Scanning system, calibration device and calibration method of scanning system

Abstract

The present invention relates to the field of digital measurement technology, and discloses a scanning system, a calibration device for the scanning system, and a calibration method. The scanning system includes a laser scanning head and a binocular tracker, wherein the laser scanning head is configured to detect the surface of a part to be measured placed in a tracking area; a plurality of binocular trackers are provided, the tracking fields of the plurality of binocular trackers are adjacent, and the sum of the tracking fields of the plurality of trackers covers the tracking area; the binocular trackers are configured to track the laser scanning head, and the coordinate information of the laser scanning head acquired by the plurality of binocular trackers is based on a tracking coordinate system. The present invention effectively increases the tracking area by providing a plurality of binocular trackers with adjacent tracking fields of view; the plurality of binocular trackers are based on a tracking coordinate system, and the accumulated error in coordinate conversion between the plurality of traditional binocular trackers is eliminated, and the conversion accuracy between the binocular trackers is effectively improved, which is conducive to ensuring the reliability of the measurement data.

Description

Technical Field

[0001] The present invention relates to the field of digital measurement technology, and in particular to a scanning system, a calibration device and a calibration method for the scanning system. Background Art

[0002] In the appearance inspection of aircraft parts and components, laser scanners are often used to obtain dense point cloud data for quality analysis or reverse engineering. In laser scanning equipment, there are two types: point scanning and tracking scanning. The point-based positioning scanning method requires a large number of highlight marks to be arranged on the surface of the object to be measured for overall splicing of the scanning results. This method will cause a lot of point-pasting and point-tearing work, and the labor cost is relatively high. The tracking scanning method uses laser tracking technology or photogrammetry technology as a tracker to locate the position and posture of the laser scanning probe in real time. The scanning probe then obtains the point cloud data on the surface of the object through laser triangulation, and combines all the data into a whole. This method does not require point-pasting to obtain complete point cloud data. However, due to the influence of factors such as camera resolution and image distortion in photogrammetry technology, the tracking range of the tracker's tracking scanner is greatly limited, and the tracking range is generally no more than 16m3. At the same time, the joint use of multiple trackers can effectively increase the overall tracking range, but since the initial coordinate system of each tracker is different, it is necessary to unify the coordinate system of the device coordinate systems of multiple trackers.

[0003] In the prior art, the coordinate system of multiple trackers also needs to arrange multiple groups of highlight marks in the measured space, and use the commonly recognized marks to connect the adjacent trackers to the coordinate system, which also involves a lot of sticking and tearing work. In addition, the traditional coordinate system of multiple trackers needs to arrange multiple marks in the space for station transfer. In order to improve the accuracy of station transfer, two-thirds of the space between adjacent trackers needs to overlap, which greatly reduces the measurement range when used in combination. And when multiple trackers are used in the coordinate system, each device will accumulate a station transfer error when the coordinate system is used. This error will gradually accumulate when transferring and splicing between different stations. After accumulation, it will cause a larger error and reduce the reliability of the measurement data.

[0004] Therefore, there is an urgent need for a scanning system, a calibration device and a calibration method for the scanning system to solve the above problems. Summary of the invention

[0005] Based on the above, an object of the present invention is to provide a scanning system, a calibration device and a calibration method for the scanning system, which have a large tracking area and reliable measurement data.

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

[0007] A scanning system comprising:

[0008] A laser scanning head, wherein the laser scanning head is configured to detect a surface of a part to be detected placed in a tracking area;

[0009] There are multiple binocular trackers, the tracking fields of the multiple binocular trackers are adjacent, the sum of the tracking fields of the multiple trackers covers the tracking area, the binocular trackers are configured to track the laser scanning head, and the coordinate information of the laser scanning head obtained by the multiple binocular trackers is based on the tracking coordinate system.

[0010] A scanning system calibration device, used for calibrating the scanning system as described above, the scanning system calibration device comprising:

[0011] A laser tracker, wherein the coordinate system of the laser tracker is the tracking coordinate system;

[0012] The calibration component is used to assist in calibrating the binocular tracker, calibrate the binocular tracker and the laser scanning head, and calibrate the binocular tracker and the laser tracker.

[0013] As a preferred solution of a calibration device for a scanning system, the calibration component includes a calibration plate and a reflection component arranged on the calibration plate.

[0014] As a preferred solution of the calibration device of a scanning system, a plurality of marking points are arranged on the calibration plate, and the marking points are used to reflect the incident light back to the light source along the original path.

[0015] As a preferred solution of the calibration device of a scanning system, it also includes a planar base, which is arranged on the calibration plate, and the reflection component is detachably arranged on the planar base.

[0016] As a preferred solution of a calibration device for a scanning system, the reflection component includes a visual reflection component and a laser reflection component.

[0017] As a preferred solution for the calibration device of a scanning system, the laser reflector includes a spherical seat and three mutually perpendicular reflective mirrors arranged in the spherical seat, and the reflected light reflected by the three reflective mirrors is parallel to the incident light and offset by a preset distance.

[0018] A scanning system calibration method is used to calibrate the scanning system as described above, and the calibration steps are as follows:

[0019] Acquire an original reference file of the coordinates of the marker points and the reflective component on the calibration plate placed within the tracking field of view of the binocular tracker;

[0020] Acquire the coordinate file of the marking points and the reflective component on the calibration plate of the tracking field of view through a laser tracker, and obtain the conversion matrix between the original reference file and the coordinate file;

[0021] The calibration plates are placed in the tracking fields of the remaining binocular trackers in sequence, and the conversion matrices of the remaining binocular trackers and the laser tracker are obtained in sequence.

[0022] As a preferred solution of a calibration method for a scanning system, the step of obtaining the original reference file and obtaining the conversion matrix further includes replacing the visual reflective element with a laser reflective element.

[0023] As a preferred solution of a calibration method for a scanning system, before acquiring the original reference file through the binocular tracker, it also includes calibrating the binocular tracker.

[0024] The beneficial effects of the present invention are:

[0025] The scanning system of the present invention is used to detect the surface of the part to be measured in the tracking area by setting a laser scanning head. There is no need to arrange highlight mark points on the surface of the part to be measured, which reduces a lot of point sticking and tearing work, has lower labor costs and higher detection efficiency; by setting up multiple binocular trackers with adjacent tracking fields, there is no need to consider the overlapping range between adjacent binocular trackers, and the tracking area is effectively increased; at the same time, the coordinate information of the laser scanning heads obtained by the multiple binocular trackers is based on the tracking coordinate system. By establishing the tracking coordinate system, each binocular tracker is independently aligned with the tracking coordinate system covering the entire tracking area, thereby eliminating the cumulative error in coordinate conversion between multiple traditional binocular trackers, effectively improving the conversion accuracy between binocular trackers, and helping to ensure the reliability of measurement data.

[0026] The calibration device of the scanning system is used to realize the coordinate system unity between multiple binocular trackers by setting up a laser tracker. Since the coordinate system of the laser tracker is a tracking coordinate system, the transformation matrix of each binocular tracker based on the tracking coordinate system can be obtained by calibrating each binocular tracker with the laser tracker. Then, when the laser scanning head is tracked by the binocular tracker, a unified coordinate based on the tracking coordinate system can be obtained. The conversion accuracy is high and the cumulative error is small, which ensures the reliability of the measurement data. At the same time, the setting of the calibration component is used to assist in the calibration of the binocular tracker, the laser scanning head and the laser tracker.

[0027] The calibration method of the scanning system is convenient to calibrate, has low labor cost, reliable calibration results and small errors. The scanning system calibrated by the calibration method has a unified coordinate system, and the conversion accuracy of multiple binocular trackers is high, and the measurement data is reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. 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 the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0029] Figure 1 is a schematic diagram of a scanning system provided by a specific embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of a calibration device for a scanning system provided in a specific embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of a calibration component of a calibration device for a scanning system provided in a specific embodiment of the present invention.

[0032] In the figure:

[0033] 1. Laser scanning head; 2. Binocular tracker; 3. Laser tracker; 4. Calibration component; 41. Calibration plate; 411. Marking point; 42. Reflection component; 43. Plane base. DETAILED DESCRIPTION

[0034] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of 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.

[0035] like Figure 1 As shown, this embodiment provides a scanning system, which includes a laser scanning head 1 and a binocular tracker 2. The laser scanning head 1 is configured to detect the surface of a part to be measured placed in a tracking area; a plurality of binocular trackers 2 are provided, the tracking fields of the plurality of binocular trackers 2 are adjacent, and the sum of the tracking fields of the plurality of trackers covers the tracking area. The binocular tracker 2 is configured to track the laser scanning head 1, and the coordinate information of the laser scanning head 1 obtained by the plurality of binocular trackers 2 is based on a tracking coordinate system.

[0036] By setting a laser scanning head 1, it is used to realize the detection of the surface of the part to be measured in the tracking area. There is no need to arrange highlight mark points 411 on the surface of the part to be measured, which reduces a lot of point sticking and tearing work, reduces labor costs and improves detection efficiency; by setting multiple binocular trackers 2 with adjacent tracking fields, there is no need to consider the overlapping range between adjacent binocular trackers 2, which effectively increases the tracking area; at the same time, the coordinate information of the laser scanning head 1 obtained by the multiple binocular trackers 2 is based on the tracking coordinate system. By establishing the tracking coordinate system, each binocular tracker 2 is independently aligned with the tracking coordinate system covering the entire tracking area, eliminating the cumulative error during coordinate conversion between multiple traditional binocular trackers 2, effectively improving the conversion accuracy between the binocular trackers 2, and helping to ensure the reliability of the measurement data.

[0037] Specifically, the binocular tracker 2 is a device used to obtain the image of the photographed object (laser scanning head 1) in real time. The binocular tracker 2 is mainly composed of a camera, a lens and a light source. By solving the 2D photos obtained by photogrammetry, the high-precision 3D coordinate value of the measurement point is obtained. The laser scanning head 1 is the end effector of laser data acquisition. The marker point 411 containing high-reflectivity glass beads is arranged on the actuator. The position information of the laser scanning head 1 is fed back in real time through the binocular tracker 2. The laser scanning head 1 obtains the shape data of the part to be measured through the triangulation laser principle. Through the posture information of the laser scanning head 1 fed back by the binocular tracker 2, each piece of point cloud data of the part to be measured is converted and spliced ​​into a whole.

[0038] For example, there are four binocular trackers 2, which are evenly spaced along a straight line. The tracking field of each binocular tracker 2 is 16m3, so the tracking area covered by the four binocular trackers 2 is 64m3. 3 , you can achieve 64m 3 The surface of the part to be tested within the tracking area is inspected.

[0039] like Figure 2 As shown, the present embodiment also discloses a calibration device for a scanning system, which is used to calibrate the scanning system as described above. The calibration device for the scanning system includes a laser tracker 3 and a calibration component 4. The coordinate system in which the laser tracker 3 is located is a tracking coordinate system. The calibration component 4 is used to assist in calibrating the binocular tracker 2, calibrate the binocular tracker 2 and the laser scanning head 1, and calibrate the binocular tracker 2 and the laser tracker 3.

[0040] By setting up a laser tracker 3, a coordinate system is realized between multiple binocular trackers 2. Since the coordinate system in which the laser tracker 3 is located is a tracking coordinate system, the transformation matrix of each binocular tracker 2 based on the tracking coordinate system can be obtained by calibrating each binocular tracker 2 with the laser tracker 3. Then, when the laser scanning head 1 is tracked by the binocular tracker 2, a unified coordinate based on the tracking coordinate system can be obtained. The conversion accuracy is high and the cumulative error is small, thereby ensuring the reliability of the measurement data. At the same time, the calibration component 4 is set to assist in calibrating the binocular tracker 2, the laser scanning head 1 and the laser tracker 3.

[0041] Specifically, the laser tracker 3 is a computer-aided measurement system that uses two angle encoders and a laser interferometer to measure horizontal angles, vertical angles and distances, and then calculates X, Y and Z coordinates, which can achieve coordinate unification between multiple binocular trackers 2.

[0042] like Figure 3 As shown, in this embodiment, the calibration component 4 includes a calibration plate 41 and a reflection component 42 arranged on the calibration plate 41. The calibration plate 41 is set in the corresponding tracking field of view, and then the emission status of the reflection component 42 is obtained by the binocular tracker 2 and the laser tracker 3 for calibration.

[0043] Furthermore, a plurality of marking points 411 are provided on the calibration plate 41. During the calibration process, the marking points 411 are used to reflect the incident light back to the light source along the original path, and are used to assist in calibrating the binocular tracker 2, the binocular tracker 2 and the laser scanning head 1, and the binocular tracker 2 and the laser tracker 3. Exemplarily, the marking points 411 are made of a material containing high-reflectivity glass beads or microcrystalline cubic corner bodies, which reflects the incident light back to the light source along the original path to form a retro-reflective material.

[0044] Preferably, the calibration device of the scanning system further includes a plane base 43, the plane base 43 is arranged on the calibration plate 41, and the reflective assembly 42 is detachably arranged on the plane base 43, so as to facilitate the selection of a suitable reflective assembly 42 according to the instrument to be calibrated, and improve the replacement efficiency of the reflective assembly 42. Exemplarily, the plane base 43 is provided with magnetism, so as to facilitate the disassembly and installation of the reflective assembly 42, and the connection is convenient and reliable.

[0045] In this embodiment, the reflective assembly 42 includes a visual reflector and a laser reflector, wherein the visual reflector is used for calibrating the binocular tracker 2, specifically a reflective target seat for obtaining hole position information of the measured object, and is also an important converter for performing reference conversion with the laser tracker 3. The laser reflector includes a ball seat and three mutually perpendicular reflectors arranged in the ball seat, and the reflected light reflected by the three reflectors is parallel to the incident light and offset by a preset distance, and is used for calibrating the binocular tracker 2 and the laser tracker 3.

[0046] This embodiment also discloses a calibration method for a scanning system, wherein the scanning system is calibrated by the calibration device of the scanning system, and the calibration steps are as follows:

[0047] S10, using a binocular tracker 2 to obtain an original reference file of the coordinates of the marker points 411 and the reflective component 42 on the calibration plate 41 placed within its tracking field of view.

[0048] Specifically, at least three plane bases 43 are arranged on the calibration plate 41, which are not on the same straight line, preferably four plane bases 43 are arranged, and the four plane bases 43 are respectively located at the four corners of the calibration plate 41, denoted as T1-T4; at this time, visual reflectors are placed on the plane bases 43. In addition, nine marking points 411 are also arranged on the calibration plate 41, denoted as P1-P9; T1-T4 and P1-P9 at at least two positions are assigned values ​​by the binocular tracker 2 as original reference files.

[0049] It is worth noting that the original reference file can not only display the coordinates of the marking point 411 and the reflective component 42 , but also display the relative positions of the marking point 411 and the reflective component 42 on the calibration plate 41 .

[0050] Preferably, the binocular tracker 2 continuously measures P1-P9 and T1-T4 on multiple groups of calibration plates 41, and uses the average value of the multiple groups of data as the measured value of the marker point 411 and the reflective component 42 at the position to ensure the accuracy of the original reference file. Exemplarily, the binocular tracker 2 continuously measures ten groups of data and calculates the average value of the ten groups of data.

[0051] After the original reference file is obtained, the visual reflector is replaced with a laser reflector to facilitate the subsequent calibration of the laser tracker 3 .

[0052] S20, obtaining the coordinate file of the marking point 411 and the reflective component 42 on the calibration plate 41 of the tracking field of view through the laser tracker 3, and converting the original reference file into a conversion matrix of the coordinate file.

[0053] Specifically, the laser tracker 3 obtains the coordinate values ​​of the laser reflector T1-T4 on the calibration plate 41 at that position. Since the replaced laser reflector has the same position as the visual reflector, the coordinate values ​​of the visual reflector T1-T4 obtained by the binocular tracker 2 in S10 are fitted to the coordinate values ​​of the laser reflector T1-T4 obtained by the laser tracker 3 to obtain the conversion matrix of the binocular tracker 2 and the laser tracker 3, thereby realizing the calibration of the binocular tracker 2 and the laser tracker 3.

[0054] Preferably, to ensure the accuracy of calibration, after S20, the calibration plate 41 is also changed so that the calibration plate 41 can cover the tracking field of view of the binocular tracker 2. After changing the position of the calibration plate 41, the binocular tracker 2 obtains the coordinate values ​​of the marker points 411P1-P9 at the position, and the laser tracker 3 obtains the coordinate values ​​of the laser reflector T1-T4 at the position. Since the relative positions of the marker points 411 and the reflector assembly 42 on the calibration plate 41 have been obtained in S10, the coordinate values ​​of the laser reflector T1-T4 at the position can be calculated by the coordinate values ​​of the marker points 411P1-P9 obtained by the binocular tracker 2, and then the calculated coordinate values ​​of the laser reflector T1-T4 are fitted to the coordinate values ​​of the laser reflector T1-T4 obtained by the laser tracker 3 at the position, so as to obtain the conversion matrix at the position; and then the conversion matrices at the two positions are fitted and aligned, so as to obtain a more accurate conversion matrix of the binocular tracker 2 and the laser tracker 3.

[0055] S30, placing the calibration plate 41 in the tracking field of view of the remaining binocular trackers 2 in sequence, and obtaining the conversion matrix of the remaining binocular trackers 2 and the laser tracker 3 in sequence.

[0056] Specifically, the step S20 is used to calibrate each binocular tracker 2 and the laser tracker 3, that is, the coordinates obtained by each binocular tracker 2 are aligned to the tracking coordinate system where the laser tracker 3 is located, thereby achieving the unification of the coordinates of multiple binocular trackers 2.

[0057] It is worth noting that, during the processes of S20 and S30 , the position of the laser tracker 3 cannot be moved to ensure the stability and uniqueness of the tracking coordinate system.

[0058] Before obtaining the original reference file through the binocular tracker 2 in S10 , the binocular tracker 2 is also calibrated.

[0059] After the calibration is completed, the parts to be measured can be inspected by the laser scanning head 1. At the same time, the laser scanning head 1 is tracked by multiple binocular trackers 2. The positions and postures of the laser scanning head 1 obtained by the multiple binocular trackers 2 are all based on the tracking coordinate system, and the tracking area is large, so the measurement data is reliable.

[0060] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

[0061] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0062] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A calibration device for a scanning system, characterized in that: Used for calibrating a scanning system, the scanning system comprising: A laser scanning head (1), wherein the laser scanning head (1) is configured to detect a surface of a part to be detected that is placed in a tracking area; A plurality of binocular trackers (2) are provided, the tracking fields of view of the plurality of binocular trackers (2) are adjacent, the sum of the tracking fields of view of the plurality of trackers covers the tracking area, the binocular trackers (2) are configured to track the laser scanning head (1), and the coordinate information of the laser scanning head (1) acquired by the plurality of binocular trackers (2) is based on a tracking coordinate system; The calibration device of the scanning system comprises: A laser tracker (3), wherein the coordinate system in which the laser tracker (3) is located is the tracking coordinate system; A calibration component (4) is used to assist in calibrating the binocular tracker (2), calibrate the binocular tracker (2) and the laser scanning head (1), and calibrate the binocular tracker (2) and the laser tracker (3); The calibration component (4) comprises a calibration plate (41) and a reflection component (42) arranged on the calibration plate (41); The calibration plate (41) is provided with a plurality of marking points (411), and the marking points (411) are used to reflect the incident light back to the light source along the original path; It also includes a plane base (43), wherein the plane base (43) is arranged on the calibration plate (41), and the reflection component (42) is detachably arranged on the plane base (43); The reflection component (42) includes a visual reflection component and a laser reflection component; The laser reflector comprises a ball seat and three mutually perpendicular reflectors arranged in the ball seat, and the reflected light reflected by the three reflectors is parallel to the incident light and offset by a preset distance.

2. A method for calibrating a scanning system, characterized in that: Applied to calibrate the calibration device as claimed in claim 1, the calibration steps are as follows: Acquiring an original reference file of the coordinates of a marking point (411) and a reflection component (42) on a calibration plate (41) placed within the tracking field of view of the binocular tracker (2); Acquiring the coordinate file of the marking point (411) and the reflective component (42) on the calibration plate (41) of the tracking field of view through a laser tracker (3), and obtaining a conversion matrix between the original reference file and the coordinate file; The calibration plate (41) is sequentially placed in the tracking field of view of the remaining binocular trackers (2), and the conversion matrix of the remaining binocular trackers (2) and the laser tracker (3) is sequentially obtained; An original reference file of the coordinates of a marking point (411) and a reflection component (42) on a calibration plate (41) placed within the tracking field of view of the binocular tracker (2) is obtained, comprising: Using the binocular tracker (2), assigning values ​​to the plane base and the marking points at at least two positions as original reference files; The laser tracker (3) is used to obtain the coordinate file of the marking point (411) and the reflective component (42) on the calibration plate (41) of the tracking field of view, and obtain a conversion matrix between the original reference file and the coordinate file, including: Fitting the coordinate values ​​of the plane base of the visual reflector obtained by the binocular tracker (2) to the coordinate values ​​of the plane base of the laser reflector obtained by the laser tracker (3) to obtain a conversion matrix of the laser tracker (3); The coordinate value of the plane base of the laser reflector at the corresponding position is obtained by using the coordinate value of the plane base of the marking point obtained by the binocular tracker (2); Fitting the coordinate values ​​of the plane base of the laser reflector to the coordinate values ​​of the plane base of the laser reflector obtained by the laser tracker (3) at the corresponding position to obtain a conversion matrix at the corresponding position; Fitting and aligning the conversion matrix of the laser tracker (3) with the obtained conversion matrix at the corresponding position, so as to optimize the conversion matrix of the binocular tracker (2) and the laser tracker (3); The process between obtaining the original reference file and obtaining the conversion matrix further includes replacing the visual reflective element with a laser reflective element, wherein the replaced laser reflective element has the same position as the visual reflective element; The laser tracker (3) obtains the coordinate values ​​of the plane base of the laser reflector on the calibration plate (41) at the position, so as to fit the coordinate values ​​of the plane base of the visual reflector obtained by the binocular tracker (2) to the coordinate values ​​of the plane base of the laser reflector obtained by the laser tracker (3), thereby obtaining a conversion matrix of the laser tracker (3).

3. The calibration method of the scanning system according to claim 2, characterized in that: Before acquiring the original reference file through the binocular tracker (2), the method further includes calibrating the binocular tracker (2).

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