation to ensure sufficient translational stroke in the subsequent synchronous adjustment stage.

[0043] S22: Control the turret base unit 3 to rotate in the first rotation direction, and simultaneously control the rotating fork unit 6 to rotate in the second rotation direction opposite to the first rotation direction, so that the rotating fork unit 6 is perpendicular to the lifting pallet unit 5. Specifically, during the rotation, the angle of the rotating fork unit 6 rotating clockwise is greater than the angle of the lifting pallet unit 5 deflected with the turret base, so that the angle between the rotating fork unit 6 and the lifting pallet unit 5 changes from parallel 0° to perpendicular 90°. The extension direction of the rotating fork unit 6 changes from the direction toward the track unit 1 to the direction perpendicular to the lifting pallet unit 5 and toward the target workstation 200. The orthogonal projections of the lifting pallet unit 5 and the rotating fork unit 6 on the pallet unit 2 are both contracted to the perimeter of the pallet unit 2, ensuring that during the pre-adjustment rotation, the forks swing away from the target workstation, completely avoiding the area beside the entrance of the target workstation 200, avoiding interference with obstacles such as columns and protective doors around the workstation, and finally making the rotating fork unit 6 perpendicular to the lifting pallet unit 5.

[0044] See attached document Figure 2 and attached Figure 3 In this embodiment, the first rotation direction is counterclockwise, and the second rotation direction is clockwise. Figure 2 As shown, before the avoidance phase begins, both the lifting pallet unit 5 and the rotating fork unit 6 are parallel to the track unit 1, with the rotating fork unit 6 extending towards the side of the track unit 1 in the direction of travel; as Figure 3 As shown, during the avoidance phase, the turret base unit 3 rotates counterclockwise, and the lifting pallet unit 5 deflects counterclockwise accordingly. Simultaneously, the rotating fork unit 6 is controlled to rotate 90° clockwise, that is, the rotating fork unit 6 deflects 90° clockwise relative to the lifting pallet unit 5, so that the rotating fork unit 6 and the lifting pallet unit 5 are perpendicular to each other at 90°. The extension direction of the rotating fork unit 6 changes to face the left side of the pallet unit 2, completely avoiding the area beside the entrance of the target workstation 200. The orthographic projections of the two units on the pallet unit 2 are both contracted to the perimeter range, avoiding the risk of interference.

[0045] S23: Control the vertical axis unit 4 to drive the lifting pallet unit 5 to move to the height coordinate corresponding to the target workstation 200, complete the height pre-positioning of the avoidance stage, and improve the motion stability.

[0046] During the avoidance phase, the turret base and rotating forks are controlled to rotate in opposite directions, causing the mechanism to fold or retract in the horizontal plane, thus moving it away from the target workstation by 200. At the same time, the vertical axis is moved to the target height in advance within a safe distance, minimizing the turning radius and space occupation of the equipment during the movement process, and ensuring that the vertical height adjustment is completed in a safe area without interference.

[0047] Furthermore, within the confined space of the target workstation 200, it is difficult to smoothly and vertically deliver the long, heavy workpiece 100 to the target position using only the turret base unit 3 or the rotating fork unit 6. The synchronous adjustment stage is the main adjustment step for the work trajectory. Through the synchronized coordination of the pallet unit 2's translation, the turret base unit 3's rotation, and the rotating fork unit 6's rotation, the forks are smoothly extended into the target workstation along a straight trajectory, with minimal maximum rotation boundary throughout the entire process, making it suitable for confined workstations. (See attached diagram) Figure 4 , 5 The specific components of the synchronization adjustment stage provided in this embodiment include: S24: Control the pallet unit 2 to move along the track unit 1 towards the direction corresponding to the target workstation 200. This direction is towards the X-coordinate corresponding to the target workstation 200. Simultaneously control the turret base unit 3 to rotate until the line connecting the rotation center of the turret base unit 3 and the rotating fork unit 6 is parallel to the track unit 1 on the top projection plane, and the extension direction of the rotating fork unit 6 is perpendicular to the track unit 1. In this step, the target translation direction is towards the X-coordinate corresponding to the target workstation 200. The main control unit calculates the motion parameters of each axis in real time to ensure that the translation speed of the pallet unit 2 and the rotation angular velocity of the rotating axis are matched, so that the movement trajectory of the fork end in the horizontal plane is always perpendicular to the track unit 1, without lateral swaying, greatly reducing the rotation boundary; when reaching the end position, the extension direction of the fork is completely aligned with the entrance of the target workstation 200, preparing for subsequent extension into the workstation.

[0048] S25: Control the pallet unit 2 to continue moving along the direction corresponding to the coordinates of the target workstation 200, and simultaneously control the turret base unit 3 to continue rotating in the second rotation direction, while the rotating fork unit 6 rotates in the first rotation direction, moving the rotating fork unit 6 into the target workstation. In this step, the rotation directions of the turret base unit 3 and the rotating fork unit 6 are opposite, ensuring that the fork extension direction is always perpendicular to the track unit 1. Simultaneously, through the translation of the pallet unit 2 and the synchronous rotation of the two rotating axes, the fork smoothly extends into the inner cavity of the target workstation 200 along a straight line. The fork swing range is extremely small throughout the process, and the diameter of the rotation boundary circle is only slightly larger than the fork length, completely solving the interference problem caused by the excessively large boundary when rotating long, heavy workpieces.

[0049] In the synchronous adjustment stage, translation and rotation are coordinated to make the line connecting the base and the fork parallel to the track and the fork extension direction perpendicular to the track. Then, the fork enters the work station directly in a straight line, transforming the complex nonlinear spatial approximation process into a relatively simple orthogonal position alignment and straight inward push, reducing the complexity of the control trajectory and reducing the limit reserved space required for entry.

[0050] Because floating-point calculation errors may cause overflow errors in the inverse trigonometric function's operational domain, and the non-uniqueness of rotation direction determination in multiple spatial quadrants may lead to reverse routing of the device, this embodiment further restricts intermediate calculation parameters to a preset valid value range and determines a unique rotation direction by combining the orientation characteristics of the target spatial parameters. Specifically, this includes: The initial cosine value of the joint is calculated based on the horizontal trajectory component as an intermediate calculation parameter. When the intermediate calculation parameter exceeds the valid value range of -1 to 1, the intermediate calculation parameter is set to the nearest boundary value of 1.0 or -1.0 to obtain a safe cosine value, and the second rotation command is solved based on the safe cosine value. Extract the positive and negative signs of each component in the target space parameters as orientation features, and call the bivariate four-quadrant arctangent function to calculate the basic rotation angle, outputting a unique rotation direction and the first rotation command.

[0051] Specifically, based on the trajectory points of the work trajectory, the drive commands for each unit are calculated. (See appendix.) Figure 6 In this step, the main control unit performs inverse kinematics calculations on each trajectory point included in the operation trajectory based on the established planar kinematics model, and obtains the translation command of pallet unit 2, the first rotation command of turret base unit 3, and the second rotation command of rotating fork unit 6.

[0052] The specific kinematic model is as follows: Figure 6 As shown, with the reference origin of track unit 1 as the origin O of the coordinate system, the direction along the track extension is the X-axis, the direction perpendicular to the track pointing to the target work position is the Y-axis, and the vertical upward direction is the Z-axis. The X-axis, Y-axis, and Z-axis form a right-hand rectangular coordinate system. The rotation center coordinates of the turret base unit 3 are (X, 0), where X is the translation coordinate of the pallet unit 2; The fixed distance between the two rotation centers is L0, the rotation angle of the turret base unit 3 is θ1, and θ1 is the first rotation command. Then the coordinates of the rotation center of the rotating fork unit 6 relative to the rotation center of the turret base are (L0・cosθ1, L0・sinθ1). The effective horizontal extension length of the fork is L1, the rotation angle of the rotating fork unit 6 relative to the turret base unit 3 is θ2, and θ2 is the second rotation command. Then the coordinates of the center point of the fork end relative to its own rotation center are (L1・cos(θ1+θ2), L1・sin(θ1+θ2)).

[0053] The final formula for calculating the coordinates of the center point at the end of the fork is as follows:

[0054]

[0055] Based on the target X2 and Y2 of each point on the operation trajectory, the main control unit performs inverse calculations using the above model to obtain the translation command X, the first rotation command θ1, and the second rotation command θ2 for the corresponding trajectory points.

[0056] Optionally, during the calculation of rotation instructions, intermediate calculation parameters are restricted to a preset valid value range, and a unique rotation direction is determined by combining the orientation characteristics of the target space parameters, thus solving the problems of trigonometric function calculation overflow and incorrect rotation direction. Specifically, this includes: S41: Calculate the initial cosine value of the joint based on the horizontal trajectory component as an intermediate calculation parameter. When the intermediate calculation parameter exceeds the valid value range of -1 to 1, set the intermediate calculation parameter to the nearest boundary value of 1.0 or -1.0 to obtain the safe cosine value, and solve the second rotation command based on the safe cosine value.

[0057] In practice, the formula for calculating cosθ2 is obtained through kinematic model transformation:

[0058] The cosθ2 is the intermediate calculation parameter, and its theoretical effective value range is [-1, 1]. However, in industrial settings, rounding errors of target coordinates and sensor acquisition errors can easily lead to calculated values ​​that are slightly greater than 1 or slightly less than -1, triggering overflow of the inverse cosine function calculation, which can cause the controller to crash or suddenly change its action.

[0059] In this embodiment, the effective value range is preset to [-1.0, 1.0]. After calculating cosθ2, a limiting process is first performed: if cosθ2>1.0, it is set to 1.0; if cosθ2<-1.0, it is set to -1.0. After obtaining the safe cosine value, θ2 is solved by arccos(safe cosine value) to avoid the risk of computational overflow.

[0060] S42: Extract the sign of each component in the target space parameters as orientation features, and call the bivariate four-quadrant arctangent function to calculate the basic rotation angle, outputting a unique rotation direction and the first rotation command. Traditional single-variable arctangent functions can only output angles in the interval [-π / 2, π / 2], failing to determine a unique rotation direction and easily leading to reverse rotation of the rotation axis and collisions. This embodiment extracts the signs of the target trajectory points X2 and Y2 as orientation features, and calls the bivariate four-quadrant arctangent function arctan2(Y2, X2) to calculate the basic rotation angle. This function can output angle values ​​in the entire interval [-π, π]. Combining the orientation features, the unique rotation direction is directly determined, avoiding reverse rotation of the rotation axis and ensuring the accuracy of the linked trajectory.

[0061] The cosine value is physically limited to [-1, 1], but small errors in code calculations can cause it to go out of bounds. By forcibly clamping it (returning it to 1.0 or -1.0), the legality of subsequent calculations is guaranteed. By using the bivariate four-quadrant arctangent function, the quadrant is determined directly by the sign of the coordinate system, which avoids the controller crashing due to abnormal underlying mathematical calculations. It outputs the absolutely unique shortest rotation direction, preventing the risk of collisions or cable entanglement caused by the device rotating around a long path.

[0062] When the fork extends to carry a heavy workpiece 100, the elastic deformation of the mechanical structure caused by the cantilever effect will result in the actual height of the workpiece end being lower than the theoretical height. Therefore, this application provides a calculated height compensation value, obtains the cantilever load characteristic parameters of the rotating fork unit, calculates the height compensation value, and combines it with the target space parameters to generate the vertical drive command for the vertical axis unit. This solves the height docking error problem caused by the deflection deformation of the heavy-duty cantilever, specifically including: S51: Extract the horizontal extension length L and the weight W of the heavy workpiece from the characteristic parameters of the cantilever load. Among them, the horizontal extension length L is the horizontal extension distance of the end of the rotating fork unit 6 relative to its own rotation center, which is calculated in real time through the fork structure parameters and rotation angle; the weight W of the heavy workpiece is collected in real time by the pressure sensing component at the end of the rotating fork unit 6.

[0063] S52: Calculate the height compensation value ΔZ using the cantilever beam deflection mechanical model formula: Wherein, k is a preset compensation coefficient constant related to the structural stiffness of the rotating fork unit. The value of k is obtained through pre-conducted mechanical calibration experiments. The calibration method is as follows: the actual sinking of the fork end is measured under unloaded conditions, different extension lengths, and under different standard weights and extension lengths. The accurate value of k is obtained through data fitting to ensure compensation accuracy. This formula perfectly matches the deflection deformation law of cantilever beams, that is, the deflection is proportional to the load and proportional to the cube of the extension length, and can compensate for the deformation sinking under different working conditions.

[0064] S53: Superimpose the height compensation value ΔZ onto the initial pose height Z0 of the vertical axis unit to generate the vertical drive command Z. cmd :

[0065] The longer the fork extension and the heavier the workpiece, the greater the deflection and the greater the height compensation value. The vertical shaft unit 4 drives the lifting pallet unit 5 to lift the corresponding compensation amount, which offsets the sinking of the fork end and ensures that the actual height of the fork end is always consistent with the target height of the target workstation, thus completely solving the docking failure and impact problems caused by the deflection of the heavy-duty cantilever.

[0066] This height compensation value is based on the bending moment principle generated by gravity. It extracts the two key parameters that determine the amount of sag: the weight of the workpiece and the horizontal extension length. Combined with the structural stiffness constant, the actual deviation is obtained. The deviation is then superimposed on the initial drive command through a formula, realizing height feedforward compensation before physical deformation occurs. This offsets the Z-axis positioning error caused by the heavy load sag of the cantilever, ensuring the levelness and height accuracy of the heavy workpiece when it is in place.

[0067] Abnormal target parameters or calculation instructions may cause the mechanism to exceed its physical limits, potentially leading to mechanical structural tearing or collisions. Therefore, before synchronizing the verified instructions to the actuators, a safety verification step is performed, specifically including: S61: Compare each instruction with the preset limit travel boundary of the corresponding unit. Among them, the translation instruction corresponds to the preset limit travel boundary of pallet unit 2, the first rotation instruction corresponds to the preset limit rotation angle boundary of turret base unit 3, the second rotation instruction corresponds to the preset limit rotation angle boundary of rotating fork unit 6, and the vertical drive instruction corresponds to the preset limit lifting travel boundary of vertical shaft unit 4. All limit travel boundaries are pre-entered into the main control unit based on the equipment mechanical structure and workshop obstacle layout.

[0068] S62: When any command is detected to exceed the preset limit travel boundary, the synchronization command is immediately stopped, and the brakes of all actuators are triggered to lock. At the same time, the main control unit triggers an audible and visual alarm to notify the operator and prevent accidents caused by equipment over-travel. After all commands pass the safety verification, the main control unit sends each command synchronously to the corresponding servo driver through the industrial bus, controlling each unit to coordinate synchronously and complete the loading or unloading of heavy workpieces according to the preset work trajectory.

[0069] The rotary loading and unloading method provided in this embodiment supports multiple operating modes: single-stage loading mode, which only performs the loading operation of sending the heavy workpiece 100 into the target station 200, suitable for empty-load loading scenarios; single-stage unloading mode, which only performs the unloading operation of taking the heavy workpiece 100 out of the target station 200, suitable for fully loaded station unloading scenarios; and reverse-order loop mode, which first performs the loading operation to send the heavy workpiece into the target station, and then performs the unloading operation in reverse order to take the heavy workpiece out of the target station and return it to the initial position, suitable for complete loading and unloading loop scenarios. By flexibly selecting the operating mode, this invention can adapt to different industrial production cycle requirements.

[0070] Continue to refer to the appendix Figure 1 This embodiment also provides a rotary loading and unloading system based on heavy-duty workpieces, including a track unit 1, a pallet unit 2, a turret base unit 3, a vertical shaft unit 4, a lifting pallet unit 5, a rotating fork unit 6, and a main control unit.

[0071] The pallet unit 2 is slidably mounted on the track unit 1 and can reciprocate linearly along the extension direction of the track unit 1. The turret base unit 3 is fixedly mounted on the upper surface of the pallet unit 2 and can move synchronously with the pallet unit 2, while also rotating around its own rotation center in the horizontal plane. The vertical shaft unit 4 is fixedly mounted on the turret base unit 3 and can rotate synchronously with the turret base unit 3. The lifting pallet unit 5 is connected to the vertical shaft unit 4 and is driven by the vertical shaft unit 4 to move up and down in the vertical direction. The rotating fork unit 6 is located at the extended end of the lifting pallet unit 5 and can move up and down synchronously with the lifting pallet unit 5, while also rotating around its own rotation center in the horizontal plane. The main control unit is communicatively connected to the track unit 1, pallet unit 2, turret base unit 3, vertical shaft unit 4, lifting pallet unit 5, and rotating fork unit 6 via a real-time industrial bus. The main control unit is configured to execute the rotary loading and unloading method disclosed in this invention. By sequentially configuring multi-degree-of-freedom actuators for the X, Y, and Z axes, and using the main control unit as the central control method, a complete heavy-duty automatic loading and unloading physical architecture is formed, realizing a software and hardware closed loop of kinematic calculation and physical execution.

[0072] Because the heavy cantilever load generates a large overturning moment on the slewing base, and the coaxial design results in a still large overall size even when the equipment is retracted, the rotation center of the rotating fork unit 6 is offset to one side of the rotation center of the turret base unit 3 in the initial retracted state. A cross roller slewing bearing is provided between the turret base unit 3 and the pallet unit 2 to bear the heavy rotational load of the turret base unit. The offset design allows the forks to better fit the spindle when folded, reducing the outer dead angle. The cross roller bearing can simultaneously withstand radial force, axial force, and a strong overturning moment, compressing the planar profile volume of the equipment in the standby or avoidance state, and significantly improving the rigidity and stability of the base against the overturning of heavy-load forks.

[0073] Traditional incremental encoders require a return to the origin after a power outage, resulting in long positioning times and high risks. Furthermore, the main control unit cannot adaptively acquire the weight of different workpieces for deformation compensation. To address this, both the turret base unit 3 and the rotating fork unit 6 are equipped with absolute encoders to collect the absolute rotation angles of the two units in real time and send them to the main control unit. A pressure sensor is installed at the end of the rotating fork unit 6 to collect the weight parameters of the heavy workpiece 100 placed on it and send these parameters to the main control unit. Through the absolute encoders and pressure sensor, the system achieves rapid recovery without returning to zero after a power outage, while also enabling the system to automatically identify the load and perform closed-loop adaptive height compensation.

[0074] When heavy equipment moves along long-distance tracks, traditional belt or friction wheel drives are prone to slippage and cumulative positioning errors over long distances. Furthermore, the track unit 1 provided in this embodiment includes parallel load-bearing guide rails and a transmission rack; the bottom of the pallet unit 2 is equipped with a drive gear that meshes with the transmission rack of the track unit to drive the pallet unit to translate along the track unit; the pallet unit 2 is equipped with a positioning sensor for reading its absolute position, and the positioning sensor is communicatively connected to the main control unit to send the real-time position data of the pallet unit 2 to the main control unit. The track unit 1 ensures the transmission reliability and high translational accuracy of the pallet unit 2 under heavy-load start-stop conditions, eliminating the cumulative errors caused by mechanical transmission backlash and slippage.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A rotary loading and unloading method for heavy workpieces, comprising a track unit, a pallet unit, a turret base unit, a vertical shaft unit, a lifting pallet unit, and a rotating fork unit, characterized in that, The rotary loading and unloading method includes: Pick up the workpiece and obtain the target spatial parameters of the heavy workpiece at the target station; The operation trajectory is generated based on the target space parameters. The operation trajectory includes a synchronous adjustment phase for moving the rotating fork unit into or out of the target workstation and an avoidance phase that cooperates with the synchronous adjustment phase. Based on the trajectory points included in the operation trajectory, calculate the translation command of the pallet unit, the first rotation command of the turret base unit, and the second rotation command of the rotating fork unit; In the process of solving the rotation command, the intermediate calculation parameters are restricted to a preset valid value range, and a unique rotation direction is determined by combining the orientation characteristics of the target space parameters. Obtain the cantilever load characteristic parameters of the rotating fork unit, calculate the height compensation value, and generate the vertical drive command of the vertical axis unit in combination with the target space parameters; The instructions are synchronized to the actuators, driving the actions of each unit to move the workpiece to the target station; The avoidance phase specifically includes: Move the pallet unit along the track unit to the preset area; The turret base unit is controlled to rotate in a first rotation direction, and the rotating fork unit is simultaneously controlled to rotate in a second rotation direction opposite to the first rotation direction, so that the extension direction of the rotating fork unit is perpendicular to the lifting pallet unit, and the orthogonal projections of the lifting pallet unit and the rotating fork unit on the pallet unit are both located within the perimeter of the pallet unit. The vertical axis unit is controlled to drive the lifting pallet unit to move to the height coordinate corresponding to the target workstation; The specific components of the synchronization adjustment phase include: Control the pallet unit to move along the track unit toward the coordinates corresponding to the target workstation, and simultaneously control the turret base unit to rotate in the second rotation direction until the line connecting the rotation center of the turret base unit and the rotating fork unit is parallel to the track unit on the top projection plane; The pallet unit is controlled to continue moving along the direction corresponding to the coordinates of the target workstation, and the turret base unit is simultaneously controlled to continue rotating in the second rotation direction, while the rotating fork unit rotates in the first rotation direction, so that the rotating fork unit is moved into the target workstation along the direction perpendicular to the track unit. The calculation of the height compensation value specifically includes: Extract the horizontal extension length L and the weight W of the heavy workpiece from the characteristic parameters of the cantilever load; The height compensation value ΔZ is calculated using the following formula: ； Wherein, k is a compensation coefficient preset based on the structural stiffness of the rotating fork unit; The height compensation value ΔZ is superimposed on the initial pose height Z0 of the vertical axis unit to generate the vertical drive command Z. cmd : 。 2. The rotary loading and unloading method for heavy workpieces according to claim 1, characterized in that, Before the avoidance phase begins, the system is in an initial state, and the length direction of the lifting pallet unit and the rotating fork unit is parallel to the track unit.

3. The rotary loading and unloading method for heavy workpieces according to claim 1, characterized in that, The step of restricting intermediate calculation parameters to a preset valid value range and determining a unique rotation direction in combination with the orientation characteristics of the target spatial parameters specifically includes: The initial cosine value of the joint is calculated based on the horizontal trajectory component as the intermediate calculation parameter. When the intermediate calculation parameter exceeds the valid value range of -1 to 1, the intermediate calculation parameter is set to the nearest boundary value of 1.0 or -1.0 to obtain a safe cosine value, and the second rotation command is solved based on the safe cosine value. Extract the positive and negative signs of each component in the target space parameters as the orientation feature, and call the bivariate four-quadrant arctangent function to calculate the basic rotation angle, outputting the unique rotation direction and the first rotation command.

4. The rotary loading and unloading method for heavy workpieces according to claim 1, characterized in that, Before synchronizing the verified instructions to the actuator, the process also includes: Each instruction is compared with the preset limit travel boundary of the corresponding unit; When any instruction is detected to exceed the preset limit travel boundary, the synchronization of the instruction is stopped, and the brakes of each actuator are triggered to lock.

5. A rotary loading and unloading system for heavy workpieces, characterized in that, include: Track unit; The pallet unit is slidably mounted on the track unit; A turret base unit is mounted on the support plate unit; A vertical axis unit is mounted on the turret base unit; The lifting tray unit is driven to lift by the vertical shaft unit; A rotating fork unit is mounted on the lifting pallet unit; The main control unit, which is communicatively connected to the aforementioned units, is configured to execute the rotary loading and unloading method as described in any one of claims 1 to 4.

6. The rotary loading and unloading system for heavy workpieces according to claim 5, characterized in that, The rotation center of the rotating fork unit is offset to one side of the rotation center of the turret base unit in the initial retracted state; a cross roller slewing bearing is provided between the turret base unit and the pallet unit.

7. The rotary loading and unloading system for heavy workpieces according to claim 5, characterized in that, Both the turret base unit and the rotating fork unit are equipped with absolute encoders; the end of the rotating fork unit is provided with a pressure sensing component, which is used to collect the weight parameters of the heavy workpiece and send them to the main control unit.

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