A method for calibrating a steel sheet shape measurement

Abstract

The application provides a steel plate shape measurement calibration method, belongs to the field of three-dimensional shape measurement and calibration, and aims to realize three-dimensional reconstruction and shape measurement of a steel plate surface. In order to realize high-precision detection of the plate shape, the application obtains X, Y and Z coordinate data of the steel plate surface through a double-line laser measurement system. The measurement system is composed of multiple cameras and two line lasers, the installation positions of the cameras are determined to ensure that the cameras have a certain overlapping field of view, so that the data can be spliced. In the measurement process, the image captured by the camera is processed, the position information of the laser line in the image is extracted, the pixel coordinates are converted into actual world coordinates according to the calibration parameters and the working distance of the camera, and the X, Y and Z three-dimensional coordinate data of the steel plate surface are obtained. Vibration compensation is carried out in the measurement process to ensure the accuracy and stability of the measurement result.

Description

Technical Field

[0001] This invention belongs to the field of three-dimensional shape measurement and calibration, and in particular relates to a method for measuring and calibrating the shape of a steel plate. Background Technology

[0002] With the development of modern technology, fields such as rail transportation, heavy equipment, military industry, and aerospace have placed higher demands on the shape accuracy of sheet metal. Straightening machines and flattening machines are the main equipment on sheet metal finishing production lines, and sheet shape data is the foundation for intelligent implementation during the sheet metal straightening process. The diverse specifications of sheet metal present challenges to sheet shape measurement systems. In recent years, the rapid development of vision technology has led to the rapid improvement of structured light measurement technology, characterized by its simple structure, high efficiency, and non-contact operation. Building a multi-camera structured light measurement system is an important way to obtain sheet shape data for various specifications of sheet metal and is also one of the key technologies for the intelligentization of metal rolling finishing equipment. A structured light measurement system generally consists of a camera, laser, fixing device, industrial control computer, and related algorithms. Its measurement principle mainly involves collecting deformation data of the laser line hitting the surface of the object through the camera, and calculating the three-dimensional point cloud data of the surface of the measured object. In a structured light measurement system, the calibration method and accuracy of the measurement system directly affect the system's practicality and measurement accuracy.

[0003] Current multi-camera, wide-field-of-view structured light measurement systems suffer from complex calibration processes, and most calibration methods involve multiple fitting processes. This leads to accumulated calibration errors, limiting the accuracy of structured light measurements under wide fields of view. Furthermore, vibrations during steel plate production severely impact the accuracy of structured light plate shape measurements. To address this, this patent proposes a novel steel plate shape calibration and measurement method. This method solves the problem of three-dimensional measurement of steel plate shapes of different specifications, resolves the impact of plate vibration on shape measurement, and features a simple calibration process that is easy to implement on-site. The structured light measurement system mainly consists of multiple industrial cameras, two line lasers, a fixing device, an industrial control computer, and related software. The combination of multiple cameras can meet the shape measurement needs of steel plates of different specifications. Summary of the Invention

[0004] To address the problem of low accuracy in steel plate shape measurement, this invention provides a method for calibrating steel plate shape measurement. This invention combines multiple cameras and a dual-line laser, along with vibration compensation technology, to achieve precise measurement of the surface shape of steel plates, providing reliable data support for quality control and process improvement during plate production.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a steel plate shape measurement and calibration method, including a calibration device and a measuring device. The calibration device includes a lifting device, a fixing device, a rotating device and a calibration plate. The calibration plate is installed on the upgrading device through the rotating device and can move with the lifting device. The upgrading device is fixed on both sides of the roller conveyor through the fixing device.

[0006] The measuring device includes multiple cameras and two line lasers. All cameras are fixed on the same horizontal plane at a certain distance apart, while the two lasers are placed in parallel and spaced apart from each other.

[0007] The calibration and measurement process is carried out according to the following steps:

[0008] S1. Place the calibration device on the roller conveyor of the steel plate shape measurement system and fix it. Determine the position where the upper surface of the calibration plate is flush with the surface of the steel plate to be measured as the unique reference plane. At this time, the working distance of the camera lens is H0.

[0009] S2. Raise the calibration plate to a height of ΔH using the lifting platform of the calibration device. At this time, the working distance of the camera lens is H2. Then, calculate the single pixel accuracy P0 of the camera, the difference between the laser center line coordinate and the image height center coordinate D0, the single pixel accuracy P2 of the camera, and the difference between the laser center line coordinate and the image height center coordinate D2 when the working distance of the camera lens is H0 and H2 respectively.

[0010] S3. A dual-line laser is used to perform three-dimensional reconstruction of the steel plate surface. The plate shape data represents the steel plate surface in the world coordinate system (X). w Y w Z w )coordinate;

[0011] S31, Z on the surface of the steel plate w Coordinate acquisition

[0012] Based on the calibration process and the inherent properties of the camera and lens, P0, P2, D0, D2, v0, v2, as well as the image height V, image width U, and lens field of view β are obtained. During the measurement process, the working distance of the camera lens is defined as H. x By establishing ΔH x (ΔHx=H) x The relationship between -H0 and these parameters is used to solve for ΔH. x Z w ;

[0013] During the measurement process, the position of the laser centerline changes depending on the height of the steel plate being measured. This situation is divided into five cases, and in each case, the principle of trigonometric similarity is used to calculate ΔH. x Establish a relationship with the calibration parameters;

[0014] S32, X on the surface of the steel plate w coordinate

[0015] The 3D data calculated by each camera are stitched together. During camera installation, the installation position of each camera is determined so that each camera has a certain common field of view. Several calibration objects are placed on the calibration board, and each calibration object is located within the common field of view of two adjacent cameras. Matching points are found by taking pictures of two cameras to obtain the spatial transformation matrix. Then, by utilizing the uniqueness of the world coordinate system of the calibration board with the same pose in the common field of view of adjacent cameras, the coordinate systems of multiple cameras are mapped to the reference coordinate system. Based on the uniqueness of the actual laser plane, the coordinate systems of multiple cameras are unified to the same pose, and the positional relationship of the point cloud data of adjacent cameras is determined by the unified coordinates.

[0016] S33, Y on the surface of the steel plate w coordinate

[0017] Y w Based on the moving speed and time of the steel plate, starting from the running time t=0, based on the moving speed V of the steel plate... p Y w The value is:

[0018] .

[0019] Furthermore, the specific calculation process of step S2 is as follows:

[0020] S21, Obtain P0

[0021] Below each pair of adjacent camera views, there is a calibration object on the calibration board. The side length of the first square in the calibration object in the real world is 'a'. Then, an image is taken. Next, the corner points of the black squares are detected by the program. By calculating the difference Δy between the v coordinates of the corner points in the image pixel coordinate system (that is, the number of coordinates occupied by the side length of a square in the image pixel coordinate system), the single pixel precision P0, i.e., a / Δy, can be obtained.

[0022] S22, Obtain D0

[0023] First, the gray-scale centroid method in the laser centerline extraction algorithm is used to obtain the laser centerline coordinates v0 under H0. Then, given the image height V and its center coordinates V / 2, we can obtain D0 = v0 - V / 2.

[0024] S23. Using the same method, P2 and D2 can be obtained when the working distance is H2.

[0025] Furthermore, in step S31, under the five different conditions, ΔH x The relationship with the calibration parameters is expressed by the following formula:

[0026] (a) when hour

[0027]

[0028] (b) When hour

[0029]

[0030] (c) When hour

[0031]

[0032] (d) When hour

[0033]

[0034] (e) When hour

[0035]

[0036] In the above formulas, the parameter ΔH = H2 - H0, and its value is directly obtained from the digital display of the calibration device. x During the measurement process, the coordinates v of the laser centerline are extracted. x P0, D0, P2, D2 have been obtained through calibration steps S1 and S2, ΔH x =H x -H 0, In the above formula, H x Unknown, P x unknown;

[0037] Based on the relationship between the various parameters of the camera lens, we can obtain equation (6).

[0038]

[0039] Based on equation (6), two unknowns H are established. x P x The relationship between them can be solved by combining them with equations (1) to (5) respectively, and then ΔH can be obtained in the five cases. x Z w ;

[0040] During the measurement process, based on the pixel position v of the light stripe in the obtained image... x Determine which situation it is in, and then, except for situation (c) where the result is obtained directly, all other cases require simultaneous calculation using equation (6). .

[0041] Furthermore, the measured Z needs to be... w Vibration compensation is performed using coordinates.

[0042] The measurement system has two laser lines, R1 and R2. The value of Z is calculated from these two laser lines at time t. w The value can be expressed by formulas (7) and (8).

[0043]

[0044]

[0045] When the measurement time interval is set to the time interval between the movement of the steel plate from R1 to R2, every Δt will cause the laser line of R1 to measure the same position as the laser line of R2 at the previous moment. Thus, the position of the steel plate measured by R2 at time t1 should be the same as the position measured by R1 at time t2, and the results should also be the same. However, due to vibration, a deviation of S1 occurs between the two.

[0046]

[0047] To eliminate vibration, add the vibration amount S1 to all measurements taken at time t2 and thereafter, and so on, at t i The measurement result at position R1 at time 1 will produce an S difference compared to the measurement result at position R2 at the previous time 2. i-1 The vibration value, which may be positive or negative, if the first measurement position is set at R2 at time t1, then at t i The height Z after vibration elimination when measuring the steel plate at all times. w The coordinates should be:

[0048] .

[0049] Furthermore, the X on the surface of the steel plate w The specific calculation process for the coordinates is as follows:

[0050] P iH P is the coordinate of the center of the marker to the right of the i-th camera. iL Let ΔL be the coordinates of the center of the marker to the left of the i-th camera. i It is the actual length of the i-th calibration object. It represents the number of pixels in the image occupied by the size of the left-hand calibration object under the i-th camera. It represents the number of pixels occupied by the right-hand calibration object under the i-th camera in the image. It is the actual size represented by a unit pixel of the i-th camera, according to formula (11), and substituted with the working distance H of the i-th camera based on the reference plane. ij We can obtain:

[0051]

[0052] ΔH i This indicates the height increase of the area during stitching, with the first camera as the reference, and the coordinates increasing sequentially to the right. Formula (12) represents the calculation of the coordinates of the three-dimensional data of the plate shape in the width direction when there are n cameras. It is the image height of the nth camera:

[0053] .

[0054] The advantages and positive effects of this invention are as follows: This invention primarily utilizes a designed calibration device to quantify the positional relationship of the laser line within the camera, and considers the differences in the actual size represented by pixels at different distances between the target object and the camera when calculating 3D data, thereby compensating for the influence of the undulating shape of the board material on measurement errors. Simultaneously, based on a vibration compensation calculation method, the impact of vibration on 3D measurement is reduced. Finally, based on the relative positional relationship of each camera, the point cloud data from multiple cameras are stitched together, unifying the multi-camera measurement data under a reference coordinate system, thus realizing the measurement of the shape data of sized board materials. Attached Figure Description

[0055] Figure 1 This is a front view of the calibration device of the present invention.

[0056] Figure 2 This is a top view of the calibration device.

[0057] Figure 3 Left view of the calibration device.

[0058] Figure 4 This is a schematic diagram of a measurement system based on multiple cameras.

[0059] Figure 5 This is a schematic diagram of the calibration principle.

[0060] Figure 6 This is a schematic diagram illustrating the principle of plate shape data calculation.

[0061] Figure 7 This is a schematic diagram showing the relationship between the field of view and the working distance.

[0062] Figure 8 This is a schematic diagram illustrating the principle of vibration compensation calculation.

[0063] Figure 9 This is a schematic diagram of three-dimensional data stitching. Detailed Implementation

[0064] To make the objectives, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below.

[0065] A method for measuring and calibrating the shape of a steel plate mainly consists of two parts: calibration and measurement. Each step requires a corresponding hardware device. First, a brief introduction to the hardware device involved in this invention will be given.

[0066] like Figures 1-3 As shown, the calibration device mainly consists of four parts: a lifting device, a fixing device, a rotating device, and a calibration plate. First, the lifting device uses a high-precision, heavy-duty digital display lifting platform. To ensure accuracy, the lifting height accuracy of the platform is no less than 0.05 mm, and the reading accuracy of the side-mounted digital display device is 0.01 mm, to obtain the precise value of the calibration plate's lifting height.

[0067] Secondly, the fixing device is constructed of aluminum profiles in a rectangular frame, with fixing plates on both sides for securing the lifting platform. The rotating mechanism is designed to prevent deformation of the calibration plate during lifting due to uneven heights on both sides. Furthermore, to increase bending strength, two aluminum profiles are welded to the lower surface of the calibration plate to resist deformation caused by gravity. A checkerboard calibration plate is placed on its upper surface for calculating calibration parameters.

[0068] like Figure 4 As shown, the steel plate shape measurement system includes multiple cameras and two line lasers. All cameras are fixed on the same horizontal plane at a certain distance apart, while the two lasers are placed parallel to each other at a distance. The number of cameras can be determined according to the specifications of the steel plate.

[0069] The specific hardware structure involved in this invention has been briefly described above. The calibration principle of this invention will be briefly introduced below to facilitate those skilled in the art to understand the calibration measurement method of this invention.

[0070] like Figure 5 As shown, the calibration method proposed in this invention derives the three-dimensional height of the steel plate surface based on the change in the position of the laser line in the image height. Therefore, the main purpose of calibration is to determine the conversion relationship between pixels and height.

[0071] To obtain height information from the position of laser lines in an image, this invention proposes a direct pixel offset calibration method. First, the camera imaging model is simplified to a projection model, based on... Figure 5 The relationship shown indicates that the triangular projection formed by the camera's optical center and any column v parallel to the pixel coordinate u is OAB. On the OAB plane, when the height changes by ΔH, the target object will experience a pixel offset of Δδ on the image imaging plane under laser illumination. Based on this relationship, we propose a calibration method and design a calibration device, such as... Figures 1-3 As shown, the device can not only move the calibration plate up and down freely, but also display the amount of movement of the calibration plate in real time.

[0072] Moving the calibration plate up and down causes a pixel offset Δδ in the laser line coordinates, and simultaneously changes the working distance H of the camera lens, thus affecting the field of view and consequently altering the single-pixel accuracy. However, to improve accuracy during measurement, this effect needs to be minimized. Therefore, during calibration, the single-pixel accuracy P at different working distances must be calculated. i This is then incorporated into the derivation of the surface height of the three-dimensional steel plate.

[0073] Therefore, the calibration process is essentially the process of determining the following parameters.

[0074] H i The working distance of a camera lens is the distance between the lens and the object being measured.

[0075] P i The working distance of the camera lens is H. i At that time, the camera's single-pixel precision (i.e., the actual size represented by a single pixel in an image captured by the camera).

[0076] D i The working distance of the camera lens is H. i At that time, the difference between the coordinates of the laser centerline and the coordinates of the image height center.

[0077] v i The working distance of the camera lens is H. i At that time, the V-direction coordinate in the pixel coordinate system of the laser centerline image.

[0078] Based on the above hardware structure and calibration principle, the specific calibration and measurement process of this invention will be described in detail.

[0079] S1. Place and fix the calibration device on the roller conveyor of the steel plate shape measurement system. Then determine the position where the upper surface of the calibration plate is flush with the surface of the steel plate to be measured as the unique reference plane. At this time, the working distance of the camera lens is H0.

[0080] S2. Raise the calibration plate by a height ΔH using the lifting platform of the calibration device. At this point, the working distance of the camera lens is H2. Calculate P0 and D0, and P2 and D2 at the two working distances respectively. The specific steps are as follows:

[0081] S21, Obtain P0

[0082] Below each pair of adjacent camera views, there is a calibration object on the calibration board. The side length of the first square in the calibration object in the real world is 'a' (as above). Figure 2(As shown), and then take a picture. Next, use the program to detect the corner points of the black squares, and by calculating the difference Δy between the v coordinates of the corner points in the image pixel coordinate system (that is, the number of coordinates occupied by the side length of a square in the image pixel coordinate system), the single pixel precision P0, i.e., a / Δy, can be obtained.

[0083] S22, Obtain D0

[0084] First, the gray-scale centroid method in the laser centerline extraction algorithm (which has the advantages of high speed, high accuracy, and the ability to achieve sub-pixel accuracy in centerline extraction) is used to obtain the laser centerline coordinates v0 under H0. Then, given the image height V, its center coordinates are V / 2. Therefore, D0 = v0 - V / 2 can be obtained.

[0085] Using the same method, P2 and D2 can be obtained when the working distance is H2.

[0086] S3. Steel plate shape measurement involves three-dimensional reconstruction of the steel plate surface. The shape data represents the steel plate surface in the world coordinate system (X...). w Y w Z w The coordinates of the steel plate surface are used in this invention to perform three-dimensional reconstruction using a dual-line laser (as shown above). Figure 4 (As shown).

[0087] S31, Z on the surface of the steel plate w coordinate

[0088] Based on the calibration process and the inherent properties of the camera and lens, we can obtain P0, P2, D0, D2, v0, v2, as well as the image height V, image width U, and lens field of view β. During the measurement process, the working distance of the camera lens is defined as H. x (i.e., the distance between the steel plate to be measured and the camera lens), by establishing ΔH x (ΔH) x =H x The relationship between -H0 and these parameters is used to solve for ΔH. x Z w .

[0089] During the measurement process, the position of the laser centerline changes depending on the height of the steel plate being measured. This can be categorized into five cases. In each case, the principle of trigonometric similarity is used to calculate ΔH. x Establish a relationship with the calibration parameters. For example... Figure 6 As shown.

[0090] according to Figure 6 The similar triangle relationships in (a) to (e) can be derived from the following formula:

[0091] (a) when hour

[0092]

[0093] (b) When hour

[0094]

[0095] (c) When hour

[0096]

[0097] (d) When hour

[0098]

[0099] (e) When hour

[0100]

[0101] In the above formulas, the parameter ΔH = H2 - H0, and its value can be directly obtained from the digital display of the calibration device. x During the measurement process, the coordinates v of the laser centerline can be extracted. x P0, D0, P2, D2 have been obtained through calibration, ΔH x =H x -H 0, In the above formula, H x Unknown, P x unknown.

[0102] Furthermore, based on the relationship between various parameters of the camera lens, we can obtain... Figure 7 .

[0103] In the figure, W0 and W2 represent the field of view at working distances H0 and H2. β represents the vertical field of view angle of the lens.

[0104] According to the diagram, we can obtain equation (6).

[0105]

[0106] Based on this formula, two unknowns H can be established. x P x The relationship between them can be solved by combining them with equations (1) to (5) respectively, and then ΔH can be obtained in the five cases. x Z w .

[0107] During the measurement process, based on the pixel position v of the light stripe in the obtained image... xDetermine which situation it is in, and then, except for situation (c) where the result is obtained directly, all other cases require simultaneous calculation using equation (6). .

[0108] Because the plate shape detection system operates online in real time, the steel plate will vibrate during transportation, leading to significant errors in the detection results. Therefore, vibration compensation is necessary for the measurement results. The vibration is primarily vertical, so only the measured Z-axis vibration needs to be compensated. w Vibration compensation is performed using coordinates. Below is a vibration compensation method and its principle.

[0109] When the steel plate is measured at a constant speed and at equal intervals, let R1 and R2 represent two laser lines respectively. Then, the Z value calculated from the two laser lines at time t is obtained. w The value can be expressed by formulas (7) and (8).

[0110]

[0111]

[0112] Every Δt interval, the steel plate at the R2 laser line moves to the R1 position, equivalent to the laser line moving backward on the steel plate for measurement. When the measurement time interval is set to the time interval between the steel plate moving from R1 to R2, every Δt interval will cause the R1 laser line to measure the same position as the R2 laser line at the previous moment. Thus, the steel plate position measured by R2 at time t1 and the steel plate position measured by R1 at time t2 should be the same, and the results should also be the same. However, due to vibration, a deviation S1 will occur between the two, such as... Figure 8 As shown by the red dashed line.

[0113]

[0114] Therefore, the vibration magnitude S1 is added to all measurements taken at time t2 and thereafter to eliminate the vibration. Similarly, at time t... i The measurement result at position R1 at time 1 will produce an S difference compared to the measurement result at position R2 at the previous time 2. i-1 The vibration value can be positive or negative. If the first measurement position is set at R2 at time t1, then at t... i The height Z after vibration elimination when measuring the steel plate at all times. w The coordinates should be:

[0115]

[0116] S32, X on the surface of the steel plate w coordinate

[0117] The measurement system consists of multiple cameras. To complete the measurement of the entire plate shape, the 3D data calculated by each camera needs to be stitched together. During camera installation, the installation position of each camera was determined to ensure that each camera has a certain common field of view, such as... Figure 9 As shown, several calibration objects are placed on the calibration board, with each calibration object located within the common field of view of two adjacent cameras. Matching points are found using images captured by the two cameras to obtain the spatial transformation matrix. Then, utilizing the uniqueness of the world coordinate system of the calibration board with the same pose in the common field of view of adjacent cameras, the coordinate systems of multiple cameras are mapped onto the reference coordinate system. Based on the uniqueness of the actual laser plane, the coordinate systems of multiple cameras are unified to the same pose. By using the positional relationship of the point cloud data of adjacent cameras after unifying the coordinates, the point cloud data is directly stitched together based on the coordinate mapping result. This effectively avoids the large amount of computation caused by feature matching using point cloud data, and realizes the rapid stitching of point cloud data from multiple cameras.

[0118] Figure 9 In the middle, P iH P is the coordinate of the center of the marker to the right of the i-th camera. iL Let ΔL be the coordinates of the center of the marker to the left of the i-th camera. i It is the actual length of the i-th calibration object. It represents the number of pixels in the image occupied by the size of the left-hand calibration object under the i-th camera. It is the number of pixels occupied by the right-side calibration object under the i-th camera in the image. It is the actual size represented by a unit pixel of the i-th camera. According to equation (11), and substituting the working distance H of the i-th camera based on the reference plane... i We can obtain:

[0119]

[0120] ΔH i This indicates the height increase of the area during stitching. The coordinates increase sequentially to the right, starting from the first camera. Formula (12) represents the calculation of the coordinates of the 3D data of the plate shape in the width direction when there are i cameras, where... It is the image height of the nth camera.

[0121]

[0122] S33, Y on the surface of the steel plate w coordinate

[0123] Y w Based on the moving speed and time of the steel plate, starting from the running time t=0, based on the moving speed V of the steel plate... p Y w The value is:

[0124]

[0125] This invention enables three-dimensional reconstruction and shape measurement of the surface of a steel plate. To achieve high-precision detection of the plate shape, this invention uses a dual-line laser measurement system to acquire the X, Y, and Z coordinate data of the steel plate surface.

[0126] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for measuring and calibrating the shape of a steel plate, characterized in that: It includes a calibration device and a measuring device. The calibration device includes a lifting device, a fixing device, a rotating device and a calibration plate. The calibration plate is mounted on the upgrading device through the rotating device and can move with the lifting device. The upgrading device is fixed on both sides of the roller conveyor through the fixing device. The measuring device includes multiple cameras and two line lasers. All cameras are fixed on the same horizontal plane at a certain distance apart, while the two lasers are placed in parallel and spaced apart from each other. The calibration measurement process is carried out according to the following steps: S1. Place and fix the calibration device on the roller conveyor of the steel plate shape measurement system. Determine the position where the upper surface of the calibration plate is flush with the surface of the steel plate to be measured as the unique reference plane. At this time, the working distance of the camera lens is... ; S2. Lift the calibration plate using the lifting platform of the calibration device. At this altitude, the working distance of the camera lens is... Then, the working distance of the camera lens is calculated as follows: and The single pixel precision of the camera at that time Laser centerline coordinates Difference from the image height center coordinates The single pixel precision of the camera Laser centerline coordinates Difference from the image height center coordinates ; S3. A dual-line laser is used to perform three-dimensional reconstruction of the steel plate surface, and the plate shape data represents the steel plate surface in the world coordinate system. coordinate; S31, the surface of the steel plate Coordinate acquisition; Based on the calibration process and the inherent properties of the camera and lens, we obtain , , , , , and image height Image width and lens field of view During the measurement process, the working distance of the camera lens is defined as... By establishing Solving by the relationship between these parameters Z w， in ; During the measurement process, the position of the laser centerline changes depending on the height of the steel plate being measured. This situation is divided into five cases, and in each case, the principle of trigonometric similarity is used to... Establish a relationship with calibration parameters; under five different conditions, The relationship with the calibration parameters is expressed by the following formula: (a) when hour （1） (b) When hour （2） (c) When hour （3） (d) When hour （4） (e) When hour （5） In the above formulas, the parameters Its value is obtained directly from the digital display of the calibration device. During the measurement process, the coordinates of the laser centerline are extracted. get, , , , This has been obtained through calibration steps S1 and S2. In the above formula unknown, unknown; Based on the relationship between the various parameters of the camera lens, we can obtain equation (6). （6） Based on equation (6), two unknowns are established. , The relationship between them can be solved by combining them with equations (1) to (5) respectively, and then the results can be obtained in the five cases. ,Right now ; During the measurement process, the position of the light stripe pixels on the obtained image is used as a basis. Determine which situation it is in, and then, except for situation (c) where the result is obtained directly, all other cases require simultaneous calculation using equation (6). ; S32, steel plate surface coordinate; The 3D data calculated by each camera are stitched together. During camera installation, the installation position of each camera is determined so that each camera has a certain common field of view. Several calibration objects are placed on the calibration board, and each calibration object is located within the common field of view of two adjacent cameras. Matching points are found by taking pictures of two cameras to obtain the spatial transformation matrix. Then, by utilizing the uniqueness of the world coordinate system of the calibration board with the same pose in the common field of view of adjacent cameras, the coordinate systems of multiple cameras are mapped to the reference coordinate system. Based on the uniqueness of the actual laser plane, the coordinate systems of multiple cameras are unified to the same pose, and the positional relationship of the point cloud data of adjacent cameras is determined by the unified coordinates. S33, steel plate surface coordinate; Based on the moving speed and time of the steel plate, the running time Starting from the speed of the steel plate movement , The value is: 。 2. The method for measuring and calibrating the shape of a steel plate according to claim 1, characterized in that: The specific calculation process for step S2 is as follows: S21, Obtain ; Below each pair of adjacent camera views, there is a calibration object on the calibration board. The side length of the first square in the calibration object in the real world is... Then, the image is taken. Next, the program detects the corner points of the black squares and calculates the difference in the v-coordinates of the corner points in the image pixel coordinate system. In other words, the number of coordinates occupied by the side length of a square in the image pixel coordinate system allows us to obtain the single-pixel precision. ,Right now ; S22, Obtain ; First, the gray-scale centroid method in the laser centerline extraction algorithm is used to obtain... Laser centerline coordinates below Then, given the image height Its center coordinates are Therefore, we can obtain ; S23. Using the same method, the working distance can be obtained as follows: time , .

3. The method for measuring and calibrating the shape of a steel plate according to claim 2, characterized in that: The measured Z needs to be w Vibration compensation is performed using coordinates. The measurement system has two laser lines. and Then in The result was obtained from the calculation of two laser lines at a given time. The value can be expressed by formulas (7) and (8). （7） （8） When the measurement time interval is set to the steel plate from Move to At the time interval, each time This will make Laser line and the previous moment The laser line measures the same position, thus... time The measured position of the steel plate and time The steel plates at the measurement locations are in the same position, so the results should also be the same. However, due to vibration, the two results deviate by [a certain amount]. : （9） Will All measurements taken at and after that time, plus the vibration amount To eliminate vibration, and so on, in time The position measurement result compared to the previous moment The location measurement results will produce The vibration value, which can be positive or negative, is determined by setting the first measurement location as... time So, at that place, The height of the steel plate after vibration is eliminated during constant measurement. The coordinates should be: （10）。 4. The method for measuring and calibrating the shape of a steel plate according to claim 3, characterized in that: X on the surface of the steel plate w The specific calculation process for the coordinates is as follows: It is the first The center coordinates of the marker to the right of the camera. It is the first Let the center coordinates of the marker to the left of the camera be set. It is the first The actual length of the calibration object It is the first The number of pixels occupied by the left-hand marker under each camera in the image. It is the first The number of pixels occupied by the right-side calibration object in the image under each camera. It is the first The actual size represented by a unit pixel of the camera is calculated according to formula (11) and substituted into the... The working distance of each camera based on the reference plane We can obtain: （11） This indicates the elevation of the area during stitching, with the first camera as the reference, and the coordinates increasing sequentially to the right. Formula (12) represents the total elevation. When using a single camera, the coordinates of the 3D data of the plate shape in the width direction are calculated, where... It is the first Image height of each camera: 。

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