First plate material centering system and centering method for automobile stamping line

Abstract

The present application belongs to the technical field of automobile stamping automation equipment, and discloses a first plate material centering system and centering method for an automobile stamping line, which comprises a plate material transition conveying device, a centering platform, a visual detection device and a controller. The centering platform is provided with a plate material pose adjusting device, and the centering platform is provided with a platform transmission mechanism. The platform transmission mechanism conveys the plate material to the centering station of the centering platform. The visual detection device comprises a linear array camera, which scans the edge profile of the plate material in real time. The image processing unit of the controller receives the plate material edge profile detection information sent by the linear array camera, extracts the plate material position and angle deviation through a matching algorithm, calculates the inverse kinematics solution of the centering platform in real time, and completes the plate material pose adjustment through the movement of the centering platform. The present application can realize real-time scanning and pose deviation calculation during the continuous transmission of the plate material, improve the centering efficiency and centering accuracy, and is particularly suitable for unmanned production and high-speed continuous transmission scenes in modern intelligent factories.

Description

Technical Field

[0001] This invention belongs to the technical field of automotive stamping automation equipment, specifically relating to a centering system and method for the first sheet of material in an automotive stamping line. Background Technology

[0002] In the field of automotive stamping automation, sheet metal alignment before press loading is a crucial step in ensuring stamping accuracy. Existing technologies typically employ a stop mechanism for alignment, suitable for sheet metal of fixed shapes. However, a single alignment mechanism cannot flexibly adapt to sheet metal of different sizes, such as two small pieces or a single large piece, resulting in insufficient production line flexibility. Furthermore, alignment adjustment time is long, with changeover times reaching 2-4 hours, making it unsuitable for aligning irregularly shaped sheet metal. It also easily scratches the material surface, increasing subsequent polishing costs. While vision alignment systems based on area scan cameras use static imaging to achieve non-contact measurement, they exhibit shortcomings in practical applications. Relying on static imaging of the sheet metal makes it difficult to meet the real-time requirements of high-speed transmission scenarios. In addition, existing technologies often correct sheet metal angular deviations through secondary positioning, leading to extended cycle times.

[0003] Therefore, there is an urgent need for a centering device and method that can synchronously correct the position and angle of sheet metal in real time under continuous belt transmission, so as to improve centering efficiency, reduce centering adjustment time, improve centering accuracy, adapt to the requirements of high-speed continuous transmission scenarios, and solve the problem of position and angle deviation when the sheet metal is loaded at the beginning of the stamping production line. Summary of the Invention

[0004] This invention addresses the aforementioned problems in existing technologies by providing a first-piece sheet alignment system for automotive stamping lines. It utilizes a line-scan camera to scan the conveyed sheet metal contour in real time, combined with a movable and rotatable alignment platform to achieve precise alignment and angle correction. This system enables real-time scanning and calculation of positional deviations during continuous sheet metal transport. The use of dual 3-PRR parallel alignment platforms allows for rapid adaptive adjustment, improving alignment efficiency, reducing adjustment time, and enhancing alignment accuracy. It meets the precise alignment requirements of sheet metals of different sizes, improving product quality and production efficiency, and solving the problem of positional and angular deviations during the loading of the first sheet metal in stamping production lines. It is particularly suitable for unmanned production and high-speed continuous transport scenarios in modern smart factories.

[0005] The present invention also provides a method for centering the first sheet of material in an automotive stamping line.

[0006] The technical solution of this invention to solve the technical problem is: A sheet metal alignment system for an automotive stamping line includes a sheet metal transition conveyor, an alignment platform, a vision inspection device, and a controller. The controller is electrically connected to the sheet metal transition conveyor, the alignment platform, and the vision inspection device. The alignment platform is equipped with a sheet metal posture adjustment device and is arranged adjacent to the sheet metal transition conveyor. A vision inspection device is located above the sheet metal transition conveyor and the alignment platform. The alignment platform is equipped with a platform transmission mechanism that transports the sheet metal to the alignment station on the alignment platform. The vision inspection device includes a line scan camera that scans the edge contour of the sheet metal in real time. The image processing unit of the controller receives the sheet metal edge contour detection information sent by the line scan camera, extracts the position and angle deviation of the sheet metal through a matching algorithm, and calculates the inverse kinematics of the alignment platform in real time. The movement of the alignment platform completes the sheet metal posture adjustment.

[0007] The centering platform includes an X / Y linear motor module and adopts a dual 3-PRR parallel mechanism. Both the single 3-PRR mechanism and the dual 3-PRR mechanism have X / Y translational and θ rotational degrees of freedom to realize dual-material working mode and single-material working mode.

[0008] The dual-material working mode involves two small plates entering two separate 3-PRR mechanisms, with each small plate independently adjusting its position and orientation. The single-material working mode involves a single large plate spanning two 3-PRR mechanisms, achieving overall position and orientation correction and adjustment through coordinated motion.

[0009] The sheet material transition conveying device adopts a belt conveyor mechanism, which includes a transition belt and a belt conveyor mechanism that drives the transition belt to move at a constant speed. The centering platform is equipped with a platform transmission mechanism, which includes a centering belt to transport the sheet material to the centering station of the centering platform.

[0010] The transition belt and centering belt are equipped with vacuum adsorption units at their lower parts, which reliably adsorb the sheet material at the position of the transition conveyor or the centering platform.

[0011] The linear array camera is provided in two or more configurations, which are arranged laterally along the belt and sequentially installed above the transition belt and the centering belt. A method for centering the first sheet of material in an automotive stamping line, using the aforementioned automotive stamping line first sheet of material centering system, includes the following steps: S01: The vision inspection device continuously acquires images of the sheet metal edges and transmits the images back to the controller; S02: The controller processes the image information to obtain the actual pose of the sheet metal, compares it with the standard pose, and obtains the position deviation and angle deviation. S03: Plan the adjustment trajectory of the centering platform, generate a smooth motion curve, and solve the required displacement of each joint of the centering platform based on rigid body kinematics. S04: The controller drives the centering platform to complete multi-axis linkage position adjustment. The sheet metal moves and rotates rigidly with the centering platform to achieve the target posture. S05: Once the sheet material is removed, the centering platform automatically resets, awaiting the next adjustment.

[0012] Before S01, the system initialization phase is carried out, including the establishment and calibration of the equipment coordinate system, the pre-storage of the geometric parameters and standard position information of various standard plates into the control system database, and the completion of the basic parameter configuration and system readiness preparation of the vision inspection unit and the execution unit.

[0013] In S02, the controller pre-stores a coordinate transformation matrix determined by hand-eye calibration. The coordinate transformation matrix describes the coordinate transformation relationship between the image pixel coordinate system and the static coordinate system. When using a single sheet, the static coordinate system is a pre-calibrated absolute rectangular coordinate system fixed to the center of the centering platform. Its XY plane is located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward. When using two sheets, it includes two independent static coordinate systems. The two static coordinate systems are pre-calibrated absolute rectangular coordinate systems at the centers of the left and right surfaces of the centering platform. Their XY planes are both located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward.

[0014] The controller receives the sheet metal edge image scanned by the linear scan camera and reconstructs the sheet metal contour. It then obtains the coordinates of the sheet metal contour points in the static coordinate system through a coordinate transformation matrix and calculates the deviation between the actual position and the standard position of the sheet metal. This pose deviation includes the linear deviation of the sheet metal in the X direction within the static coordinate system. Linear deviation in the X and Y directions Y and rotation angle deviation θ; where, X = X_actual - X_ref, Y = Y_actual - Y_ref θ = θ_actual - θ_ref; (X_actual, Y_actual, θ_actual) is the actual pose of the sheet metal calculated by visual inspection, (X_ref, Y_ref, θ_ref) is the pre-stored standard pose of the sheet metal, and the rotation angle deviation θ is positive in the counterclockwise direction around the Z-axis of the static coordinate system; By fusing continuous sequence scan line data acquired by a linear array camera with high-precision position information fed back in real time by the encoder of the belt conveyor, the local edge image data during the sheet metal movement process is temporally aligned and spatially correlated. Then, the boundary point cloud model of the complete outline of the sheet metal is generated through image stitching and reconstruction technology. Based on the synthesized global image information, a DP-based image registration algorithm is used to perform high-precision matching and comparison between the real-time acquired sheet metal outline and the pre-stored standard outline template, thereby calculating the precise pose deviation of the sheet metal in the planar coordinate system.

[0015] In step S03, when using double plates, based on the left and right pose deviations obtained in step S02, the controller plans the motion trajectory of the left and right platforms of the centering platform from the current pose to the target pose using a seventh-order polynomial, thereby obtaining a smooth motion curve where the position, velocity, acceleration, and jerk are all continuous and the boundary values ​​are zero. Subsequently, based on the kinematic model of the centering platform, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time. When processing single-sheet material, a set of pose deviations is obtained according to step S02. The controller plans the motion trajectory of the entire platform from the current pose to the target pose based on a seventh-order polynomial, thereby obtaining a smooth motion curve in which position, velocity, acceleration, and jerk are all continuous and the boundary value is zero. Subsequently, based on the kinematic model of the platform, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time.

[0016] To ensure the stability and accuracy of the alignment platform's movement and to suppress vibration, the controller employs a seventh-order polynomial programming method for the motion trajectory of the entire alignment platform surface from its current pose to the target pose. The functional expression of the motion trajectory is as follows:

[0017] Where s(t) represents the target position of the servo motor at time t. to These are coefficients to be determined; The undetermined coefficients are determined by matching the boundary conditions at the start and end points of the motion process. These boundary conditions include position, velocity, acceleration, and jerk. The following constraints are set to be satisfied at the start time t=0 and end time t=T: Position: s(0)=0, s(T)=S_target; Velocity: v(0)=0, v(T)=0; Acceleration: a(0)=0, a(T)=0; Jerk: j(0)=0, j(T)=0; By solving the system of eight equations, the eight coefficients are determined. to This generates a smooth and continuous motion trajectory. Then, rigid body kinematics is used to solve the inverse kinematics of the sheet metal posture adjustment device to obtain the change curves corresponding to each joint.

[0018] The present invention employs a velocity curve planning and control strategy based on a seventh-order polynomial algorithm in the pose adjustment process described in step S3. By performing high-order smoothing optimization on the motion trajectory of the actuator, it ensures that the system vibration and impact are effectively suppressed while meeting the requirements of high-speed response.

[0019] The beneficial effects of this invention are: 1. This invention utilizes a line scan camera to scan the outline of the transmitted sheet metal in real time, combined with a movable and rotatable alignment platform to achieve precise alignment and angle correction. It enables real-time scanning and calculation of pose deviations during continuous sheet metal transport, and employs a dual 3-PRR parallel alignment platform for rapid adaptive adjustment, improving alignment efficiency, reducing adjustment time, and enhancing alignment accuracy. This meets the precise alignment requirements of sheets of different sizes, improves product quality and production efficiency, and solves the problem of position and angle deviations when loading sheet metal at the beginning of a stamping production line. It is particularly suitable for unmanned production and high-speed continuous transport scenarios in modern smart factories.

[0020] 2. This invention uses two or more high-speed linear scan cameras to scan the edge contour of the sheet metal in real time, ensuring that the sheet metal can be detected while in motion, thus improving detection accuracy. Combined with a fast-response centering platform, the overall centering cycle time is reduced by more than 50%, significantly improving production efficiency. 3. This invention can automatically identify different specifications of sheet metal and quickly complete parameter switching, reducing the changeover time from the traditional 10-15 minutes to less than 30 seconds, greatly improving the flexibility of the production line.

[0021] 4. By installing vacuum adsorption units at the bottom of the transition belt and centering belt, the sheet material is reliably adsorbed at the position of the transition conveyor or the centering platform, ensuring accurate and reliable material positioning, preventing slippage, and achieving high centering efficiency to meet the needs of real-time high-speed transmission.

[0022] 5. The method of the present invention, through a high-precision vision inspection system combined with a motion compensation algorithm, can achieve a high positioning accuracy of ±1mm through a centering platform, accurately and quickly complete the sheet metal pose adjustment, realize real-time scanning and calculation of pose deviation during continuous sheet metal transmission, improve centering efficiency, reduce centering adjustment time, improve centering accuracy, enhance product quality and production efficiency, has a high level of automation, effectively avoids errors caused by manual intervention, and improves product quality and production efficiency.

[0023] 6. The present invention employs a velocity curve planning and control strategy based on a seventh-order polynomial algorithm in the pose adjustment process described in step S3. By performing high-order smoothing optimization on the motion trajectory of the actuator, it ensures that the system vibration and impact are effectively suppressed while meeting the requirements of high-speed response. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 A top-view structural diagram; Figure 3 This is a flowchart of the steps of the present invention; In the diagram, 1 is the transition belt, 2 is the sheet metal, 3 is the vision inspection device, 4 is the centering platform, 5 is the vacuum adsorption unit, and 6 is the centering belt. Detailed Implementation

[0026] To make the objectives, features, and advantages of this invention clearer and easier to understand, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0027] Example 1 Combination Figures 1-3A sheet metal alignment system for an automotive stamping line includes a sheet metal transition conveyor, an alignment platform 4, a vision inspection device 3, and a controller. The alignment platform 4 is equipped with a sheet metal posture adjustment device or alignment mechanism. The controller is electrically connected to the sheet metal transition conveyor, the alignment platform 4, and the vision inspection device 3. The alignment platform 4 is arranged adjacent to the sheet metal transition conveyor. The vision inspection device 3 is located above the sheet metal transition conveyor and the alignment platform 4. The alignment platform 4 is equipped with a platform transmission mechanism that transports the sheet metal 2 to the alignment station of the alignment platform 4. The vision inspection device 3 includes a line scan camera, such as a high frame rate line scan camera, and is equipped with an autofocus module and a polarizing filter. The line scan camera scans the edge contour of the sheet metal in real time to ensure that the sheet metal 2 can be detected while in motion. The controller calculates the inverse kinematics of the alignment platform 4 in real time based on the detection results obtained by the vision inspection device 3, and completes the sheet metal posture adjustment through the movement of the alignment platform 4.

[0028] The sheet metal transition conveyor uses a belt conveyor mechanism, which includes a transition belt 1 and a belt conveyor mechanism that drives the transition belt 1 to move at a constant speed. The belt conveyor mechanism uses an electric roller conveyor line, with anti-slip stripes embedded on the belt surface. The belt conveying speed is adjustable, and it is equipped with an incremental encoder to record the belt position. The transition belt 1 moves in a stepping manner, such as by using a stepper motor to drive it and having the encoder control the position of the transition belt 1 in real time, ensuring that it moves strictly according to the step distance.

[0029] The centering platform 4 is equipped with a platform transmission mechanism, which includes a centering belt 6. The centering belt 6 transports the sheet material to the centering station of the centering platform 4. A vacuum adsorption unit 5 is provided below the belt to provide negative pressure adsorption for centering the sheet material.

[0030] The system includes two or more line scan cameras, which are arranged laterally along the belt, i.e., perpendicular to the belt's direction of movement. These cameras are sequentially mounted transversely above the conveyor belt and the centering belt 6 to scan the edge contour of the sheet metal in real time, ensuring that the sheet metal can be detected while in motion and improving detection accuracy. Furthermore, a strip light source is provided, with brightness adjustable according to specific site conditions. The line scan cameras are mounted on a bracket equipped with a three-dimensional adjustment mechanism in the X / Y / Z directions.

[0031] The controller includes an image processing unit, which receives sheet metal edge contour detection information sent by a linear scan camera and extracts the sheet metal position and angle deviation using the sheet metal edge contour detection information and a matching algorithm.

[0032] The centering platform 4 (3) includes an X / Y linear motor module. The centering platform 4 adopts a dual 3-PRR parallel mechanism. Both the single 3-PRR mechanism and the dual 3-PRR mechanism have X / Y translation and θ rotation degrees of freedom to realize dual-material working mode and single-material working mode.

[0033] Each 3-PRR mechanism consists of three parallel PRR (translation-rotation-rotation) branches, possessing X / Y translational and θ rotational degrees of freedom. The controller calculates the inverse kinematics of the 3-PRR mechanism in real time based on the detection results from the line scan camera, and drives the centering platform 4 to move and rotate via servo motors to complete the sheet metal orientation adjustment. The platform 4 is equipped with a vacuum suction hole array to provide negative pressure, ensuring that the material does not slip.

[0034] The dual-material working mode involves two small plates entering two separate 3-PRR mechanisms, with each plate independently adjusting its position and orientation. The single-material working mode involves a single large plate spanning two 3-PRR mechanisms, achieving overall position and orientation correction and adjustment through coordinated motion.

[0035] Example 2 Combination Figures 1-3 A method for centering the first sheet metal in an automotive stamping line, employing the aforementioned automotive stamping line first sheet metal centering system, involves edge extraction and pose error calculation via a controller, calculation of joint motion compensation using a rigid body kinematics model, and adjustment of the sheet metal pose by driving the joints of the centering platform 4 via a motor. The method includes the following steps: S01: The vision inspection device 3 continuously acquires images of the sheet metal edge and transmits the images back to the controller; Before S01, the system initialization and configuration phase needs to be carried out, including the establishment and calibration of the equipment coordinate system, the pre-storage of the geometric parameters and standard position information of various standard plates into the control system database, and the completion of the basic parameter configuration and system readiness preparation of the vision inspection unit and the execution unit. S02: The controller processes image information to obtain the actual pose of the sheet metal, compares it with the standard pose, and obtains the position deviation and angle deviation. In this stage, dynamic visual detection and data processing of the sheet metal edge contour are realized, including continuous real-time image acquisition of the running sheet metal edge contour through a high frame rate linear array camera. Based on the acquired image sequence and associated position sensing information, the image processing and pose calculation module in the controller accurately calculates the linear offset in the X and Y directions and the rotation angle deviation between the current actual position of the sheet metal and the preset standard position. In S02, the controller pre-stores a coordinate transformation matrix determined by hand-eye calibration. The coordinate transformation matrix describes the coordinate transformation relationship between the image pixel coordinate system and the static coordinate system. When using a single sheet, the static coordinate system is an absolute rectangular coordinate system pre-calibrated and fixed to the center of the centering platform 4. Its XY plane is located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward. When using two sheets, it includes two independent static coordinate systems. The two static coordinate systems are absolute rectangular coordinate systems pre-calibrated to the centers of the left and right surfaces of the centering platform 4. Their XY planes are both located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward.

[0036] The controller receives the sheet metal edge image scanned by the linear scan camera and reconstructs the sheet metal contour. It then obtains the coordinates of the sheet metal contour points in the static coordinate system through a coordinate transformation matrix and calculates the deviation between the actual position and the standard position of the sheet metal. This pose deviation includes the linear deviation of the sheet metal in the X direction within the static coordinate system. Linear deviation in the X and Y directions Y and rotation angle deviation θ; where, X = X_actual - X_ref, Y = Y_actual - Y_ref θ = θ_actual - θ_ref; (X_actual, Y_actual, θ_actual) is the actual pose of the sheet metal calculated by visual inspection, (X_ref, Y_ref, θ_ref) is the pre-stored standard pose of the sheet metal, and the rotation angle deviation θ is positive in the counterclockwise direction around the Z-axis of the static coordinate system; By fusing continuous sequence scan line data acquired by a linear array camera with high-precision position information fed back in real time by the encoder of the belt conveyor, the local edge image data during the sheet metal movement process is temporally aligned and spatially correlated. Then, the boundary point cloud model of the complete outline of the sheet metal is generated through image stitching and reconstruction technology. Based on the synthesized global image information, a DP-based image registration algorithm is used to perform high-precision matching and comparison between the real-time acquired sheet metal outline and the pre-stored standard outline template, thereby calculating the precise pose deviation of the sheet metal in the planar coordinate system.

[0037] S03: Plan the adjustment trajectory of the centering platform 4, generate a smooth motion curve, and solve the required displacement of each joint of the centering platform 4 based on rigid body kinematics. S04: The controller drives the centering platform 4 to complete the multi-axis linkage position adjustment. The sheet metal moves and rotates rigidly with the centering platform 4 to reach the target posture. After the sheet metal posture is adjusted to the target state, the centering platform 4 enters the posture locking mode, which keeps the corrected sheet metal stably in the predetermined posture for a set period of time to ensure that the actuators of subsequent processes can reliably and without damage complete the sheet metal gripping and transfer operations.

[0038] S05: Once the sheet material is removed, the centering platform 4 automatically resets, awaiting the next adjustment.

[0039] In S02, the controller pre-stores a coordinate transformation matrix determined by hand-eye calibration. This matrix describes the coordinate transformation relationship between the image pixel coordinate system and the static coordinate system. For single-sheet material, the static coordinate system is a pre-calibrated absolute rectangular coordinate system fixed to the center of the centering platform 4. Its XY plane lies within the material's movement plane, with the x-axis perpendicular to the material flow direction, the Y-axis coinciding with the material flow direction, and the Z-axis vertically upwards perpendicular to the XY plane. For double-sheet material, two independent static coordinate systems are included. These two static coordinate systems are pre-calibrated absolute rectangular coordinate systems at the centers of the left and right surfaces of the centering platform 4. Their XY planes both lie within the material's movement plane, with the x-axis perpendicular to the material flow direction, the Y-axis coinciding with the material flow direction, and the Z-axis vertically upwards perpendicular to the XY plane.

[0040] The controller receives the sheet metal edge image scanned by the linear scan camera and reconstructs the sheet metal contour. It obtains the coordinates of the sheet metal contour points in the static coordinate system through a coordinate transformation matrix and calculates the pose deviation between the actual position and the standard position of the sheet metal. The pose deviation includes the linear deviation of the sheet metal in the X direction within the static coordinate system. Linear deviation in the X and Y directions Y and rotation angle deviation θ; where, X = X_actual - X_ref, Y = Y_actual - Y_ref θ = θ_actual-θ_ref; where X_actual, Y_actual, and θ_actual are the actual poses of the sheet metal obtained through visual detection, and X_ref, Y_ref, and θ_ref are the pre-stored standard sheet metal poses. The rotation angle deviation θ is positive in the counterclockwise direction around the Z-axis of the static coordinate system.

[0041] In step S03, when using double plates, based on the left and right pose deviations obtained in step S02, the controller plans the motion trajectory of the left and right surfaces of the centering platform 4 from the current pose to the target pose using a seventh-order polynomial, thereby obtaining a smooth motion curve where position, velocity, acceleration, and jerk are all continuous and the boundary values ​​are zero. Subsequently, based on the kinematic model of the centering platform 4, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time. When processing single-sheet material, a set of pose deviations is obtained according to step S02. The controller plans the motion trajectory of the entire platform 4 from the current pose to the target pose based on a seventh-order polynomial, thereby obtaining a smooth motion curve in which position, velocity, acceleration, and jerk are all continuous and the boundary value is zero. Subsequently, based on the kinematic model of the platform 4, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time.

[0042] To ensure the smoothness and accuracy of the centering platform 4's motion and to suppress vibration, the controller employs a seventh-order polynomial programming method for the motion trajectory of the entire platform 4 from its current pose to the target pose. The functional expression of the motion trajectory is as follows:

[0043] Where s(t) represents the target position of the servo motor at time t. to These are coefficients to be determined; The undetermined coefficients are determined by matching the boundary conditions at the start and end points of the motion process. These boundary conditions include position, velocity, acceleration, and jerk. The following constraints are set to be satisfied at the start time t=0 and end time t=T: Position: s(0)=0, s(T)=S_target; Velocity: v(0)=0, v(T)=0; Acceleration: a(0)=0, a(T)=0; Jerk: j(0)=0, j(T)=0; By solving the system of eight equations, the eight coefficients are uniquely determined. to This generates a smooth and continuous motion trajectory. Then, rigid body kinematics is used to solve the inverse kinematics of the sheet metal posture adjustment device to obtain the change curves corresponding to each joint.

[0044] The present invention employs a velocity curve planning and control strategy based on a seventh-order polynomial algorithm in the pose adjustment process described in step S3. By performing high-order smoothing optimization on the motion trajectory of the actuator, it ensures that the system vibration and impact are effectively suppressed while meeting the requirements of high-speed response.

[0045] The above description represents preferred embodiments of the present invention. The specific embodiments are provided solely for a better understanding of the invention's concept. Those skilled in the art can make various improvements or equivalent substitutions based on the principles of the present invention, and these improvements or equivalent substitutions are also considered to fall within the scope of protection of the present invention.

Claims

1. A sheet metal alignment system for an automotive stamping line, comprising a sheet metal transition conveyor, an alignment platform, a vision inspection device, and a controller, wherein the controller is electrically connected to the sheet metal transition conveyor, the alignment platform, and the vision inspection device, characterized in that... The centering platform is equipped with a sheet metal posture adjustment device. The centering platform and the sheet metal transition conveying device are arranged adjacent to each other. A vision inspection device is installed on the upper part between the sheet metal transition conveying device and the centering platform. The centering platform is equipped with a platform transmission mechanism, which transports the sheet metal to the centering station of the centering platform. The vision inspection device includes a line scan camera, which scans the edge contour of the sheet metal in real time. The image processing unit of the controller receives the edge contour detection information of the sheet metal sent by the line scan camera, extracts the position and angle deviation of the sheet metal through a matching algorithm, and calculates the inverse kinematics solution of the centering platform in real time. The movement of the centering platform completes the sheet metal posture adjustment.

2. The first sheet metal alignment system for an automotive stamping line according to claim 1, characterized in that, The centering platform includes an X / Y linear motor module and adopts a dual 3-PRR parallel mechanism. Both the single 3-PRR mechanism and the dual 3-PRR mechanism have X / Y translational and θ rotational degrees of freedom to realize dual-material working mode and single-material working mode.

3. The first sheet metal alignment system for an automotive stamping line according to claim 2, characterized in that, The dual-material working mode involves two small plates entering two separate 3-PRR mechanisms, with each small plate independently adjusting its position and orientation. The single-material working mode involves a single large plate spanning two 3-PRR mechanisms, achieving overall position and orientation correction and adjustment through coordinated motion.

4. The first sheet metal alignment system for an automotive stamping line according to claim 1, characterized in that, The sheet material transition conveying device adopts a belt conveyor mechanism, which includes a transition belt and a belt conveyor mechanism that drives the transition belt to move at a constant speed. The centering platform is equipped with a platform transmission mechanism, which includes a centering belt to transport the sheet material to the centering station of the centering platform.

5. The first sheet metal alignment system for an automotive stamping line according to claim 4, characterized in that, The transition belt and centering belt are equipped with vacuum adsorption units at their lower parts, which reliably adsorb the sheet material at the position of the transition conveyor or the centering platform.

6. The first sheet metal alignment system for an automotive stamping line according to claim 4, characterized in that, The linear array camera is provided in two or more configurations, which are arranged laterally along the belt and sequentially installed above the transition belt and the centering belt.

7. A method for centering the first sheet metal in an automotive stamping line, characterized in that, The automotive stamping line first sheet alignment system according to claim 1 includes the following steps: S01: The vision inspection device continuously acquires images of the sheet metal edges and transmits the images back to the controller; S02: The controller processes the image information to obtain the actual pose of the sheet metal, compares it with the standard pose, and obtains the position deviation and angle deviation. S03: Plan the adjustment trajectory of the centering platform, generate a smooth motion curve, and solve the required displacement of each joint of the centering platform based on rigid body kinematics. S04: The controller drives the centering platform to complete multi-axis linkage position adjustment. The sheet metal moves and rotates rigidly with the centering platform to achieve the target posture. S05: Once the sheet material is removed, the centering platform automatically resets, awaiting the next adjustment.

8. The method for centering the first sheet metal in an automotive stamping line according to claim 7, characterized in that, in Before S01, the system initialization phase is carried out, including the establishment and calibration of the equipment coordinate system, the pre-storage of the geometric parameters and standard position information of various standard plates into the control system database, and the completion of the basic parameter configuration and system readiness preparation of the vision inspection unit and the execution unit.

9. The method for centering the first sheet metal in an automotive stamping line according to claim 7, characterized in that, in In S02, the controller pre-stores a coordinate transformation matrix determined by hand-eye calibration. The coordinate transformation matrix describes the coordinate transformation relationship between the image pixel coordinate system and the static coordinate system. When using a single sheet, the static coordinate system is a pre-calibrated absolute rectangular coordinate system fixed to the center of the centering platform. Its XY plane is located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward. When using two sheets, it includes two independent static coordinate systems. The two static coordinate systems are pre-calibrated absolute rectangular coordinate systems at the centers of the left and right surfaces of the centering platform. Their XY planes are both located in the sheet movement plane, the X-axis is perpendicular to the material flow direction, the Y-axis coincides with the material flow direction, and the Z-axis is perpendicular to the XY plane and vertically upward. The controller receives the sheet metal edge image scanned by the linear scan camera and reconstructs the sheet metal contour. It then obtains the coordinates of the sheet metal contour points in the static coordinate system through a coordinate transformation matrix and calculates the deviation between the actual position and the standard position of the sheet metal. This pose deviation includes the linear deviation of the sheet metal in the X direction within the static coordinate system. Linear deviation in the X and Y directions Y and rotation angle deviation θ; where, X = X_actual - X_ref, Y = Y_actual - Y_ref θ = θ_actual - θ_ref; (X_actual, Y_actual, θ_actual) is the actual pose of the sheet metal calculated by visual inspection, (X_ref, Y_ref, θ_ref) is the pre-stored standard pose of the sheet metal, and the rotation angle deviation θ is positive in the counterclockwise direction around the Z-axis of the static coordinate system; By fusing continuous scan line data acquired by a linear array camera with high-precision position information fed back in real time by the encoder of the belt conveyor, the local edge image data during the sheet metal movement process is temporally aligned and spatially correlated. Then, a complete outline model of the sheet metal is generated through image stitching and reconstruction technology. Based on the synthesized global image information, a DP-based image registration algorithm is used to perform high-precision matching and comparison between the real-time acquired sheet metal outline and the pre-stored standard outline template, thereby calculating the precise pose deviation of the sheet metal in the planar coordinate system.

10. The method for centering the first sheet metal in an automotive stamping line according to claim 9, characterized in that, In step S03, when using double plates, based on the left and right pose deviations obtained in step S02, the controller plans the motion trajectory of the left and right platforms of the centering platform from the current pose to the target pose using a seventh-order polynomial, thereby obtaining a smooth motion curve where the position, velocity, acceleration, and jerk are all continuous and the boundary values ​​are zero. Subsequently, based on the kinematic model of the centering platform, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time. When processing single-sheet material, a set of pose deviations is obtained according to step S02. The controller plans the motion trajectory of the entire platform from the current pose to the target pose based on a seventh-order polynomial, thereby obtaining a smooth motion curve in which position, velocity, acceleration, and jerk are all continuous and the boundary value is zero. Subsequently, based on the kinematic model of the platform, the controller solves for the displacement required from the desired pose to each driven joint, and obtains the motion curve of each joint over time. To ensure the stability and accuracy of the alignment platform's movement and to suppress vibration, the controller employs a seventh-order polynomial programming method for the motion trajectory of the entire alignment platform surface from its current pose to the target pose. The functional expression of the motion trajectory is as follows: Where s(t) represents the target position of the servo motor at time t. to These are coefficients to be determined; The undetermined coefficients are determined by matching the boundary conditions at the start and end points of the motion process. These boundary conditions include position, velocity, acceleration, and jerk. The following constraints are set to be satisfied at the start time t=0 and end time t=T: Position: s(0)=0, s(T)=S_target; Velocity: v(0)=0, v(T)=0; Acceleration: a(0)=0, a(T)=0; Jerk: j(0)=0, j(T)=0; By solving the system of eight equations, the eight coefficients are determined. to A smooth and continuous motion trajectory is generated, and then the inverse kinematics of the sheet metal pose adjustment device is solved using rigid body kinematics to obtain the change curves corresponding to each joint.

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