Five-axis CCD calibration method, system, device and storage medium

Abstract

The present invention belongs to the field of visual inspection technology and specifically discloses a five-axis CCD calibration method, system, device and storage medium. The method comprises the following steps: obtaining an image set of a calibration plate captured by a CCD camera at a corresponding rotation angle and performing grayscale processing; extracting calibration points and determining corresponding pixel coordinates and world coordinates; calculating camera parameters based on the calibration point pixel coordinates and world coordinates, performing corresponding calibration and correction, and obtaining a corrected image; selecting a target point through the corrected image and determining the coordinates of the target point's center; and finally, calculating the world coordinates of the center point of a five-axis turntable using the coordinates of the three target points' centers according to a three-point cocircularity method. This method can achieve efficient calibration of the center of a five-axis turntable. The present invention can make the calibration operation of a five-axis turntable more convenient, effectively reduce calibration errors, and improve calibration accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of visual detection technology, and in particular relates to a five-axis CCD calibration method, system, equipment and storage medium. Background Art

[0002] The five-axis turntable equipment is a non-standard custom-made device that includes three linear servo axes and two rotary servo axes. The equipment has a high degree of precision, so the calibration accuracy requirements for the equipment are also very high. Currently, the common centralized five-axis turntable calibration methods are: 1. Manual calibration of the five-axis turntable center; 2. Direct measurement method; 3. Measurement method using a laser sensor. These common calibration methods have the following defects in actual application: 1. Measurement errors are very likely to occur; 2. Some parameters in the measurement process cannot be obtained through direct measurement, such as the coordinate system between the linear axis and the rotary axis, the relative position relationship of distant points, etc.; 3. Parameters obtained by direct measurement are prone to errors, affecting the calibration accuracy, and laser measurement is easily blocked and has poor anti-pollution properties, making measurement not very convenient. Therefore, there is an urgent need for a calibration method that is more efficient, easier to operate, and has higher calibration accuracy. Summary of the Invention

[0003] The purpose of the present invention is to provide a five-axis CCD calibration method, system, device and storage medium to solve the above-mentioned problems existing in the prior art.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, a five-axis CCD calibration method is provided, comprising:

[0006] Acquire an image set of a calibration plate captured by a CCD camera at corresponding rotation angles, the image set comprising a plurality of calibration plate images, the calibration plate being fixed on a five-axis turntable, the rotation angle of which is controlled by the five-axis turntable, and the CCD camera being mounted on one rotation axis of the five-axis turntable facing the calibration plate for capturing images;

[0007] Grayscale processing is performed on each calibration plate image in the image set to obtain a corresponding black and white image, wherein the black and white image contains a number of calibration points on the calibration plate;

[0008] Extract each calibration point from the black and white image and determine the pixel coordinates and world coordinates of each calibration point;

[0009] Calculate the intrinsic and extrinsic parameters of the CCD camera based on the pixel coordinates and world coordinates of each calibration point;

[0010] Each black and white image is corrected using the internal and external parameters of the CCD camera to obtain the corresponding corrected image;

[0011] Select the point in the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, and calculate the average coordinates based on the world coordinates of the center of each circle, and use the average coordinates as the center coordinates of the target point;

[0012] The center coordinates of the three target points are determined according to the image sets of the calibration plate at three rotation angles, and the world coordinates of the center point of the five-axis turntable are calculated using the center coordinates of the three target points.

[0013] In one possible design, the method further includes: after the five-axis turntable rotates several times and multiple center point world coordinates are calculated, determining the optimal center point world coordinates using a least squares method based on the multiple center point world coordinates.

[0014] In one possible design, the five-axis turntable includes three linear axes and two rotational axes. The three linear axes are X-axis, Y-axis and Z-axis, and the two rotational axes are A-axis and C-axis. The CCD camera is installed on the C-axis. The A-axis of the five-axis turntable rotates a set angle each time, and the C-axis rotates a corresponding angle in an incremental manner. After each rotation, the CCD camera takes several calibration plate images to form a corresponding image set.

[0015] In one possible design, grayscale processing is performed on each calibration plate image in the image set to obtain a corresponding black and white image, including:

[0016] Grayscale processing is performed on each calibration plate image in the image set so that the grayscale value of each pixel in the calibration plate image is 0 or 255, and the grayscale value of the pixel within the calibration point range is different from the grayscale value of the pixel within the calibration plate background range.

[0017] In one possible design, the calculation of the intrinsic and extrinsic parameters of the CCD camera based on the pixel coordinates and world coordinates of each calibration point includes:

[0018] According to the pixel coordinates and world coordinates of each calibration point, the Zhang Youzheng calibration method is used to calculate the intrinsic and extrinsic parameters of the CCD camera.

[0019] In one possible design, the internal parameters include focal length, pixel size, and distortion coefficient, and the external parameters include position parameters and posture parameters.

[0020] In a possible design, the world coordinates of the center point of the five-axis turntable are calculated using the coordinates of the center points of the three target points, including:

[0021] According to the constraints that the coordinates of the three target points’ centers are coplanar and the distances from the three target points’ centers to the center of the space circle are equal, the world coordinates of the center of the space circle are calculated by combining the coordinates of the three target points’ centers.

[0022] The world coordinates of the center of the space circle are used as the world coordinates of the center point of the five-axis turntable.

[0023] In a second aspect, a five-axis CCD calibration system is provided, comprising an acquisition unit, an ashing unit, an extraction unit, a first calculation unit, a correction unit, a determination unit, and a second calculation unit, wherein:

[0024] an acquisition unit, configured to acquire an image set of a calibration plate captured by a CCD camera at a corresponding rotation angle, the image set comprising a plurality of images of the calibration plate, the calibration plate being fixed on a five-axis turntable, the rotation angle of which is controlled by the five-axis turntable, and the CCD camera being mounted on a rotation axis of the five-axis turntable to capture the calibration plate;

[0025] a graying unit, configured to grayscale each calibration plate image in the image set to obtain a corresponding black-and-white image, wherein the black-and-white image includes a number of calibration points on the calibration plate;

[0026] An extraction unit, used to extract each calibration point from the black and white image and determine the pixel coordinates and world coordinates of each calibration point;

[0027] A first calculation unit is used to calculate the intrinsic parameters and extrinsic parameters of the CCD camera according to the pixel coordinates and world coordinates of each calibration point;

[0028] A correction unit, used to correct each black and white image using the internal and external parameters of the CCD camera to obtain a corresponding corrected image;

[0029] a determination unit, configured to select the point at the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, calculate the average coordinates based on the world coordinates of the centers of the circles, and use the average coordinates as the center coordinates of the target point;

[0030] The second calculation unit is used to determine the coordinates of the center of three target points according to the image sets of the calibration plate at three rotation angles, and calculate the world coordinates of the center point of the five-axis turntable using the coordinates of the center of the three target points.

[0031] In a third aspect, a five-axis CCD calibration device is provided, comprising:

[0032] a memory for storing instructions;

[0033] A processor is used to read the instructions stored in the memory and execute any one of the methods described in the first aspect according to the instructions.

[0034] In a fourth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform any one of the methods described in the first aspect. Also provided is a computer program product containing the instructions that, when executed on a computer, cause the computer to perform any one of the methods described in the first aspect.

[0035] Beneficial effects: The present invention performs grayscale processing on an image set of a calibration plate taken by a CCD camera at a corresponding rotation angle; then extracts the calibration points and determines the corresponding pixel coordinates and world coordinates; then calculates the camera parameters based on the pixel coordinates and world coordinates of the calibration points, performs corresponding calibration and correction, and obtains a corrected image; selects a target point through the corrected image and determines the coordinates of the center of the target point; finally, according to the three-point cocircular method, the world coordinates of the center point of the five-axis turntable are calculated using the coordinates of the centers of the three target points, thereby realizing efficient calibration of the center of the five-axis turntable. The present invention can replace the traditional five-axis turntable calibration method, making the calibration operation of the five-axis turntable more convenient, effectively reducing the calibration error, and improving the calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Schematic diagram of the steps of the method in Example 1 of the present invention;

[0038] Figure 2 Schematic diagram of the system structure in Example 2 of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the device in Example 3 of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that the description of these embodiments is intended to help understand the present invention, but does not constitute a limitation of the present invention. The specific structural and functional details disclosed herein are merely intended to describe exemplary embodiments of the present invention. However, the present invention may be embodied in a variety of alternative forms, and should not be construed as being limited to the embodiments set forth herein.

[0041] It should be understood that, unless otherwise specified or limited, the term "connection" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the embodiments based on specific circumstances.

[0042] In the following description, certain details are provided to facilitate a complete understanding of the example embodiments. However, one of ordinary skill in the art will appreciate that the example embodiments can be practiced without these specific details. For example, a system may be shown in a block diagram to avoid obscuring the example with unnecessary detail. In other embodiments, well-known processes, structures, and techniques may be shown without unnecessary detail to avoid obscuring the embodiment.

[0043] Example 1:

[0044] This embodiment provides a five-axis CCD calibration method, which can be applied to corresponding five-axis CCD calibration processors, such as Figure 1 As shown, the method includes the following steps:

[0045] S1. Obtain an image set of a calibration plate captured by a CCD camera at corresponding rotation angles, wherein the image set includes several images of the calibration plate. The calibration plate is fixed on a five-axis turntable, whose rotation angle is controlled by the five-axis turntable. The CCD camera is mounted on a rotation axis of the five-axis turntable and photographs the calibration plate.

[0046] In a specific implementation, a calibration plate (a standard measurement tool for visual inspection, containing several array-distributed calibration points) is fixed to a five-axis turntable. The five-axis turntable controls the corresponding rotation angle, driving the calibration plate to rotate. A CCD camera is mounted on one of the five-axis turntable's rotation axes to photograph the calibration plate. Each time the plate rotates by a corresponding angle, the CCD camera captures an image set of the calibration plate. The image set contains several calibration plate images. The five-axis turntable includes three linear axes and two rotational axes. The three linear axes are the X-axis, Y-axis, and Z-axis, and the two rotational axes are the A-axis and C-axis. The CCD camera is mounted on the C-axis. The A-axis of the five-axis turntable rotates by a set angle each time, and the C-axis rotates by a corresponding angle in increments. After each rotation, the CCD camera captures several images of the calibration plate to form a corresponding image set. For example, every time the A-axis rotates 1°, the C-axis rotates incrementally by 1° until it reaches a full 360°. The CCD camera takes a picture every 1° of rotation. The A-axis rotation angle can be set to a set number of degrees, such as 0.25° or 0.3°. The same principle applies to the C-axis: more C-axis rotations result in more samples. The difference is that the A-axis has a limited rotation position; the calibration plate must be within the CCD camera's field of view, for example, from -15° to 15°.

[0047] S2. grayscale processing is performed on each calibration plate image in the image set to obtain a corresponding black and white image, wherein the black and white image contains a number of calibration points on the calibration plate.

[0048] In specific implementation, each calibration plate image in the image set is grayscaled so that the grayscale value of each pixel in the calibration plate image is 0 or 255 (black is 0, white is 255), and the grayscale value of the pixel within the calibration point range is different from the grayscale value of the pixel within the calibration plate background range, so as to distinguish the calibration point from the calibration plate background, and obtain the corresponding black and white image containing several calibration points on the calibration plate.

[0049] S3. Extract each calibration point from the black and white image, and determine the pixel coordinates and world coordinates of each calibration point.

[0050] In specific implementation, each calibration point is extracted from the black-and-white image, the pixel coordinates of each calibration point in each black-and-white image are recorded, and the world coordinates of each calibration point in the real world are determined based on the configuration properties and rotation angles of the five-axis turntable and the calibration plate.

[0051] S4. Calculate the intrinsic and extrinsic parameters of the CCD camera based on the pixel coordinates and world coordinates of each calibration point.

[0052] In specific implementation, the Zhang Youzheng calibration method is used to calculate the internal and external parameters of the CCD camera based on the pixel coordinates and world coordinates of each calibration point. The internal parameters include focal length, pixel size and distortion coefficient, and the external parameters include position parameters and attitude parameters. The calibration principle formula of the Zhang Youzheng calibration method includes:

[0053] Convert world coordinates to pixel coordinates:

[0054]

[0055] Radial distortion correction formula:

[0056] x corr =x dis (1+k1r 2 +k2r 4 +k3r 6 )

[0057] y corr =y dis (1+k1r 2 +k2r 4 +k3r 6 )

[0058] Tangential distortion correction formula:

[0059] x corr =x dis +[2p1xy+p2(r 2 +2x 2 )]

[0060]

[0061] Combination of radial distortion and tangential distortion:

[0062]

[0063] Among them, u and v represent pixel coordinates, dX and dY represent how many mm each column and row represent, that is, the scale factors of the u axis and the v axis, and x w 、y w and z w Represents the world coordinates, f is the focal length, R is the rotation matrix, t is the offset vector, R and t constitute the position parameters and attitude parameters of the external parameters, x dis and y dis Representing the camera coordinates, r = u*u+v*v, k1, k2 and k3 are three radial distortion coefficients, and p1 and p2 are two tangential distortion coefficients.

[0064] Zhang Youzheng's calibration method is a camera calibration method based on a planar target. By taking multiple images of a calibration plate, the world coordinates of the calibration points on the calibration plate correspond one-to-one to the pixel coordinates, so as to perform a conversion between the world coordinates and the pixel coordinates. The corresponding camera parameters are obtained in the process of converting the world coordinates and the pixel coordinates.

[0065] S5. Correct each black and white image using the internal and external parameters of the CCD camera to obtain a corresponding corrected image.

[0066] In specific implementation, each black and white image can be corrected using the intrinsic and extrinsic parameters of the CCD camera, including distortion correction and position parameter adjustment, to obtain a corresponding corrected image.

[0067] S6. Select the point in the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, and calculate the average coordinates based on the world coordinates of the centers of the circles, and use the average coordinates as the center coordinates of the target point.

[0068] In specific implementation, the point in the upper left corner of each corrected image is selected as the target point, the world coordinates of the center of the target point in each corrected image are determined, and then the average value is taken to obtain the average coordinate, which is used as the coordinates of the center of the target point.

[0069] S7. Determine the coordinates of the centers of the three target points based on the image sets of the calibration plate at the three rotation angles, and use the coordinates of the centers of the three target points to calculate the world coordinates of the center point of the five-axis turntable.

[0070] In specific implementation, the coordinates of the three target points can be analyzed and determined based on the image set of the calibration plate at three rotation angles. Then, based on the constraints that the three target points' center coordinates are coplanar and the distances from the three target points' center coordinates to the center of the space circle are equal, the world coordinates of the center of the space circle are calculated in combination with the three target points' center coordinates. The implementation principle is that the coordinates of the three target points' centers are known to be (x1, y1, z1), (x2, y2, z2), and (x3, y3, z3). The coordinates and radius of the center of the space circle determined by these three points are calculated. The constraints are that the three target points' center coordinates are coplanar and the distances from the three target points' center coordinates to the center of the space circle are equal. This results in four free terms to solve four equations. The corresponding linear algebraic equations can be listed and solved using the elimination method:

[0071]

[0072] A1=y1*z2-y1*z3-z1*y2+z1*y3+y2*z3-y3*z2

[0073] B1=-x1*z2+x1*z3+z1*x2-z1*x3-x2*z3+x3*z2

[0074] C1=x1*y2-x1*y3-y1*x2+y1x3+x2y3-x3*y2

[0075] D1=-x1*y2*z3+x1*y3*z z+x2*y1*z3-x3*y1*z2-x2*y3*z1+x3*y2*z1

[0076] The coordinates of the three target points’ centers correspond to the same distance from the target points to the center of the space circle:

[0077]

[0078] From this, the world coordinates of the center of the spatial circle can be calculated and used as the world coordinates of the center point of the five-axis turntable. Furthermore, after the five-axis turntable rotates several times and multiple center point world coordinates are calculated, the least squares method can be used to determine the optimal center point world coordinate based on these multiple center point world coordinates.

[0079] CCD machine vision dimensional measurement is based on relative measurement methods, calculating actual dimensions through traceability, magnification calibration, automatic edge enhancement, and screen image measurement. For precision measurement, magnification must reach 35x or higher to achieve micron-level accuracy, at which point the line of sight is less than 5mm. For objects larger than 5mm, it must be combined with displacement analysis readings and window measurement. It can automatically measure product dimensions, using CCD cameras to capture objects from multiple angles, measuring basic values such as length, width, and height. Measurement accuracy can also be increased to 0.001mm by increasing the number of CCD cameras and adjusting the angles to meet different measurement requirements. It can also measure the dimensions of objects of various shapes simultaneously, deriving the corresponding dimensions through database calculations.

[0080] The method of this embodiment can replace the traditional five-axis turntable calibration method, making the calibration operation of the five-axis turntable more convenient, effectively reducing the calibration error, and improving the calibration accuracy.

[0081] Example 2:

[0082] This embodiment provides a five-axis CCD calibration system. Figure 2 As shown, it includes an acquisition unit, an ashing unit, an extraction unit, a first calculation unit, a correction unit, a determination unit, and a second calculation unit, wherein:

[0083] an acquisition unit, configured to acquire an image set of a calibration plate captured by a CCD camera at a corresponding rotation angle, the image set comprising a plurality of images of the calibration plate, the calibration plate being fixed on a five-axis turntable, the rotation angle of which is controlled by the five-axis turntable, and the CCD camera being mounted on a rotation axis of the five-axis turntable to capture the calibration plate;

[0084] a graying unit, configured to grayscale each calibration plate image in the image set to obtain a corresponding black-and-white image, wherein the black-and-white image includes a number of calibration points on the calibration plate;

[0085] An extraction unit, used to extract each calibration point from the black and white image and determine the pixel coordinates and world coordinates of each calibration point;

[0086] A first calculation unit is used to calculate the intrinsic parameters and extrinsic parameters of the CCD camera according to the pixel coordinates and world coordinates of each calibration point;

[0087] A correction unit, used to correct each black and white image using the internal and external parameters of the CCD camera to obtain a corresponding corrected image;

[0088] a determination unit, configured to select the point at the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, calculate the average coordinates based on the world coordinates of the centers of the circles, and use the average coordinates as the center coordinates of the target point;

[0089] The second calculation unit is used to determine the coordinates of the center of three target points according to the image sets of the calibration plate at three rotation angles, and calculate the world coordinates of the center point of the five-axis turntable using the coordinates of the center of the three target points.

[0090] Example 3:

[0091] This embodiment provides a five-axis CCD calibration device, such as Figure 3 As shown, at the hardware level, it includes:

[0092] Data interface, used to establish data connection between the processor and the CCD camera;

[0093] a memory for storing instructions;

[0094] The processor is configured to read the instructions stored in the memory and execute the five-axis CCD calibration method in Example 1 according to the instructions.

[0095] Optionally, the computer device further includes an internal bus. The processor, memory, and display may be interconnected via the internal bus, which may be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus. The bus may be divided into an address bus, a data bus, a control bus, and the like.

[0096] The memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out memory (FIFO) and / or first-in-last-out memory (FILO), etc. The processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0097] Example 4:

[0098] This embodiment provides a computer-readable storage medium having instructions stored thereon. When the instructions are executed on a computer, the computer is caused to execute the five-axis CCD calibration method of Embodiment 1. The computer-readable storage medium refers to a data storage medium, which may include, but is not limited to, a floppy disk, an optical disk, a hard disk, a flash memory, a USB flash drive, and / or a memory stick. The computer may be a general-purpose computer, a dedicated computer, a computer network, or other programmable system.

[0099] This embodiment further provides a computer program product comprising instructions, which, when executed on a computer, causes the computer to execute the five-axis CCD calibration method of embodiment 1. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable system.

[0100] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A five-axis CCD calibration method, characterized in that: include: Acquire an image set of a calibration plate captured by a CCD camera at corresponding rotation angles, the image set comprising a plurality of calibration plate images, the calibration plate being fixed on a five-axis turntable, the rotation angle of which is controlled by the five-axis turntable, and the CCD camera being mounted on one rotation axis of the five-axis turntable facing the calibration plate for capturing images; Grayscale processing is performed on each calibration plate image in the image set to obtain a corresponding black and white image, wherein the black and white image contains a number of calibration points on the calibration plate; Extract each calibration point from the black and white image and determine the pixel coordinates and world coordinates of each calibration point; Calculate the intrinsic and extrinsic parameters of the CCD camera based on the pixel coordinates and world coordinates of each calibration point; Each black and white image is corrected using the internal and external parameters of the CCD camera to obtain the corresponding corrected image; Select the point in the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, and calculate the average coordinates based on the world coordinates of the center of each circle, and use the average coordinates as the center coordinates of the target point; The center coordinates of the three target points are determined according to the image sets of the calibration plate at three rotation angles, and the world coordinates of the center point of the five-axis turntable are calculated using the center coordinates of the three target points.

2. A five-axis CCD calibration method according to claim 1, characterized in that: The method further includes: after the five-axis turntable rotates several times and multiple center point world coordinates are calculated, determining the optimal center point world coordinates based on the multiple center point world coordinates using a least squares method.

3. A five-axis CCD calibration method according to claim 1, characterized in that: The five-axis turntable includes three linear axes and two rotational axes. The three linear axes are X-axis, Y-axis and Z-axis, and the two rotational axes are A-axis and C-axis. The CCD camera is installed on the C-axis. The A-axis of the five-axis turntable rotates a set angle each time, and the C-axis rotates a corresponding angle in an incremental manner. After each rotation, the CCD camera takes several calibration plate images to form a corresponding image set.

4. A five-axis CCD calibration method according to claim 1, characterized in that: The grayscale processing of each calibration plate image in the image set to obtain a corresponding black and white image includes: Grayscale processing is performed on each calibration plate image in the image set so that the grayscale value of each pixel in the calibration plate image is 0 or 255, and the grayscale value of the pixel within the calibration point range is different from the grayscale value of the pixel within the calibration plate background range.

5. A five-axis CCD calibration method according to claim 1, characterized in that: The calculation of the intrinsic and extrinsic parameters of the CCD camera according to the pixel coordinates and world coordinates of each calibration point includes: According to the pixel coordinates and world coordinates of each calibration point, the Zhang Youzheng calibration method is used to calculate the intrinsic and extrinsic parameters of the CCD camera.

6. A five-axis CCD calibration method according to claim 5, characterized in that: The internal parameters include focal length, pixel size and distortion coefficient, and the external parameters include position parameters and posture parameters.

7. A five-axis CCD calibration method according to claim 1, characterized in that: The method of calculating the world coordinates of the center point of the five-axis turntable using the coordinates of the center of the three target points includes: According to the constraints that the coordinates of the three target points’ centers are coplanar and the distances from the three target points’ centers to the center of the space circle are equal, the world coordinates of the center of the space circle are calculated by combining the coordinates of the three target points’ centers. The world coordinates of the center of the space circle are used as the world coordinates of the center point of the five-axis turntable.

8. A five-axis CCD calibration system, characterized in that: The method comprises an acquisition unit, an ashing unit, an extraction unit, a first calculation unit, a correction unit, a determination unit, and a second calculation unit, wherein: an acquisition unit, configured to acquire an image set of a calibration plate captured by a CCD camera at a corresponding rotation angle, the image set comprising a plurality of images of the calibration plate, the calibration plate being fixed on a five-axis turntable, the rotation angle of which is controlled by the five-axis turntable, and the CCD camera being mounted on a rotation axis of the five-axis turntable to capture the calibration plate; a graying unit, configured to grayscale each calibration plate image in the image set to obtain a corresponding black-and-white image, wherein the black-and-white image includes a number of calibration points on the calibration plate; An extraction unit, used to extract each calibration point from the black and white image and determine the pixel coordinates and world coordinates of each calibration point; A first calculation unit is used to calculate the intrinsic parameters and extrinsic parameters of the CCD camera according to the pixel coordinates and world coordinates of each calibration point; A correction unit, used to correct each black and white image using the internal and external parameters of the CCD camera to obtain a corresponding corrected image; a determination unit, configured to select the point at the upper left corner of each corrected image as the target point, determine the world coordinates of the center of the target point in each corrected image, calculate the average coordinates based on the world coordinates of the centers of the circles, and use the average coordinates as the center coordinates of the target point; The second calculation unit is used to determine the coordinates of the center of three target points according to the image sets of the calibration plate at three rotation angles, and calculate the world coordinates of the center point of the five-axis turntable using the coordinates of the center of the three target points.

9. A five-axis CCD calibration device, characterized in that: include: a memory for storing instructions; A processor is used to read the instructions stored in the memory and execute the five-axis CCD calibration method according to any one of claims 1 to 7 according to the instructions.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the computer executes the five-axis CCD calibration method according to any one of claims 1 to 7.

Images