A method and system for measuring the double-sided profile of medium-thick stainless steel plates

Abstract

The present invention belongs to the technical field of strip shape monitoring and visual analysis, and discloses a method and system for measuring the double-sided contour of medium-thick stainless steel plates. Step S1: Complete the calibration of the double linear array cameras to obtain the images of the upper and lower surfaces of the medium-thick plate; Step S2: Perform binocular stereo vision three-dimensional reconstruction to generate a point cloud map and convert it to be displayed in the same coordinate system; Step S3: Eliminate the lateral rotation and offset according to the fitting of the center lines and plane fitting of the point clouds on the upper and lower surfaces of the medium-thick plate; Step S4: Compare the geometric relationships between the point clouds on the upper and lower surfaces to quantify the local vibration and thickness change, correct the vibration error, and obtain the thickness of the medium-thick plate; Step S5: Extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtain the shear line position based on the detection of the width and edge linearity of the medium-thick plate. By adopting the technical solution of the present invention, the overall contour, overall thickness distribution and accurate shear position of the medium-thick plate can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of plate shape monitoring and visual analysis, and particularly relates to a method and system for measuring the double-sided profile of medium-thick stainless steel plates. Background Art

[0002] Currently, during the production process of medium-thick plates, the rough billet undergoes multiple repeated rollings, temperature fluctuations, strip length, rolling force, etc. all affect the plate shape, and may also cause unevenness in the thickness of the medium-thick plate at different positions. Due to the existence of these objective factors, after rolling, medium-thick plates generally have plate shape defects. Such as head and tail deformations in the length direction and sickle-shaped deformations in the width direction. After rolling to the standard thickness, according to the standard size width of the medium-thick plate, side shearing is performed on the medium-thick plate, and then operations such as cutting the head, cutting the tail, and sizing are carried out, which are important processes for producing finished medium-thick plates that meet the specification requirements.

[0003] Currently, after side shearing of medium-thick plates, the irregular shapes of the head and tail during shearing still require manual visual judgment of the cutting head and cutting tail positions, which is prone to phenomena such as under-shearing and over-shearing. The thickness of medium-thick plates is usually measured by a laser thickness gauge. Although this instrument has high measurement accuracy and can measure the thickness of the steel plate in real time, the laser thickness gauge has poor adaptability to medium-thick plates with different materials and surface characteristics. In addition, a high-temperature environment will also cause scattering or refraction of the laser beam, affecting the measurement accuracy, and a single laser thickness gauge cannot comprehensively obtain the overall thickness distribution of the medium-thick plate.

[0004] In terms of visual measurement, due to the complex production site environment, there are adverse factors such as high temperature, dust, and noise, which affect the stability and measurement accuracy of the optical sensor for image acquisition and the measurement system. At the same time, the friction between the medium-thick plate and the roller table during transportation may cause unpredictable rotation and offset, accompanied by up and down vibrations, further increasing the uncertainty of the movement trajectory of the medium-thick plate, making it impossible to accurately obtain the contour information of the medium-thick plate, affecting the overall thickness statistics and shear position determination of the medium-thick plate. Therefore, in order to obtain the overall contour, overall thickness distribution of the medium-thick plate, and determine the shear position, it is of important application value to invent a detection method for medium-thick plates with high measurement accuracy and strong adaptability. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a method and system for measuring the double-sided profile of medium-thick stainless steel plates. Multiple camera groups are used to simultaneously acquire images on the upper and lower sides of the medium-thick plate, perform binocular stereo vision three-dimensional reconstruction, obtain the three-dimensional data of the upper and lower surface contours of the medium-thick plate, correct the lateral offset and up and down vibration errors of the medium-thick plate, and obtain the accurate information of the surface contour of the medium-thick plate and the overall thickness distribution of the medium-thick plate. Based on the detection of the width consistency and edge linearity of the medium-thick plate, the shear positions of different-shaped plate heads are accurately located, thereby quickly determining the shear position and shear length.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for measuring the double-sided profile of medium-thick stainless steel plates, the method comprising:

[0008] S1. Complete the calibration of the double-line array camera to obtain the images of the upper and lower surfaces of the medium-thick stainless steel plate;

[0009] S2. Perform binocular stereo vision three-dimensional reconstruction on the images of the upper and lower surfaces of the medium-thick stainless steel plate to generate a point cloud map, and convert it to be displayed in the same coordinate system;

[0010] S3. Eliminate the lateral rotation and offset according to the center line fitting and plane fitting of the point clouds on the upper and lower surfaces of the medium-thick plate;

[0011] S4. Compare the geometric relationships between the point clouds on the upper and lower surfaces to quantify the local vibration and thickness change, correct the vibration error, and obtain the thickness of the medium-thick plate;

[0012] S5. Extract the edge point set from the point cloud map to obtain the overall profile of the medium-thick plate, and detect the position of the shearing line based on the width of the medium-thick plate and the linearity of the edge.

[0013] Preferably, in the S1, the calibration of the double-line array camera includes:

[0014] Select a transparent calibration plate, and through the stable movement of the calibration plate, scan and splice row by row to generate a complete two-dimensional image;

[0015] Extract the feature points in the two-dimensional image, combine the known physical dimensions of the calibration plate, and optimize and calculate the internal and external parameters of the camera through the calibration algorithm;

[0016] Calibrate the geometric relationship of the double-line array camera.

[0017] Preferably, in the S2, the binocular stereo vision three-dimensional reconstruction of the images of the upper and lower surfaces of the medium-thick stainless steel plate to generate a point cloud map includes:

[0018] After obtaining the images of the upper and lower surfaces of the medium-thick stainless steel plate, perform stereo correction on the images according to the calibration parameters, and map the images to a coplanar plane to eliminate the vertical parallax;

[0019] Use the stereo matching algorithm to calculate the disparity map, and generate depth information through the position difference of the corresponding pixel points in the two images;

[0020] According to the disparity map and the internal and external parameters of the camera, project the pixel points into the three-dimensional space to generate the point cloud data of the surface of the medium-thick plate.

[0021] Preferably, in the S3, eliminating the lateral rotation and offset according to the center line fitting and plane fitting of the point clouds on the upper and lower surfaces of the medium-thick plate includes:

[0022] Low-density points or abnormal distance points are detected through statistical characteristic analysis. Interference points are removed from the 3D reconstructed point cloud image by combining local curvature calculation method and normal vector consistency analysis, and vacant areas are repaired using nearest neighbor interpolation.

[0023] Fit the point cloud planes of the upper and lower surfaces, calculate the center lines respectively, and determine the offset and rotation amount through the relationship between the center lines, and construct the rigid body transformation matrix for correction;

[0024] Among them, the point cloud plane fitting of the upper and lower surfaces includes:

[0025] The RANSAC algorithm is used to perform plane fitting on the upper and lower surfaces of the medium and thick plate. The fitting formula is:

[0026] ;

[0027] in, is the fitting parameter, is the coordinate of the point in the 3D point cloud;

[0028] Calculating the centerline includes:

[0029] Select parallel cross-section point clouds with fixed intervals on the upper and lower surfaces respectively, and calculate the geometric center of each cross-section:

[0030] ;

[0031] in, The geometric center point of the section is the coordinate average of all point clouds within a certain slice section, i.e., the centroid. The number of point clouds in the current section, Index variable, indicating that the number currently being accumulated is points, ranging from 1 to , is the point cloud coordinate on the cross section;

[0032] Connect all the cross-section center points to obtain the center lines of the upper and lower surfaces;

[0033] Determining offset and rotation based on the relationship between centerlines includes:

[0034] ;

[0035] in, and are the center point coordinates of the upper and lower surfaces respectively;

[0036] Constructing a rigid body transformation matrix for correction includes:

[0037] Based on the offset and rotation calculated above, construct the rigid body transformation matrix:

[0038] ;

[0039] Among them, is the rotation matrix;

[0040] Perform a rigid body transformation on the point clouds of the upper and lower surfaces:

[0041] ;

[0042] Among them, is the original point cloud, is the corrected point cloud.

[0043] Preferably, in S4, compare the geometric relationship between the point clouds of the upper and lower surfaces to quantify local vibrations and thickness changes, correct the vibration error, and obtain the thickness of the medium-thick plate, including:

[0044] Use frequency domain analysis to extract the vibration error components, calculate the offset vector, and adjust along the normal vector direction;

[0045] After eliminating the vibration error, divide the point clouds of the upper and lower surfaces of the medium-thick plate into several small regions, calculate the average thickness of the points in each region, and finally obtain the thickness distribution and overall thickness statistics of the medium-thick plate.

[0046] Preferably, using frequency domain analysis to extract the vibration error components, calculate the offset vector, and adjust along the normal vector direction includes:

[0047] Adopt nearest neighbor point matching to make each point in the point clouds of the upper and lower surfaces find the corresponding relationship, and calculate the vertical distance between each pair of matching points on the upper and lower surfaces:

[0048] ;

[0049] Among them, is the projection distance of the point cloud on the normal vector, and are the corresponding points on the upper and lower surfaces respectively, is the global normal vector;

[0050] For perform a fast Fourier transform to extract the main frequency distribution:

[0051] ;

[0052] Among them, is the frequency component of the vibration signal obtained by the fast Fourier transform, is the index of the discrete data points, is the total number of data points in the input signal, is the projection distance of the point cloud on the normal vector, is the complex exponential basis function of Fourier transform;

[0053] According to the main frequency distribution, set the vibration frequency range as , and use a band-pass filter to extract the vibration signal:

[0054] ;

[0055] Among them, is the vibration error signal after frequency-domain filtering, are the upper and lower limits of the vibration frequency range, is the frequency component of the vibration signal, is the complex exponential basis function of inverse Fourier transform;

[0056] Use frequency-domain analysis to extract the vibration error component , which represents the vertical vibration between the upper and lower surfaces of the medium-thick plate, and calculate the offset vector , and adjust it along the normal vector direction;

[0057] ;

[0058] For the original coordinates of each pair of point clouds, adjust the point clouds according to the vibration component:

[0059] ;

[0060] Among them, is the corrected point coordinate, is the original point coordinate of the upper surface before correction, is the corresponding original point coordinate of the lower surface before correction, is the offset vector;

[0061] By correcting the error between the corresponding point clouds on the upper and lower surfaces of the medium-thick plate, the influence of the medium-thick plate vibration is eliminated.

[0062] Preferably, after eliminating the vibration error, the point clouds on the upper and lower surfaces of the medium-thick plate are divided into several small regions, and the average thickness of the points in each region is calculated. Finally, the thickness distribution and overall thickness statistics of the medium-thick plate are obtained, including:

[0063] For each grid region, calculate the average thickness of all point pairs in the region:

[0064] ;

[0065] Among them, is the number of points in the grid;

[0066] Use the grid-averaged thickness method to divide the point clouds on the upper and lower surfaces into small regions, calculate the average thickness for each grid, and finally generate the regional thickness distribution map of the medium-thick plate;

[0067] According to the regional thickness distribution map of the medium-thick plate, identify the locally varying thickness of the medium-thick plate, and finally obtain the overall thickness of the medium-thick plate.

[0068] Preferably, in S5, to extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and the detection of the shearing line position based on the width and edge linearity of the medium-thick plate includes:

[0069] Obtain the width of the medium-thick plate through the specification model parameters of the medium-thick plate ;

[0070] According to the width of the medium-thick plate , calculate the corresponding width point by point for the head and tail regions of the medium-thick plate contour, and construct a width sequence And based on the change of the width, preliminarily determine the cutting position, and the corresponding width sequence is ;

[0071] Judge whether the width sequence within the region is consistent. If the width consistency condition is met, that is, the width fluctuation is within the specified threshold, it is considered that the region is suitable for cutting. Detect the continuous sub-regions of the width sequence , and set the starting index as . If the preset condition is met, it is considered that the width of the region is consistent; among them, the preset condition is:

[0072] ;

[0073] Among them, is the length of the detection range, is the width consistency threshold;

[0074] Within the region where the width consistency is satisfied, further extract the left and right edge points of each row, and judge whether the edge meets the preset linearity requirement through linear fitting to calculate the fitting residual, that is, compare the maximum value of the fitting residual with the set threshold to accurately judge whether the left and right edges are straight, so as to further lock the optimal cutting position and ensure that the cut edge is flat and smooth.

[0075] The present invention also provides a double-sided contour measurement system for stainless steel medium-thick plates. The system is used for any one of the methods described above. The system includes: an image acquisition unit, a three-dimensional reconstruction unit, a motion correction unit, a thickness measurement and error correction unit, and a contour detection and shearing positioning unit;

[0076] The image acquisition unit is used to complete the calibration of the double-line array camera to obtain the upper and lower surface images of the stainless steel medium-thick plate;

[0077] The three-dimensional reconstruction unit is used to perform binocular stereo vision three-dimensional reconstruction on the upper and lower surface images of the stainless steel medium-thick plate to generate a point cloud map and display it in the same coordinate system;

[0078] The motion correction unit is configured to eliminate lateral rotation and offset according to the fitting of the center line of the point clouds on the upper and lower surfaces of the medium-thick plate and plane fitting.

[0079] The thickness measurement and error correction unit is configured to compare the geometric relationship between the point clouds on the upper and lower surfaces to quantify local vibrations and thickness changes, correct vibration errors, and obtain the thickness of the medium-thick plate.

[0080] The contour detection and shearing positioning unit is configured to extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and detect the shearing line position based on the width of the medium-thick plate and edge linearity.

[0081] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0082] The present invention performs stereo vision three-dimensional reconstruction on the collected images of the upper and lower surfaces of the medium-thick plate, eliminates interference points, eliminates lateral rotation and offset by fitting the center lines of the upper and lower surface point clouds and plane fitting, compares the geometric relationship between the upper and lower surface point clouds to quantify local vibrations and thickness changes, corrects vibration errors, obtains the overall thickness of the medium-thick plate, extracts the edge point set from the point cloud map to obtain the edge contour of the medium-thick plate, and detects the shearing line position based on the width of the medium-thick plate and edge linearity. The present invention can obtain the overall contour, overall thickness distribution and accurate shearing position of the medium-thick plate, provide comprehensive and accurate data for the production quality of medium-thick plates in the metallurgical industry, promote the optimization of production processes and the improvement of the production quality of medium-thick plates, and has important theoretical significance and great practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions of the present invention, the accompanying drawings required for use in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0084] Figure 1 It is a schematic flow chart of the double-sided contour measurement method for stainless steel medium-thick plates in the embodiments of the present invention;

[0085] Figure 2 It is another schematic flow chart of the double-sided contour measurement method for stainless steel medium-thick plates in the embodiments of the present invention;

[0086] Figure 3 It is a schematic diagram of the actual measurement of medium-thick plates on the production line in the embodiments of the present invention;

[0087] Figure 4 It is a top view schematic diagram of the actual measurement of medium-thick plates on the production line.

[0088] In the figure: 1. Profiler, 2. Metal protection box, 3. Linear light source, 4. Automatic cleaning device, 5. Synchronous trigger, 6. Medium-thick plate to be measured, 7. Roller table. Detailed implementation mode

[0089] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0090] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes.

[0091] Embodiment 1

[0092] As Figures 1-4 shown, the double-sided profile shape measurement method and system for stainless steel medium-thick plates mainly include dual linear array camera calibration, binocular stereo vision three-dimensional reconstruction, eliminating the motion deviation of the medium-thick plate, and adaptively determining the shearing position. This process includes the following steps:

[0093] The structured light scanning device is composed of 4 high-precision industrial linear array cameras. Two linear array cameras are integrated and placed side by side to form a profiler. One profiler is installed above the roller table 7 and arranged parallel to the roller table 7. The total field of view of the two cameras completely covers the transverse width of the medium-thick plate. At the same time, it is ensured that there is a partial overlapping area in the images collected by the two cameras. A dust-proof cover is added to the profiler to avoid dust accumulation. Another profiler is installed below the roller table 7 and symmetrically arranged with the upper surface camera, and the symmetry center is the surface of the roller table 7. A closed metal protection box 2 is used, and a transparent high-temperature resistant glass window is installed inside for dust prevention, shock prevention, and anti-oil pollution, and an automatic cleaning device 4 is equipped. A uniformly scattered linear light source 3 is used on the upper surface of the roller table 7, and a high-power linear light source 3 is used on the lower surface to ensure clear image acquisition.

[0094] A synchronous trigger 5 is installed at the position of the roller table 7 corresponding to the profiler to record the real-time speed and position of the medium-thick plate movement and provide a synchronous trigger signal. Ensure that the upper and lower cameras simultaneously collect images of the same area.

[0095] The present invention discloses a double-sided profile measurement method for stainless steel medium-thick plates, and the method includes:

[0096] S1. Complete the calibration of the dual linear array cameras to obtain the upper and lower surface images of the stainless steel medium-thick plate;

[0097] S2. Perform binocular stereo vision three-dimensional reconstruction on the upper and lower surface images of the medium-thick stainless steel plate to generate a point cloud map, and convert it for display in the same coordinate system;

[0098] S3. Eliminate lateral rotation and offset according to the fitting of the center lines of the point clouds on the upper and lower surfaces of the medium-thick plate and plane fitting;

[0099] S4. Compare the geometric relationships between the point clouds on the upper and lower surfaces to quantify local vibrations and thickness changes, correct vibration errors, and obtain the thickness of the medium-thick plate;

[0100] S5. Extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtain the shear line position based on the width of the medium-thick plate and edge linearity detection.

[0101] S1: The calibration of the dual-line array cameras in the upper and lower surface profilers obtains two-dimensional images through relative motion with the object. First, a transparent calibration plate (high-contrast black and white checkerboard grid) is selected. Through the stable movement of the calibration plate, a complete two-dimensional image is generated by row-by-row scanning and stitching. Then, the checkerboard corner points in the image are extracted. Combining the known physical dimensions of the calibration plate, the internal parameters (focal length, principal point, distortion coefficient) and external parameters (rotation matrix and translation vector) of the camera are calculated through the calibration method. The imaging model of the line array camera forms a two-dimensional image through motion scanning, and its projection relationship is:

[0102] ;

[0103] Among them, is the pixel coordinate of the image plane, is the internal parameter matrix of the camera, including the focal length, principal point, and distortion coefficient, is the rotation matrix between the camera coordinate system and the world coordinate system, is the translation vector of the camera, is the three-dimensional point in the world coordinate system.

[0104] For the relative external parameter calibration of the dual cameras, obtain the relative position relationship between the two camera coordinate systems. Let the external parameters of the left camera ( ) and the right camera ( ) be and respectively. The relative external parameter of the right camera coordinate system relative to the left camera coordinate system is:

[0105] ;

[0106] ;

[0107] Among them, is the rotation matrix of the right camera coordinate system relative to the left camera coordinate system, is the translation vector of the right camera coordinate system relative to the left camera coordinate system.

[0108] After calibration, the accuracy of the results is evaluated by the reprojection error, and the internal and external parameters are saved.

[0109] S2: After the upper and lower surface profilers obtain the medium-thick plate images, use Bouguet stereo rectification. According to the calibration parameters obtained in S1, perform stereo rectification on the images, map the images to a coplanar plane to eliminate vertical parallax, and further calculate the rectification rotation matrix to achieve row alignment. First, define the baseline direction, construct an orthogonal basis, and build the rectification rotation matrix. Then, apply the average rotation to the left and right cameras, with each camera rotating by half, to make the image planes of the two cameras coplanar, correct the projection matrix, and achieve image row alignment. The implementation process of calculating the rectification rotation matrix is as follows:

[0110] ;

[0111] ;

[0112] ;

[0113] ;

[0114] ;

[0115] Among them, are respectively the components of the translation vector of the right camera coordinate system relative to the left camera coordinate system in the direction, is the pole in the same direction as the translation vector, is the vector in the direction of the image plane, is the vector perpendicular to the plane where is located,

[0116] Applying the rotation matrix, the two-camera planes are coplanar, calculate the corrected projection matrix, convert the original image into the corrected image, eliminate distortion and perspective differences, and the implementation process of achieving image row alignment is as follows:

[0117] ;

[0118] ;

[0119] ;

[0120] ;

[0121] ;

[0122] Among them, is the calibration rotation matrix of the left camera, is the calibration rotation matrix of the right camera, is the unified calibration internal parameter matrix, is the projection matrix of the left camera, is the projection matrix of the right camera.

[0123] For the pixel points in the left camera image, find their matching points in the right camera image. Calculate the pixel difference between the corresponding points in the two images to obtain the disparity, that is, calculate the horizontal displacement of the same object in the two images. According to the relationship between the disparity and the depth, convert the disparity map into a depth map, and calculate the corresponding depth value according to the disparity. The depth map provides the spatial position of each pixel point and can be used for further three-dimensional analysis and applications. The implementation methods for calculating the disparity map and the depth map are as follows:

[0124] ;

[0125] ;

[0126] Where: is the pixel difference between the pixel points in the left camera image and the pixel points in the right image, and respectively represent the horizontal coordinates of the corresponding points in the two images, is the depth corresponding to this pixel, is the camera focal length, is the baseline between the two cameras (the horizontal distance between the two cameras).

[0127] Based on the ideal imaging model of the binocular camera, under the conditions of image row correction and coplanarity, using the disparity map and the pixel coordinate difference, combined with the internal and external parameters of the camera, calculate the coordinates of each pixel point in the three-dimensional space to generate the point cloud data on the surface of the medium plate. The pixel coordinates of the left camera are , and the pixel coordinates of the right camera are . According to the imaging geometric relationship of the binocular camera, the coordinates in the three-dimensional space are calculated as follows:

[0128] ;

[0129] ;

[0130] ;

[0131] Where: is the baseline between the two cameras (the horizontal distance between the two cameras). and are the horizontal pixel coordinates in the left and right camera images, and is the vertical pixel coordinate in the left and right camera images, is the pixel difference between the pixel points in the left camera image and the pixel points in the right image, is the camera focal length.

[0132] Specifically, feature extraction is performed on the obtained medium-thick plate image, stereo matching is carried out, a disparity map is generated, and three-dimensional coordinate information is calculated through the disparity. The double cameras on both sides of the medium-thick plate are symmetrically placed with respect to the roller table surface. According to the geometric relationship, the coordinate systems of the point cloud images on the upper and lower surfaces of the medium-thick plate are transformed into the same coordinate system.

[0133] S3: Due to problems such as noise, environmental dust, uneven illumination, motion error, and projection distortion, interference points are generated in the point cloud images on the upper and lower surfaces of the medium-thick plate after three-dimensional reconstruction. Low-density points or abnormal distance points are detected through statistical characteristic analysis. Low-density points refer to the points in a certain local area of the point cloud where the distribution density is significantly lower than the surrounding area (such as data loss caused by dust occlusion or sensor failure), and abnormal distance points refer to the points in the point cloud where the vertical distance from the surface of the medium-thick plate deviates significantly from the normal range (such as outliers caused by motion error or projection distortion). Combining the local curvature calculation method and the normal vector consistency analysis, the point clouds that do not conform to the plane characteristics of the medium-thick plate are removed. After removing the interference points, the nearest neighbor interpolation is used to repair the vacant area. For the holes formed by low-density or removed points, the mean value of the nearest neighbor coordinates of the surrounding valid points is taken as the interpolation to ensure the integrity and consistency of the point cloud data.

[0134] Specifically, low-density points or abnormal distance points are detected through statistical characteristic analysis. Combining the local curvature calculation method and the normal vector consistency analysis, interference points are removed from the point cloud image after three-dimensional reconstruction, and the nearest neighbor interpolation is used to repair the vacant area. The point cloud planes of the upper and lower surfaces are fitted. The center lines are calculated respectively, and the offset and rotation amounts are judged through the relationship between the center lines. A rigid body transformation matrix is constructed for correction.

[0135] S4: Convert the point cloud coordinate system generated by the lower profiler to the point cloud coordinate system of the upper profiler. The upper and lower profilers are symmetrically placed with respect to the roller table surface. The corresponding simplified rotation matrix and translation vector are:

[0136] ;

[0137] where, and respectively represent the distances from the upper and lower profilers to the roller table surface.

[0138] Through the rotation matrix and translation vector, the point cloud image coordinate system generated by the lower profiler is transformed into the point cloud image coordinate system generated by the upper profiler.

[0139] S5: During the movement of the medium-thick plate, due to the friction with the roller path 7 or the action of lateral force, the medium-thick plate may rotate around its central axis (around the Z-axis), or tilt around the transverse and longitudinal axes (around the X and Y axes). Perform point cloud plane fitting on the upper and lower surfaces. Calculate the center lines respectively, and judge the offset and rotation amount through the relationship between the center lines. Use the RANSAC algorithm to perform plane fitting on the upper and lower surfaces of the medium-thick plate, and the fitting formula is:

[0140] ;

[0141] where, is the fitting parameter, is the coordinate of the point in the three-dimensional point cloud.

[0142] Select the parallel cross-section point clouds with a fixed interval on the upper and lower surfaces respectively (take a section of point cloud at a certain distance along the length direction of the medium-thick plate), and calculate the geometric center of each cross-section:

[0143] ;

[0144] where, the geometric center point of the cross-section is the coordinate average value (centroid) of all the point clouds in a certain slice cross-section, the number of point clouds in the current cross-section, <00S5: During the movement of the medium-thick plate, due to the friction with the roller path 7 or the action of lateral force, the medium-thick plate may rotate around its central axis (around the Z-axis), or tilt around the transverse and longitudinal axes (around the X and Y axes). Perform point cloud plane fitting on the upper and lower surfaces. Calculate the center lines respectively, and judge the offset and rotation amount through the relationship between the center lines. Use the RANSAC algorithm to perform plane fitting on the upper and lower surfaces of the medium-thick plate, and the fitting formula is:

[0140] ;

[0141] where, is the fitting parameter, is the coordinate of the point in the three-dimensional point cloud.

[0142] Select the parallel cross-section point clouds with a fixed interval on the upper and lower surfaces respectively (take a section of point cloud at a certain distance along the length direction of the medium-thick plate), and calculate the geometric center of each cross-section:

[0143] ;

[0144] where, the geometric center point of the cross-section is the coordinate average value (centroid) of all the point clouds in a certain slice cross-section, the number of point clouds in the current cross-section, index variable, indicating that the current being accumulated is the th point, and the value range is from 1 to , is the point cloud coordinate on the cross-section.

[0145] Connect all the cross-section center points to obtain the center lines of the upper and lower surfaces. The center lines of the upper and lower surfaces should theoretically coincide, but due to the deformation of the medium-thick plate and measurement errors in actual measurement, there is an offset, and the offset vector is:

[0146] ;

[0147] where, and are the center point coordinates of the upper and lower surfaces respectively.

[0148] Use the angle between the normal vectors of the upper and lower surfaces to directly construct a rotation matrix through the rotation formula:

[0149] ;

[0150] where, and are the normal vectors of the upper and lower surfaces respectively.

[0151] According to the offset and rotation amount calculated above, construct a rigid body transformation matrix:

[0152] ;

[0153] Perform a rigid body transformation on the point clouds of the upper and lower surfaces:

[0154] ;

[0155] Among them, is the original point cloud, is the corrected point cloud.

[0156] By fitting the center lines of the point clouds on the upper and lower surfaces of the medium-thick plate and analyzing the plane normal vectors, the offset and rotation angles are accurately calculated. After correction using the rigid body transformation matrix, the normal vectors of the corrected upper and lower surface point clouds are parallel, and the included angle of the fitting plane tends to zero.

[0157] S6: After eliminating the offset and rotation, eliminate the vibration influence through the point cloud data of the upper and lower surfaces. The vibration of the medium-thick plate usually shows small periodic or random fluctuations in the point cloud data, which is manifested as the vertical distance fluctuation between the local undulating center lines in the point cloud image, or abnormal local curvature of the point cloud. Step 5 has corrected the deviation of the upper and lower surface point clouds, and the local vibration and thickness change can be quantified by directly comparing the geometric relationship between the upper and lower surface point clouds.

[0158] Specifically, use frequency domain analysis to extract the vibration error components, calculate the offset vector, and adjust along the normal vector direction. After eliminating the vibration error, the point clouds on the upper and lower surfaces of the medium-thick plate are divided into several small regions, and the average thickness of the points in each region is calculated, and finally the thickness distribution and overall thickness statistics of the medium-thick plate are obtained.

[0159] Adopt the nearest neighbor point matching to make each point in the upper and lower surface point clouds find the corresponding relationship, and calculate the vertical distance between each pair of matching points on the upper and lower surfaces.

[0160] ;

[0161] Among them, is the projection distance of the point cloud on the normal vector, and are the corresponding points on the upper and lower surfaces respectively, is the global normal vector.

[0162] Perform a fast Fourier transform on to extract the main frequency distribution:

[0163] ;

[0164] Among them, is the frequency component of the vibration signal obtained by the fast Fourier transform, is the index of the discrete data points, is the total number of data points in the input signal, is the projection distance of the point cloud on the normal vector, is the complex exponential basis function of the Fourier transform.

[0165] The low-frequency component is the whole medium-thick plate, and the high-frequency component may be the error caused by vibration. Set the vibration frequency range to , and use a band-pass filter to extract the vibration signal:

[0166] ;

[0167] Among them, is the vibration error signal after frequency-domain filtering, are the upper and lower limits of the vibration frequency range, is the frequency component of the vibration signal, is the complex exponential basis function of the inverse Fourier transform.

[0168] Use frequency-domain analysis to extract the vibration error component , which represents the vertical vibration between the upper and lower surfaces of the medium-thick plate, and calculate the offset vector , and adjust it along the normal vector direction.

[0169] ;

[0170] For the original coordinates of each pair of point clouds, adjust the point cloud according to the vibration component:

[0171] ;

[0172] Among them, is the corrected point coordinate, is the original point coordinate of the upper surface before correction, is the corresponding original point coordinate of the lower surface before correction, is the offset vector.

[0173] By correcting the error between the corresponding point clouds on the upper and lower surfaces of the medium-thick plate, the vibration influence of the medium-thick plate is eliminated.

[0174] S7: Process the point cloud data of the upper and lower surfaces that have been corrected by vibration elimination and error compensation, and remove the isolated points and noise points in the point cloud. By dividing the point cloud of the upper and lower surfaces of the medium-thick plate into several small regions (grids), calculate the average thickness of the points in each grid, and finally obtain the thickness distribution of the medium-thick plate. Remove the grid regions with anomalies (locally thin regions or regions with excessive thickness), and calculate the overall thickness of the medium-thick plate.

[0175] ;

[0176] ;

[0177] Among them, is the number of divided grids, is the average thickness within the th grid area, is the number of points within the th grid, is the thickness between the th point cloud and the corresponding point within the grid, is the overall average thickness of the medium - thick plate, is the total number of grid areas after removing abnormal grid areas, is the index of the number of grid areas after removing abnormal grid areas, is the average thickness of the grid area after removing abnormal grid areas.

[0178] The grid - based average thickness method divides the upper and lower surface point clouds into small areas and calculates the average thickness grid by grid , and the average thickness of each grid area corresponds to a color value. Using color gradient to map the thickness value to color, the thicker area of the medium - thick plate is shown as a darker color, and the relatively thinner area is shown as a lighter color. Finally, a regional thickness distribution map of the medium - thick plate is generated, which can identify the local variable thickness of the medium - thick plate, facilitate quality assessment and defect location, and simplifies the complexity of global point matching by means of grid division.

[0179] S8: After processing the upper and lower surface point clouds of the medium - thick plate, the point cloud data has been aligned and noise removed, and has high precision and consistency. On this basis, project the point cloud onto a two - dimensional plane and extract edge points through an edge detection algorithm. Use the moving average method to remove local noise from the extracted edge point set to obtain a smooth edge point set. The moving average formula is:

[0180] ;

[0181] Among them, is the moving window size, is the index of the points in the moving window, from to , indicating that the coordinates of all points within the window range will participate in the calculation. is the index of the currently calculated point, is the unsmoothed edge point, is the smoothed edge point.

[0182] Sparse region detection is performed on the smoothed edge point set. If the number of points in some regions is small or there are obvious blanks, triangulation can be used to fill in the missing regions. For the complete edge point set, spline interpolation is used to smooth these edge points to obtain a smoother boundary curve. The cubic spline interpolation formula is:

[0183] ;

[0184] where is the value of the interpolation curve at , is the independent variable of the interpolation, is the index of the current interpolation segment, are two adjacent known edge points, is the abscissa of the previous edge point of the current interpolation point, is the abscissa of the next edge point of the current interpolation point, are the spline interpolation coefficients, which are obtained by solving a system of linear equations to ensure that the curve is continuous and smooth at each interpolation point.

[0185] Through the above steps, a smooth, closed and complete medium-thick plate contour line is finally generated, which can accurately reflect the shape characteristics and dimensional information of the medium-thick plate. This contour line not only has high precision in geometric shape, but also has good continuity and smoothness, and can be comprehensively used for subsequent shearing of irregular shapes at the head and tail of the plate. At the same time, this high-precision contour line also provides reliable basic data for process analysis, optimizes the processing process, controls the production accuracy, and further improves the overall quality and efficiency of the medium-thick plate manufacturing process.

[0186] S9: Obtain the width of the medium-thick plate through the medium-thick plate specification model parameters . According to the width of the medium-thick plate, calculate the corresponding width point by point for the head and tail regions of the medium-thick plate contour, construct a width sequence and preliminarily determine the possible cutting positions according to the significant changes in the width. The corresponding width sequence is . To ensure the accuracy of the cutting line, it is necessary to further accurately determine the rough positioning result and propose a precise positioning method for the cutting line based on width consistency and edge linearity. Judge whether the width sequence within the region remains consistent. If the width consistency condition (width fluctuation within the specified threshold) is met, it is considered that the region is suitable for cutting. Detect the continuous sub-regions of the width sequence , and set the starting index as . If the following conditions are met, it is considered that the width of the region is consistent:

[0187] ;

[0188] where is the detection range length, is the width consistency threshold. The width consistency detection ensures that the width fluctuation within the cropping area is small, thus avoiding cropping errors caused by local abnormal widths.

[0189] Within the area that meets the width consistency, the left and right edge points of each row are further extracted, and the fitting residuals are calculated through linear fitting to determine whether the edges have good linearity. By comparing the maximum value of the fitting residuals with the set threshold, it is accurately determined whether the left and right edges are straight, thereby further locking the optimal cropping position to ensure that the cropped edges are smooth. This method realizes multiple screenings from width determination to edge shape detection, providing a reliable basis for the final precise positioning of the cutting line and ensuring the cropping quality.

[0190] Embodiment 2

[0191] The present invention discloses a double-sided contour measurement system for medium-thick stainless steel plates. The system is used to implement any of the methods described above. The system includes: an image acquisition unit, a 3D reconstruction unit, a motion correction unit, a thickness measurement and error correction unit, and a contour detection and cutting position unit;

[0192] The image acquisition unit is used to complete the calibration of the double-line array camera to obtain the images of the upper and lower surfaces of the medium-thick stainless steel plate;

[0193] The 3D reconstruction unit is used to perform binocular stereo vision 3D reconstruction on the images of the upper and lower surfaces of the medium-thick stainless steel plate to generate a point cloud map and convert it for display in the same coordinate system;

[0194] The motion correction unit is used to eliminate lateral rotation and offset according to the fitting of the centerlines of the point clouds on the upper and lower surfaces of the medium-thick plate and plane fitting;

[0195] The thickness measurement and error correction unit is used to compare the geometric relationship between the point clouds on the upper and lower surfaces to quantify local vibrations and thickness changes, correct the vibration errors, and obtain the thickness of the medium-thick plate;

[0196] The contour detection and cutting position unit is used to extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtain the cutting line position based on the width and edge linearity detection of the medium-thick plate.

[0197] In this embodiment, the rolled medium - thick plate is smoothly laid on the roller table 7. The roller table 7 serves as a transportation and support device to ensure the stable position and flat surface of the medium - thick plate during movement. The surface of the roller table 7 is arranged opposite to the upper and lower surface profilers to ensure a good relative position relationship between the surface of the medium - thick plate and the field of view of the profilers during the scanning process. Each of the upper and lower surface profilers consists of two high - precision linear array cameras. Among them, the two cameras of each profiler 1 are arranged side by side, and the total field of view completely covers the entire transverse width of the medium - thick plate. There is a partially overlapping area in the field of view of the two cameras for subsequent binocular stereo vision 3D reconstruction to ensure measurement accuracy and data integrity. When the medium - thick plate moves to a specific position on the roller table 7, synchronous acquisition is achieved through the sensor trigger device on the roller table 7. The upper profiler acquires images of the upper surface of the medium - thick plate through the two cameras above the roller table 7, and the lower profiler acquires images of the lower surface of the medium - thick plate through the two cameras below the roller table 7. To ensure image quality, a uniformly scattering linear light source 3 is equipped on the upper surface, and a high - power linear light source 3 is equipped on the lower surface, providing uniform and sufficient illumination for the upper and lower profilers respectively to avoid the influence of insufficient light or reflection on image clarity. To reduce the interference of dust, vibration and oil stains, the profilers 1 are all installed in the enclosed metal protection box 2. A transparent high - temperature resistant glass window is set inside the protection box, and an automatic cleaning device 4 is equipped to ensure the stability of the long - term operation of the equipment.

[0198] Through the above arrangement and design, the profile detection system can efficiently acquire the upper and lower surface images of the medium - thick plate during the movement of the medium - thick plate. By using an accurate trigger synchronization mechanism and high - quality image acquisition conditions, it provides reliable high - precision original images, providing solid data support for subsequent 3D reconstruction, point cloud processing, and analysis tasks such as obtaining the overall profile, thickness distribution and shear line positioning of the medium - thick plate.

[0199] In this embodiment, the image acquisition unit mainly consists of the profiler 1 integrating two linear array cameras, the synchronous trigger 5, the linear light source 3, etc. When the medium - thick plate moves to a specific position on the roller table 7, synchronous acquisition is achieved through the sensor or trigger device on the roller table 7. The upper profiler acquires images of the upper surface of the medium - thick plate through the two cameras above the roller table 7, and the lower profiler acquires images of the lower surface of the medium - thick plate through the two cameras below the roller table 7.

[0200] In this embodiment, binocular stereo vision is used for 3D reconstruction to generate a point cloud map and convert it for display in the same coordinate system. Through the fitting of the centerlines and planes of the point clouds on the upper and lower surfaces of the medium plate, lateral rotation and offset are eliminated. By comparing the geometric relationships between the point clouds on the upper and lower surfaces, local vibrations and thickness changes are quantified, and the vibration errors are corrected to obtain the thickness of the medium plate. Edge point sets are extracted from the point cloud map to obtain the overall contour of the medium plate, and based on the detection of the width and edge linearity of the medium plate, the position of the shearing line is accurately located. Each functional unit works in cooperation to achieve high-precision measurement and positioning of the overall contour, thickness distribution, and shearing position of the medium plate.

[0201] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for measuring the double-sided profile of medium-thick stainless steel plates, characterized in that, The method includes: S1. Complete the calibration of the dual-line array camera to obtain the images of the upper and lower surfaces of the stainless steel medium-thick plate; S2. Perform binocular stereo vision 3D reconstruction on the images of the upper and lower surfaces of the stainless steel medium-thick plate to generate a point cloud map, and transform it to be displayed in the same coordinate system; S3. Eliminate the lateral rotation and offset according to the center line fitting and plane fitting of the point clouds on the upper and lower surfaces of the medium-thick plate; S4. Compare the geometric relationships between the point clouds on the upper and lower surfaces to quantify the local vibration and thickness change, correct the vibration error, and obtain the thickness of the medium-thick plate; S5. Extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtain the shearing line position based on the width and edge linearity detection of the medium-thick plate; In S4, comparing the geometric relationships between the point clouds on the upper and lower surfaces to quantify the local vibration and thickness change, correct the vibration error, and obtain the thickness of the medium-thick plate includes: Use frequency domain analysis to extract the vibration error component, calculate the offset vector, and adjust along the normal vector direction; After eliminating the vibration error, divide the point clouds on the upper and lower surfaces of the medium-thick plate into several small regions, calculate the average thickness of the points in each region, and finally obtain the thickness distribution and overall thickness statistics of the medium-thick plate; Use frequency domain analysis to extract the vibration error component, calculate the offset vector, and adjust along the normal vector direction includes: Adopt nearest neighbor point matching to make each point in the point clouds on the upper and lower surfaces find the corresponding relationship, and calculate the vertical distance between each pair of matching points on the upper and lower surfaces; ； wherein, is the projection distance of the point cloud on the normal vector, and are the corresponding points on the upper and lower surfaces respectively, is the global normal vector; For perform a fast Fourier transform to extract the main frequency distribution: ； Among them, is the frequency component of the vibration signal obtained by fast Fourier transform, is the index of discrete data points, is the total number of data points in the input signal, is the projection distance of the point cloud on the normal vector, is the complex exponential basis function of Fourier transform; Set the vibration frequency range according to the main frequency distribution as , and use a band-pass filter to extract the vibration signal: ； Among them, is the vibration error signal after frequency-domain filtering, are the upper and lower limits of the vibration frequency range, is the frequency component of the vibration signal, is the complex exponential basis function of the inverse Fourier transform; Extract vibration error components using frequency domain analysis , representing the vertical vibration between the upper and lower surfaces of the medium-thick plate, calculate the offset vector , adjust along the normal vector direction; ； For the original coordinates of each pair of point clouds, adjust the point clouds according to the vibration component; ； Among them, is the corrected point coordinate, is the original upper surface point coordinate before correction, is the corresponding original lower surface point coordinate before correction, is the offset vector; Eliminate the influence of the vibration of the medium-thick plate by correcting the error between the corresponding point clouds on the upper and lower surfaces of the medium-thick plate.

2. The double-sided profile measurement method of medium and heavy stainless steel plates according to claim 1, wherein, In S1, the calibration of the dual-line array camera includes: Select a transparent calibration plate, and through the stable movement of the calibration plate, scan and splice line by line to generate a complete two-dimensional image; Extract the feature points in the two-dimensional image, combine the known physical dimensions of the calibration plate, and optimize and calculate the internal and external parameters of the camera through the calibration algorithm; Calibrate the geometric relationship of the dual-line array camera.

3. The method for measuring the double-sided profile of medium and heavy stainless steel plates according to claim 1, characterized in that, In S2, performing binocular stereo vision 3D reconstruction on the images of the upper and lower surfaces of the stainless steel medium-thick plate to generate a point cloud map includes: After obtaining the images of the upper and lower surfaces of the stainless steel medium-thick plate, perform stereo correction on the images according to the calibration parameters, and map the images to a coplanar plane to eliminate the vertical parallax; Use the stereo matching algorithm to calculate the disparity map, and generate depth information through the position difference of the corresponding pixel points in the two images; According to the disparity map and the internal and external parameters of the camera, project the pixel points into the three-dimensional space to generate the point cloud data of the surface of the medium-thick plate.

4. The method for measuring the double-sided profile of the medium-thick stainless steel plate according to claim 1, wherein, In S3, eliminating the lateral rotation and offset according to the center line fitting and plane fitting of the point clouds on the upper and lower surfaces of the medium-thick plate includes: Detect the low-density points or abnormal distance points through the statistical characteristic analysis method, combine the local curvature calculation method and the normal vector consistency analysis, remove the interference points from the point cloud image after 3D reconstruction, and use the nearest neighbor interpolation to repair the vacant area; Perform plane fitting on the point clouds on the upper and lower surfaces, calculate the center lines respectively, and judge the offset and rotation amounts through the relationship between the center lines, and construct a rigid body transformation matrix for correction; Among them, performing plane fitting on the point clouds on the upper and lower surfaces includes: Use the RANSAC algorithm to perform plane fitting on the upper and lower surfaces of the medium-thick plate, and the fitting formula is: ； Among them, is a fitting parameter, is the coordinate of a point in the three-dimensional point cloud; Calculating the center line includes: Select parallel cross-section point clouds at fixed intervals on the upper and lower surfaces respectively, and calculate the geometric center of each cross-section: ； Among them, The cross-sectional geometric center point is the coordinate average value, i.e., the centroid, of all point clouds within a certain slice cross-section. The number of point clouds within the current cross-section The index variable indicates that the th point is currently being accumulated, and its value ranges from 1 to , is the point cloud coordinate on the cross-section; Connect all the center points of the cross-sections to obtain the center lines of the upper and lower surfaces; Judging the offset and rotation amounts through the relationship between the center lines includes: ； Among them, and are the central point coordinates of the upper and lower surfaces respectively; Constructing a rigid body transformation matrix for correction includes: According to the offset and rotation amounts calculated above, construct a rigid body transformation matrix: ； Among them, is a rotation matrix; Perform rigid body transformation on the point clouds of the upper and lower surfaces: ； Among them, is the original point cloud, is the corrected point cloud.

5. The method for measuring the double-sided profile of medium-thick stainless steel plates according to claim 1, wherein After eliminating the vibration error, divide the point clouds of the upper and lower surfaces of the medium-thick plate into several small regions, calculate the average thickness of the points in each region, and finally obtain the thickness distribution and overall thickness statistics of the medium-thick plate, including: For each grid region, calculate the average thickness of all point pairs in the region: ； Among them, is the number of points within the grid; Use the grid-based average thickness method to divide the point clouds of the upper and lower surfaces into small regions, calculate the average thickness grid by grid, and finally generate the regional thickness distribution map of the medium-thick plate; According to the regional thickness distribution map of the medium-thick plate, identify the locally varying thickness of the medium-thick plate, and finally obtain the overall thickness of the medium-thick plate.

6. The method for measuring the double-sided profile of the medium-thick stainless steel plate according to claim 1, wherein, In S5, extracting the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtaining the shear line position based on the width and edge linearity detection of the medium-thick plate includes: Obtain the width of the medium plate through the medium plate specification model parameters ; According to the width of the medium plate , calculate the corresponding width point by point for the head and tail regions of the medium plate contour, and construct a width sequence And based on the change of the width, preliminarily determine the cutting position, and the corresponding width sequence is ; Determine whether the width sequence within the judgment area remains consistent. If the width consistency condition is met, that is, the width fluctuation is within the specified threshold, then it is considered that the area is suitable for cropping, and the continuous sub-areas of the width sequence are detected. Let the starting index be . If the preset condition is met, then it is considered that the width of this area is consistent; among them, the preset condition is: ； Among them, is the detection range length, is the width consistency threshold; In the region where the width consistency is satisfied, extract the left and right edge points of each row, and judge whether the edge meets the preset linearity requirement by calculating the fitting residual through linear fitting, that is, compare the maximum value of the fitting residual with the set threshold to accurately judge whether the left and right edges are straight, so as to lock the optimal cutting position and ensure that the cut edge is flat and smooth.

7. A double-sided profile measurement system for medium-thick stainless steel plates, the system being used to implement the double-sided profile measurement method for medium-thick stainless steel plates described in any one of claims 1-6, characterized in that, The system includes: an image acquisition unit, a 3D reconstruction unit, a motion correction unit, a thickness measurement and error correction unit, and a contour detection and shear positioning unit; The image acquisition unit is used to complete the calibration of the double-line array camera to obtain the images of the upper and lower surfaces of the stainless steel medium-thick plate; The 3D reconstruction unit is used to perform binocular stereo vision 3D reconstruction on the images of the upper and lower surfaces of the stainless steel medium-thick plate to generate a point cloud map and display it in the same coordinate system; The motion correction unit is used to eliminate the lateral rotation and offset according to the center line fitting and plane fitting of the point clouds of the upper and lower surfaces of the medium-thick plate; The thickness measurement and error correction unit is used to compare the geometric relationship between the point clouds of the upper and lower surfaces to quantify the local vibration and thickness change, correct the vibration error, and obtain the thickness of the medium-thick plate; The contour detection and shear positioning unit is used to extract the edge point set from the point cloud map to obtain the overall contour of the medium-thick plate, and obtain the shear line position based on the width and edge linearity detection of the medium-thick plate.

Images