Linear position micron dimension detection device based on orthogonal CCD (Charge Coupled Device) sensor and positioning method

Abstract

The invention discloses a line position detection device based on an orthogonal CCD sensor and a positioning method. The device comprises an outer reference frame, an orthogonal CCD line target imaging module and a data acquisition and image processing unit. The orthogonal CCD line target imaging module comprises two orthogonally arranged CCD sensors, a short-distance large-wide-angle industrial camera and a calibration plate; the included angle between the optical axes of the two CCD sensors is 90 degrees, and data collection is controlled through the synchronous trigger switch. The CCD sensor realizes line target one-dimensional offset measurement under a high-precision calibration plate, realizes redundant observation of line target two-dimensional position quantity under the constraint of the orthogonal double CCD sensors and the distance between the calibration plates corresponding to the CCD sensor, and obtains a line position by using least square adjustment. According to the invention, the technical scheme of real-time calibration of the orthogonal CCD sensor and high-precision and high-reliability non-contact acquisition of the two-dimensional position of the linear target is adopted, and the problems of poor precision and low reliability of linear target measurement and extraction are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser precision three-dimensional measurement, and in particular relates to a line position detection device and a positioning method based on an orthogonal CCD sensor. Background Art

[0002] Due to the high requirements for alignment in fourth-generation light sources, researchers both domestically and internationally have considered the misalignment between the electromagnetic center and the mechanical center during alignment of particle accelerator electromagnetic devices. Consequently, several techniques for aligning particle accelerator electromagnetic devices based on electromagnetic center references have been proposed and successfully applied to fourth-generation light sources both domestically and internationally. After using a beryllium-core copper core as a reference line for high-precision calibration of electromagnetic devices, the challenge remains to accurately derive the overall linear reference for the components. While there are mature products and applications abroad, such as the binocular vision-based 3D reconstruction system developed by OSI in the United States, its accuracy is severely limited by the position parameter calibration of the binocular camera and the quality of the imaging background light, resulting in unstable and inaccurate field measurements. Furthermore, while Keyence's line target displacement sensor based on laser triangulation technology offers high accuracy, it can only provide one-dimensional directional deviation and has a limited measurement range of approximately 5 mm. Therefore, there is an urgent need to develop a high-precision two-dimensional positional deviation sensor for particle accelerator alignment measurements, with a range of at least 10 mm. Summary of the Invention

[0003] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the existing technology and provide a line position detection device and positioning method for an orthogonal CCD sensor. Through the innovative combination of orthogonal CCD imaging structure design, real-time dynamic calibration technology and redundant observation fusion algorithm, the technical problems of low precision, small range and poor environmental adaptability in the existing line position measurement technology are solved.

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

[0005] In a first aspect, the present invention provides a line position detection device based on an orthogonal CCD sensor, comprising an external reference frame, an orthogonal CCD line target imaging module, and a data acquisition and image processing unit;

[0006] The external reference frame is used to install the orthogonal CCD line target imaging module;

[0007] The orthogonal CCD line target imaging module includes two orthogonally arranged CCD sensors, a short-range and wide-angle industrial camera, a calibration plate, and an image data acquisition and control system; the optical axis angle between the two CCD sensors is 90°, and data acquisition is controlled by a synchronous trigger switch;

[0008] The image processing unit is used to collect CCD sensor data in real time, perform camera distortion correction, line target sub-pixel extraction and two-dimensional position solution;

[0009] The CCD sensor realizes one-dimensional offset measurement of the line target under the high-precision calibration plate, realizes redundant observation of the two-dimensional position of the line target under the distance constraint between the orthogonal dual CCD sensors and the calibration plates corresponding to the CCD sensors, and obtains the line position by least square adjustment.

[0010] As an optimal technical solution, the external reference frame is spherical and has a hollow accommodating space inside. One CCD sensor is arranged on the side wall of the external reference frame accommodating space, and the other CCD sensor is arranged on the bottom of the external reference frame accommodating space; there are two calibration plates, which are respectively arranged on the opposite sides of the two CCD sensors.

[0011] As an optimal technical solution, the two CCD sensors are calibrated to obtain the relative position relationship and the orientation elements in their respective cameras, obtain the position of the target ball in the current field of view and the approximate value of the global reference coordinates, inversely calculate the relative horizontal angle and vertical angle relative to the binocular vision positioning module, and pass them to the turntable drive ranging module to aim at the target ball.

[0012] As a preferred technical solution, the target ball is a homogeneous glass ball, and an embedded spherical layer is made of glass microbeads inside to achieve high-contrast reflection under the binocular vision positioning field to facilitate the determination of the pixel position of the target ball.

[0013] As a preferred technical solution, the mechanical reference surface of the external reference frame has preset flatness, parallelism and perpendicularity tolerances, and a contactable measurement reference is provided on the frame.

[0014] In a second aspect, the present invention provides a positioning method for a line position detection device based on an orthogonal CCD sensor, comprising the following steps:

[0015] S1, using a single CCD sensor to capture line target images, using a high-precision calibration plate to calibrate the camera distortion parameters in real time, and extracting the horizontal one-dimensional offset of the line target after correcting the image distortion;

[0016] S2, using two orthogonally arranged CCD sensors to synchronously capture images and combine them with the calibrated exterior orientation elements (R, t) to calculate the offset of the line target in the two-dimensional plane;

[0017] S3. Mapping the two-dimensional offset to a contactable reference of an external reference frame to achieve contactable conversion of a non-contact line target position.

[0018] As a preferred technical solution, in step S1, the camera distortion correction adopts the following model:

[0019] x"=x′·(1+k1r 2 +k2r 4 )+2p1x′y′+p2(r 2 +2x′ 2 )

[0020] y″=y′·(1+k1r 2 +k2r 4 )+2p1x′y′+p2(r 2 +2y′ 2 )

[0021] Where (x″, y″) is the corrected coordinate, k1 and k2 are radial distortion coefficients, p1 and p2 are tangential distortion coefficients, and r 2 =x′ 2 +y′ 2 , (x′, y′) is the projection coordinate of the ideal pinhole model.

[0022] As a preferred technical solution, in step S2, the exterior orientation elements (R, t) are calibrated by the following steps:

[0023] S21. Use the corner points of the calibration plate to establish the mapping relationship between the world coordinate system and the camera coordinate system:

[0024]

[0025] Where, (X, Y, Z) is the world coordinate of a point, (u, v) is the coordinate of the point projected on the image plane, in pixels; (c x ,c y ) is the reference point (usually at the center of the image); f x , f y is the focal length in pixels

[0026] S22. Solve the rotation matrix R and translation vector t through least squares adjustment.

[0027] As a preferred technical solution, in step S2, the offset of the line target in the two-dimensional plane is calculated as follows:

[0028] Use Canny operator to detect line target edges;

[0029] Calculate the sub-pixel coordinates of the edge center based on the grayscale centroid method;

[0030] The reference line is fitted using the corner points of the calibration plate, and the offset of the intersection between the line target and the reference line is calculated.

[0031] As a preferred technical solution, in step S3, the two-dimensional offset is mapped to the contactable reference of the external reference frame, specifically:

[0032] A global coordinate system is established by a spherical mirror on an external reference frame;

[0033] Use a laser tracker to measure the three-dimensional coordinates of the external reference frame;

[0034] Convert the line target offset to a space vector in the global coordinate system.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] This patent uses three core technologies: synchronous imaging of orthogonal dual CCD sensors, real-time distortion correction of high-precision calibration plates (grid tolerance ≤ 2μm), and redundant observation least squares fusion algorithm. It can achieve high-precision measurement of the two-dimensional position of line targets ≤ 5μm within a 10mm range, solving the industry pain points of the existing technology such as single measurement dimension (laser triangulation method only one dimension), poor environmental adaptability (binocular vision is interfered by light), and intangible benchmarks. At the same time, the non-contact line position is converted into a touchable physical benchmark through an external benchmark frame with an error of ≤ 4.8μm, providing a reliable domestically produced technical solution for ultra-precision measurement scenarios such as particle accelerator alignment and installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 Schematic diagram of the structure of a line position detection device of an orthogonal CCD sensor according to an embodiment of the present invention;

[0039] Figure 2 A three-dimensional rendering of an external reference frame according to an embodiment of the present invention;

[0040] Figure 3 Schematic diagram of comparison between the original image and the corrected image according to an embodiment of the present invention;

[0041] Figure 4 This is a line target extraction diagram for image processing according to an embodiment of the present invention;

[0042] Figure 5 This is a flowchart of an image processing program according to an embodiment of the present invention;

[0043] Figure 6 The figure is a flow chart of a positioning method of a line position detection device based on an orthogonal CCD sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0046] like Figure 1 As shown, the line position detection device based on the orthogonal CCD sensor of this embodiment includes an external reference frame 1, an orthogonal CCD line target imaging module and a data acquisition and image processing unit; the external reference frame is used to install the orthogonal CCD line target imaging module.

[0047] The orthogonal CCD line target imaging module includes two orthogonally arranged CCD sensors 2, a short-range and wide-angle industrial camera, and a calibration plate 3; the optical axis angle between the two CCD sensors is 90°, and data acquisition is controlled by a synchronous trigger switch;

[0048] The image processing unit is used to collect CCD sensor data in real time, perform camera distortion correction, line target sub-pixel extraction and two-dimensional position solution;

[0049] The CCD sensor realizes one-dimensional offset measurement of the line target under the high-precision calibration plate, realizes redundant observation of the two-dimensional position of the line target under the distance constraint between the orthogonal dual CCD sensors and the calibration plates corresponding to the CCD sensors, and obtains the line position by least square adjustment.

[0050] In addition, the calibration is carried out in real time during CCD image acquisition, and the external reference frame is calibrated with high precision during processing and monitoring, thus achieving contactless line target spatial position relation to the contactable reference externalization.

[0051] Understandably, while avoiding the shortcomings of similar products, this patent also aims to ensure the optimized linear position detector offers the advantage of low cost. This is because only a large amount of linear position measurement data can compensate for the shortcomings of its two-dimensional directional measurement and relatively small measuring range. Therefore, an orthogonal CCD camera is used to measure the absolute two-dimensional position of the linear target.

[0052] Since binocular vision 3D reconstruction heavily relies on the relative orientation parameters between cameras, the design proposes the requirement for the orthogonal position of the cameras. At the same time, CCD cameras are used to reduce the deformation of line target imaging. Combined with the design of the calibration substrate, the camera distortion parameter calibration and correction based on the calibration substrate are performed simultaneously during line target imaging measurement, which can greatly improve the accuracy.

[0053] Furthermore, the spatial relationship between the external reference frame and the imaging module requires strict calibration and measurement. The mechanical reference center of the imaging module and the image center of the image processing need to be aligned. However, these parameters can be determined through appropriate technical means in later calibration and testing, and the parameter accuracy is sufficiently high. The system is mainly divided into three modules, as follows:

[0054] (1) External reference frame;

[0055] like Figure 2 As shown, the external reference frame is spherical with a hollow interior. One CCD sensor is mounted on the sidewall of the external reference frame's housing, and the other is mounted on the bottom. Two calibration plates are installed, one on opposite sides of the two CCD sensors. The external reference frame is subject to stringent tolerance requirements during precision machining. It provides redundant observation conditions for the measurement data from the dual CCD sensors and successfully transfers the non-contact linear target position relationship to a tangible physical reference, ensuring both reliable and scalable measurement results.

[0056] The external reference frame is a crucial medium for converting the positional relationship of a non-contact linear target acquired by a linear position detector into a tangible physical reference. Therefore, in mechanical design, strict requirements are placed on the external reference frame's various reference surfaces, their own flatness, and their relative parallelism and perpendicularity.

[0057] At the same time, in order to meet the compatibility of the line position detector system, various types of benchmarks are arranged on the external benchmark frame, such as the benchmark surface suitable for high-precision three-dimensional coordinate machine measurement, the circular pentahedral glass bead reflective patch for high-precision close-range photogrammetry, and the high-precision spherical outer contour concentric with the spherical reflector of the laser tracker.

[0058] It is understandable that in addition to the high-precision machining tolerance requirements of the external frame benchmark, the overall system is specially designed with corresponding tooling (including lifting platforms and gantries, etc.) to strictly calibrate and check the overall accuracy of the device.

[0059] (2) Orthogonal CCD line target imaging module;

[0060] After calibration, the two CCD sensors obtain the relative position relationship and the orientation elements within each camera, obtain the position of the target ball in the current field of view and the approximate value of the global reference coordinates, inversely calculate the relative horizontal angle and vertical angle relative to the binocular vision positioning module, and pass them to the turntable drive ranging module to aim at the target ball.

[0061] The target ball is a homogeneous glass ball, and an embedded spherical layer is made of glass microbeads inside to achieve high-contrast reflection under the binocular vision positioning field, which facilitates the determination of the pixel position of the target ball.

[0062] The orthogonal CCD line target imaging module is the core part, which requires taking into account the mechanical processing and installation adjustment of the camera orthogonality, as well as the subsequent calibration and correction of the CCD camera position parameters.

[0063] Understandably, the CCD camera selection involved maintaining a certain distance between the calibration plate and the linear target during design to ensure the system's range of 10mm or more. This resulted in a large depth of field relative to the CCD camera. In the experiment, the CCD focused on the calibration plate, while the linear target imaged as a virtual image. However, the fixed calibration plate and camera positions ensured stable camera focus and imaging, as well as high precision in subsequent calibration corrections. The virtual image of the linear target can be optimized by minimizing distortion and maintaining a strictly fixed focus distance.

[0064] (3) Data acquisition and image processing unit;

[0065] The data acquisition and image processing unit of the present invention is mainly used to calibrate camera distortion and correct photos in real time, extract sub-pixels of line-type target images, and perform two-dimensional fusion.

[0066] The calibration and real-time correction of CCD cameras are both solved using existing mature image processing toolkit functions, and the processing results are good. Therefore, the fundamental problem is the extraction and fusion of the center of the line target image.

[0067] The general process for extracting the center of a line target in an image is as follows: First, the center of the line target image and the corner points in the calibration plate image are extracted. Next, a straight line is fitted from each row of corner points and intersected with the line target line to obtain the intersection point. Finally, the deviations along the horizontal and vertical calibration plate along the line and the coordinates of the intersection points on the horizontal and vertical line targets obtained in the previous step are combined to form a three-dimensional line.

[0068] (4) Testing and analysis;

[0069] To verify the feasibility and accuracy of the proposed line position detector optimization scheme, laboratory tests were conducted using a prototype system. This test employed a 0.1 mm diameter beryllium-core copper wire, used in vibrating wire magnetometry technology, as the target. A specially designed clamping mechanism secured the target. A high-precision three-dimensional translation stage was used to move a fixed displacement perpendicular to the target in a two-dimensional direction, and the results were compared with those measured by the line position detector.

[0070] like Figure 3 As shown in the figure, the left side shows the original horizontal and vertical images captured by the CCD, and the right side shows the corrected images after camera lens calibration. During the calibration of the linear position detector using the translation stage, the stage moves 0.5 mm in each horizontal and vertical direction. After stabilization, the linear position detector images are acquired and the corresponding deviation values ​​are obtained.

[0071] The comparison results show that there is a certain deviation between the displacement of the 3D translation stage and the deviation measured by the line position detector, which is about 0.02 mm, and is still a long way from the designed accuracy index of better than 5 microns. Later, in-depth analysis and combined with laser tracker fixed-point monitoring, it was found that the purchased domestic high-precision 3D translation stage had major problems in its own repeatability and stability, and could not meet the accuracy requirement within 10 microns. Therefore, the test process results cannot confirm the accuracy of the results of the line position detector optimization solution. However, judging from the deviation of the data, it can basically be concluded that the optimization solution is feasible, such as Figure 4 shown.

[0072] Therefore, the accuracy of the 3D translation stage will need to be improved in the future to ensure the accuracy of the testing process. At the same time, the line position detector solution requires further refinement of various process details, including the machining and manufacturing accuracy of the external reference frame, the installation and calibration accuracy of the imaging module, and the sub-pixel extraction and fusion accuracy of image processing, as shown in Table 1 below.

[0073] Table 1 Accuracy analysis of line position detector after optimization (unit: mm)

[0074]

[0075] Therefore, this patent solves the measurement instability problem caused by camera calibration errors, environmental interference, etc. in the existing technology through the triple technical means of hardware orthogonal constraints, software real-time calibration, and redundant observation fusion, and realizes micron-level line position detection.

[0076] like Figure 6 As shown, another embodiment of this embodiment provides a positioning method of a line position detection device based on an orthogonal CCD sensor, comprising the following steps:

[0077] S1, using a single CCD sensor to capture the line target image, using a high-precision calibration plate to calibrate the camera distortion parameters in real time, and extract the horizontal one-dimensional offset of the line target after correcting the image distortion;

[0078] Furthermore, in step S1, the choice of the digital camera model directly affects the final calibration result, so it is necessary to select a suitable camera model and determine the internal and external parameters. The internal parameters describe the internal optical and geometric characteristics of the camera, such as image center, focal length, lens distortion, etc.; the external parameters are the three-dimensional position and direction of the camera coordinates relative to the world coordinate system. The commonly used pinhole model ignores the thickness and distortion of the lens, so it cannot reflect the actual situation well. Therefore, based on the pinhole model, radial distortion and tangential distortion of the lens are introduced. A view is obtained by projecting the perspective transformation of a point in three-dimensional space onto the image plane, and its definition is

[0079] s·m′=A[R|t]·M′ (1)

[0080] or

[0081] Where (X, Y, Z) is the world coordinate of a point, (u, v) is the coordinate of the point projected on the image plane, in pixels; A is called the camera matrix or intrinsic parameter matrix; (c x ,c y ) is the reference point (usually at the center of the image); f x , f y is the focal length in pixels. So, if an image from a camera is upsampled or downsampled due to some factors, all these parameters (f x , f y , c x and c y ) will be scaled to the same scale. The intrinsic parameter matrix does not depend on the view of the scene and can be reused once calculated (as long as the focal length is fixed). The rotation-translation matrix [R|t] is called the extrinsic parameter matrix and is used to describe the motion of the camera relative to a fixed scene, or the rigid motion of an object around the camera. In other words, [R|t] transforms the coordinates of the point (X, Y, Z) to a coordinate system that is fixed relative to the camera. The transformation of equation (2) is equivalent to the form of equation (3), that is,

[0082]

[0083] A real lens is deformable, mainly including radial deformation and slight tangential deformation, so the model of formula (3) can be expanded to:

[0084]

[0085] Among them, k1 and k2 are radial deformation coefficients, and p1 and p2 are tangential deformation coefficients. The deformation coefficients do not depend on the shooting scene or the resolution of the captured image.

[0086] S2, using two orthogonally arranged CCD sensors to synchronously capture images and combine them with the calibrated exterior orientation elements (R, t) to calculate the offset of the line target in the two-dimensional plane;

[0087] Furthermore, step S2 is specifically as follows:

[0088] According to step S1, the two CCD sensor images obtained in horizontal and vertical orthogonal relation and their distortion correction are combined, as shown in FIG. Figure 3 shown.

[0089] Using MATLAB's image processing toolkit, real-time camera distortion correction is incorporated into images captured by the CCD sensor. Furthermore, by installing dual CCD sensors to ensure strict orthogonal positioning, the exterior orientation elements of the dual CCD sensors are rigorously calibrated using a high-precision calibration plate. Through simple synchronous triggering, the CCD sensor data is simultaneously extracted and combined with the exterior orientation elements to obtain the two-dimensional offset of the line target.

[0090] like Figure 4 As shown in the figure, the final horizontal and vertical orthogonal CCD sensor obtains the line target and calibration plate extraction results; Among them, the image straight line target extraction process flow Figure 5 As shown, specifically:

[0091] Use Canny operator to detect line target edges;

[0092] Calculate the sub-pixel coordinates of the edge center based on the grayscale centroid method;

[0093] The reference line is fitted using the corner points of the calibration plate, and the offset of the intersection point between the line target and the reference line is calculated.

[0094] S3. Mapping the two-dimensional offset to a contactable reference of an external reference frame to achieve contactable conversion of a non-contact line target position.

[0095] Furthermore, in step S3, the two-dimensional offset is mapped to the contactable reference of the external reference frame, specifically:

[0096] A global coordinate system is established by a spherical mirror on an external reference frame;

[0097] Use a laser tracker to measure the three-dimensional coordinates of the external reference frame;

[0098] Convert the line target offset to a space vector in the global coordinate system.

[0099] In this patent, dimensional tolerances are strictly controlled through precision machining of the device's external reference frame. After the industrial camera and high-precision calibration plate are installed, overall precision measurement and calibration are required, including precise measurement and verification of the relative positional relationships between the device's external frame reference, the camera, and the calibration plate. While achieving redundant measurement of the line target's two-dimensional offset observations, the spatial positional relationship of the line target is converted to the external reference, achieving contact-to-contact conversion of non-contact target measurement.

[0100] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A line position detection device based on an orthogonal CCD sensor, characterized in that: It includes an external reference frame, an orthogonal CCD line target imaging module, and a data acquisition and image processing unit; The external reference frame is used to install the orthogonal CCD line target imaging module; The orthogonal CCD line target imaging module includes two orthogonally arranged CCD sensors, a short-range and wide-angle industrial camera, and a calibration plate; the optical axis angle between the two CCD sensors is 90°, and data acquisition is controlled by a synchronous trigger switch; The image processing unit is used to collect CCD sensor data in real time, perform camera distortion correction, line target sub-pixel extraction and two-dimensional position solution; The CCD sensor realizes one-dimensional offset measurement of the line target under the high-precision calibration plate, realizes redundant observation of the two-dimensional position of the line target under the distance constraint between the orthogonal dual CCD sensors and the calibration plates corresponding to the CCD sensors, and obtains the line position by least square adjustment.

2. The line position detection device based on the orthogonal CCD sensor according to claim 1, characterized in that: The external reference frame is spherical and has a hollow accommodating space inside. One CCD sensor is arranged on the side wall of the external reference frame accommodating space, and the other CCD sensor is arranged on the bottom of the external reference frame accommodating space; there are two calibration plates, which are respectively arranged on the opposite sides of the two CCD sensors.

3. The line position detection device based on the orthogonal CCD sensor according to claim 1, characterized in that: After calibration, the two CCD sensors obtain the relative position relationship and the orientation elements within each camera, obtain the position of the target ball in the current field of view and the approximate value of the global reference coordinates, inversely calculate the relative horizontal angle and vertical angle relative to the binocular vision positioning module, and pass them to the turntable drive ranging module to aim at the target ball.

4. The line position detection device based on the orthogonal CCD sensor according to claim 3, characterized in that: The target ball is a homogeneous glass ball, and an embedded spherical layer is made of glass microbeads inside to achieve high-contrast reflection under the binocular vision positioning field, which facilitates the determination of the pixel position of the target ball.

5. The line position detection device based on the orthogonal CCD sensor according to claim 1, characterized in that: The mechanical reference surface of the external reference frame has preset flatness, parallelism and verticality tolerances, and a contactable measurement reference is provided on the frame.

6. The positioning method of the line position detection device based on the orthogonal CCD sensor according to any one of claims 1 to 5, characterized in that: The steps include: S1, using a single CCD sensor to capture line target images, using a high-precision calibration plate to calibrate the camera distortion parameters in real time, and extracting the horizontal one-dimensional offset of the line target after correcting the image distortion; S2, using two orthogonally arranged CCD sensors to synchronously capture images and combine them with the calibrated exterior orientation elements (R, t) to calculate the offset of the line target in the two-dimensional plane; S3. Mapping the two-dimensional offset to a contactable reference of an external reference frame to achieve contactable conversion of a non-contact line target position.

7. The positioning method of the line position detection device based on the orthogonal CCD sensor according to claim 6, characterized in that: In step S1, the camera distortion correction adopts the following model: x"=′·(1+k1r 2 +k2r 4 )+2p1x′y'+p2(r 2 +2x′ 2 ) y"=y′′·(1+k1r 2 +k2r 4 )+2p1x'y'+p2(r 2 +2y′ 2 ) Where (x″, yv) is the corrected coordinate, k1 and k2 are radial distortion coefficients, p1 and p2 are tangential distortion coefficients, and r 2 =x′ 2 +y′ 2 , (x′, y′) is the projection coordinate of the ideal pinhole model.

8. The positioning method of the line position detection device based on the orthogonal CCD sensor according to claim 6, characterized in that: In step S2, the exterior orientation elements (R, t) are calibrated by the following steps: S21. Use the corner points of the calibration plate to establish the mapping relationship between the world coordinate system and the camera coordinate system: Where, (X, Y, Z) is the world coordinate of a point, (u, v) is the coordinate of the point projected on the image plane, in pixels; (c x ,c y ) is the reference point (usually at the center of the image); f x , f y is the focal length in pixels S22. Solve the rotation matrix R and translation vector t through least squares adjustment.

9. The positioning method of the line position detection device based on the orthogonal CCD sensor according to claim 6, characterized in that: In step S2, the offset of the line target in the two-dimensional plane is calculated, specifically: Use Canny operator to detect line target edges; Calculate the sub-pixel coordinates of the edge center based on the grayscale centroid method; The reference line is fitted using the corner points of the calibration plate, and the offset of the intersection between the line target and the reference line is calculated.

10. The positioning method of the line position detection device based on the orthogonal CCD sensor according to claim 6, characterized in that: In step S3, the two-dimensional offset is mapped to the contactable reference of the external reference frame, specifically: A global coordinate system is established by a spherical mirror on an external reference frame; Use a laser tracker to measure the three-dimensional coordinates of the external reference frame; Convert the line target offset to a space vector in the global coordinate system.

Images