Automatic calibration device and method for optical tracking three-dimensional scanning system

Abstract

The invention relates to an automatic calibration device and method for an optical tracking three-dimensional scanning system, and the device comprises a calibration rod which is disposed on an A double-shaft holder and is used for calibrating a tracker; the calibration rod is used for calibrating the scanner; the biaxial holder B is used for arranging a tracker; the A double-shaft holder is reused after calibrating the tracker, and a scanner is arranged; the computer is in signal connection with the two biaxial holders to control rotation, and the computer is further connected with the tracker and the scanner through data lines or wireless hotspots and used for controlling the whole calibration process and storing and processing image data; automatic change of multiple postures in the calibration process is achieved through the double-shaft holder, automatic adjustment of multiple working distances is achieved through the electric trolley, the whole calibration process is automatically completed under control of a computer, and the calibration device has the advantages of being full-automatic in calibration process, good in calibration result precision, high in speed and free of manual intervention; the calibration precision and efficiency are improved, and the problems that a traditional manual calibration method is time-consuming, labor-consuming and insufficient in precision are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical three-dimensional scanning, and particularly relates to an automatic calibration device and method for an optical tracking three-dimensional scanning system. Background Art

[0002] Optical tracking three-dimensional scanning systems have the advantages of non-contact, high precision, and large range. They have emerged in industries such as industrial inspection, reverse design, and medical measurement, demonstrating great technological advancement.

[0003] The calibration of optical tracking three-dimensional scanning systems is very complex and involves three types of calibrations: the parameters of the tracker camera, the parameters of the scanner camera, and the coordinate system relationship between the two. The traditional method is to manually complete the three calibrations separately, usually by manually holding a calibration board or calibration rod and taking hundreds of photos at different working distances and postures. This is not only very time-consuming and laborious but also often leads to calibration failures or low precision due to inaccurate operations, seriously affecting the popularization and application of such technologies.

[0004] The patent application with the publication number CN109000582B discloses a scanning method, system, storage medium, and device for a tracking three-dimensional scanning device. The patent application mainly discloses the scanning method and the method of coordinate system conversion calibration, and does not introduce the tracking three-dimensional scanning device in detail. Moreover, the disclosed device cannot achieve automatic multi-posture shooting and long-distance movement. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an automatic calibration device and method for an optical tracking three-dimensional scanning system. By using a two-axis pan-tilt as a rotating device to achieve multiple shooting postures and an electric trolley to achieve large-range distance movement, the calibration of the coordinate relationship between the scanner and the tracker is finally realized, with the advantages of a fully automatic calibration process, good calibration result accuracy, high speed, and no need for manual intervention.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] An automatic calibration device for an optical tracking three-dimensional scanning system, comprising:

[0008] A calibration rod 1 for calibrating the tracker 3, and the calibration rod 1 is arranged on a two-axis pan-tilt A 1-1;

[0010] A calibration board 2 for calibrating the scanner 4,

[0011] A two-axis pan-tilt B 3-1, and the tracker 3 is arranged on the two-axis pan-tilt B 3-1;

[0012] After the two-axis pan-tilt A 1-1 calibrates the tracker 3, it is reused, and the scanner 4 is further arranged on the two-axis pan-tilt A 1-1;

[0013] A computer 5 is signal - connected to two two - axis pan - tilt units to control rotation. The computer 5 is also connected to a tracker 3 and a scanner 4 through a data line or a wireless hotspot, and is used to control the entire calibration process and store and process image data.

[0014] The A two - axis pan - tilt unit 1 - 1, the B two - axis pan - tilt unit 3 - 1, and the calibration board 2 are all supported by a tripod 6.

[0015] A plurality of circular marking points are attached to the surface of the calibration rod 1 and the calibration board 2.

[0016] The calibration rod 1 and the A two - axis pan - tilt unit 1 - 1 are arranged on an electric trolley 7; the multiplexed A two - axis pan - tilt unit 1 - 1 and the scanner 4 are arranged on the electric trolley.

[0017] A calibration method for the above - mentioned automatic calibration device of an optical tracking three - dimensional scanning system includes the following steps:

[0018] (1) Calibration of the tracker 3: Install the tracker 3 on the B two - axis pan - tilt unit 3 - 1. The computer 5 controls the B two - axis pan - tilt unit 3 - 1 to perform attitude changes at multiple angles, and at the same time controls the tracker 3 to take pictures at each attitude; then control the A two - axis pan - tilt unit 1 - 1 to change the angle, and repeat the above process; repeat the above steps at multiple working distances to obtain a large number of photos of the calibration rod 1, and calculate the internal and external parameters of the tracker 3 through a stereo vision algorithm.

[0019] (2) Calibration of the scanner 4: Install the scanner 4 on the multiplexed A two - axis pan - tilt unit 1 - 1. The computer 5 controls the A two - axis pan - tilt unit 1 - 1 of the scanner 4 to perform attitude changes at multiple angles, and take pictures of the calibration board 2 at each attitude, and repeat the above process; repeat the above steps at multiple working distances, and calculate the internal and external parameters of the scanner 4 through the collected photos of the calibration board 2.

[0020] (3) Calibration of the coordinate system relationship: Place the scanner 4 and the calibration board 2 within the working range of the tracker 3 at the same time. The computer 5 controls the A two - axis pan - tilt unit 1 - 1 of the scanner 4 to change multiple poses. At each pose, control the tracker 3 to take pictures of the scanner 4 and the calibration board 2 at the same time, and the scanner 4 to take pictures of the calibration board 2. Calculate the transformation relationship matrix between the coordinate system of the tracker 3 and the coordinate system of the scanner 4 through two groups of photos to complete the calibration of the coordinate system relationship between the tracker 3 and the scanner 4.

[0021] The automatic control at multiple working distances in step (1) is achieved by arranging the calibration rod 1 and the A two-axis pan-tilt 1-1 on the electric vehicle 7. The automatic control at multiple working distances in step (2) is achieved by arranging the scanner 4 and the reused A two-axis pan-tilt 1-1 on the electric vehicle 7. The electric vehicle 7 is controlled by the computer 5 to travel.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The automatic change of multiple postures during the calibration process is realized through two two-axis pan-tilts. (2)

[0024] Through the arrangement of the electric vehicle, the multi-working distance is changed from manual adjustment to automatic

[0025] adjustment.

[0026] (3) The computer controls the two-axis pan-tilt, the calibration rod, the calibration rod plate, and the electric vehicle, realizing the full automation of the entire calibration process.

[0027] In summary, the present invention realizes the automatic change of multiple postures during the calibration process through the two-axis pan-tilt, realizes the automatic adjustment of multiple working distances through the electric vehicle, and the entire calibration process is automatically completed under the control of the computer. It has the advantages of full automation of the calibration process, good accuracy of the calibration result, high speed, and no need for manual intervention, greatly reducing manual operation, improving the calibration accuracy and efficiency, and solving the problems of time-consuming, laborious, and insufficient accuracy of the traditional manual calibration method. Description of the Drawings

[0028] Figure 1 is the overall schematic diagram of the automatic calibration device of the present invention.

[0029] Figure 2 is the overall schematic diagram of the automatic calibration device with an electric vehicle of the present invention. Detailed Embodiments

[0030] The present invention will be further described below with reference to the drawings:

[0031] Refer to Figure 1 , an automatic calibration device for an optical tracking three-dimensional scanning system, comprising:

[0032] A calibration rod 1 for calibrating the tracker 3, and the calibration rod 1 is arranged on the A two-axis pan-tilt 1-1.

[0034] A calibration plate 2 for calibrating the scanner 4;

[0035] After the A two-axis pan-tilt 1-1 calibrates the tracker 3, the scanner 4 is further arranged on the A two-axis pan-tilt 1-1.

[0036] A computer 5 is signal-connected to two two-axis pan-tilt heads to control rotation. The computer 5 is also connected to a tracker 3 and a scanner 4 through a data cable or a wireless hotspot, and is used to control the entire calibration process and store and process image data.

[0037] The A two-axis pan-tilt head 1-1, the B two-axis pan-tilt head 3-1 and the calibration board 2 are all supported by a tripod 6.

[0038] A plurality of circular marking points are pasted on the surface of the calibration rod 1 and the calibration board 2.

[0039] Refer to Figure 2 , the calibration rod 1 and the A two-axis pan-tilt head 1-1 are arranged on an electric vehicle 7, and the multiplexed A two-axis pan-tilt head 1-1 and the scanner 4 are arranged on the electric vehicle 7. The electric vehicle 7 is automatically moved to different positions by a computer to realize a more automated calibration process, and improve the calibration efficiency and accuracy.

[0040] The tracker 3 is composed of a binocular or multiocular stereo vision system.

[0041] The scanner 4 is composed of binocular or multiocular stereo vision and a laser structured light projector, and a plurality of circular marking points are pasted on its outer surface.

[0042] A calibration method for an automatic calibration device of the above optical tracking three-dimensional scanning system includes the following steps:

[0043] (1) Calibration of the tracker 3: The tracker 3 is installed on the B two-axis pan-tilt head 3-1, and the calibration rod 1 is installed on the A two-axis pan-tilt head 1-1. The two two-axis pan-tilt heads are respectively supported by a tripod 6. The computer 5 controls the B two-axis pan-tilt head 3-1 to perform attitude changes at multiple angles, and simultaneously controls the tracker 3 to take pictures at each attitude; then controls the A two-axis pan-tilt head 1-1 to change the angle, and repeats the above process; repeats the above steps at multiple working distances, obtains a large number of pictures of the calibration rod 1, and calculates the internal and external parameters of the tracker 3 through a stereo vision algorithm.

[0044] (2) Calibration of the scanner 4: The scanner 4 is installed on the multiplexed A two-axis pan-tilt head 1-1. The computer 5 controls the A two-axis pan-tilt head 1-1 of the scanner 4 to perform attitude changes at multiple angles, and takes pictures of the calibration board 2 at each attitude, and repeats the above process; repeats the above steps at multiple working distances, and calculates the internal and external parameters of the scanner 4 through the collected pictures of the calibration board 2.

[0045] (3) Coordinate system relationship calibration: Place the scanner 4 and the calibration plate 2 within the working range of the tracker 3 simultaneously. The computer 5 controls the A two-axis gimbal 1-1 of the scanner 4 to change multiple poses. At each pose, the computer 5 controls the tracker 3 to capture the scanner 4 and the calibration plate 2 simultaneously, and the scanner 4 captures the calibration plate 2. The transformation relationship matrix between the coordinate system of the tracker 3 and the coordinate system of the scanner 4 is calculated through two sets of photos, completing the calibration of the coordinate system relationship between the tracker 3 and the scanner 4.

[0046] The automatic control at multiple working distances in step (1) is achieved by setting the calibration rod 1 and the two-axis gimbal 1-1 on the electric trolley 7, and the electric trolley 7 controls its travel through the computer 5.

[0047] Step (1) is specifically as follows:

[0048] When calibrating the tracker 3, the computer 5 is connected to the tracker 3, the A two-axis gimbal 1-1, and the B two-axis gimbal 3-1 through a data cable or a wireless hotspot respectively; the calibration rod 1 is placed within the working distance range of the tracker 3; starting from the closest distance, the computer 5 sends commands to the A two-axis gimbal 1-1 to control the two rotation axes of the A two-axis gimbal 1-1 to change N poses in space. At each pose, the computer 5 sends commands to notify the tracker 3 to take pictures. After completing the pictures of N poses, the computer 5 sends commands to the B two-axis gimbal 3-1 to control the B two-axis gimbal 3-1 to change an angle, so that the tracker 3 can capture the calibration rod 1 at another position in the captured image. Then the computer 5 controls the two-axis gimbal 1-1 to repeat the change of N poses and take pictures, and then the computer 5 controls the B two-axis gimbal 3-1 to change an angle again and repeat the shooting of N poses. This cycle is repeated until a total of M tracker gimbal pose changes are completed. N pictures are taken at each pose, and a total of the first group of M*N pictures are taken; then, move the calibration rod 1 to a farther distance and repeat the above steps to complete the shooting of the second group of M*N pictures; according to the need, complete the shooting at the remaining working distances. There are a total of L working distances, and M*L*N pictures are taken. These pictures are saved by the computer 5 for stereo vision camera calibration calculation to obtain the internal and external parameters of the tracker 3.

[0049] Step (2) is specifically as follows:

[0050] When calibrating the scanner 4, the computer 5 is connected to the scanner 4, the reused A two-axis gimbal 1-1 through a data cable or a wireless hotspot. The scanner 4 and the calibration plate 2 are adjusted to the same height through the tripod 6, and the distance between them is kept within the working distance of the scanner 4; the computer 5 controls the A two-axis gimbal 1-1 to change multiple poses, and at each pose, the computer 5 controls the scanner 4 to take pictures of the calibration plate 2, completes the saving of multiple pictures, and obtains the internal and external parameters of the scanner 4 through calculation.

[0051] The specific content of step (3) is as follows:

[0052] The computer 5 is connected to the tracker 3, the scanner 4, the B two-axis pan-tilt 3-1, and the multiplexed A two-axis pan-tilt 1-1 through a data cable or a wireless hotspot. The scanner 4 and the calibration board 2 are adjusted to the same height, and the distance between the scanner 4 and the calibration board 2 is kept within the working distance of the scanner 4. The scanner 4 and the calibration board 2 are placed within the working range of the tracker 3 at the same time so that the tracker can capture the scanner and the calibration board at the same time. The computer 5 controls the multiplexed A two-axis pan-tilt 1-1 to change multiple poses. At each pose, the tracker 3 captures photos of the marker points on the scanner 4 and the calibration board 2, and at the same time the scanner 4 captures the marker points on the calibration board 2. The conversion relationship matrix between the coordinate system of the tracker 3 and the coordinate system of the scanner 4 is obtained through calculation of the two sets of photos, and the calibration of the coordinate system relationship between the tracker 3 and the scanner 4 is completed.

[0053] See Figure 2 , this structure, compared with Figure 1 the scheme, replaces the process of manually moving the calibration rod with the automatic movement of the electric trolley 7, realizing a higher degree of automation in the calibration process.

[0054] That is to say, the automatic control at multiple working distances in step (2) is realized by arranging the scanner 4 and the multiplexed A two-axis pan-tilt 1-1 on the electric trolley 7, and the electric trolley 7 controls its travel through the computer 5.

[0055] The calibration rod 1 or the scanner 4 is installed on the electric trolley 7, and the computer 5 controls the trolley to automatically move to different positions, realizing a more automated calibration process and improving the calibration efficiency and accuracy.

[0056] In this calibration mode with a trolley, when calibrating the tracking instrument 3, the electric trolley 7 is placed within the working distance of the tracking instrument 3. The computer 5 controls the tracking instrument 3 to capture photos of the calibration rod 1 on the electric trolley 7, calculates the current specific position coordinates of the calibration rod 1 within the field of view of the tracking instrument, and then the computer 5 sends the specified position coordinates to the electric trolley 7. The electric trolley 7 transports the calibration rod 1 to the specified position. The computer 5 sends commands to the A two-axis pan-tilt head 1-1 of the calibration rod 1, controlling the two rotating axes of the A two-axis pan-tilt head 1-1 to change N postures in space. At each posture, the computer 5 sends commands to notify the tracking instrument 3 to take photos. After completing the photo-taking of N postures; the computer 5 sends commands to the B two-axis pan-tilt head 3-1, controlling the B two-axis pan-tilt head 3-1 to change by an angle, so that the tracking instrument 3 can capture the calibration rod 1 at another position in the captured image. Then the computer 5 controls the A two-axis pan-tilt head 1-1 to repeat the change of N postures and take photos, and then the computer controls the B two-axis pan-tilt head 3-1 to change by an angle again and repeat the photo-taking of N postures. In this way, a cycle is completed, and a total of M tracking instrument pan-tilt head posture changes are completed. N photos are taken at each posture, and a total of the first group of M*N photos are taken; Next, the computer 5 sends the next specified position coordinates to the electric trolley 7, and the electric trolley 7 transports the calibration rod 1 to the specified position; repeat the above steps to complete the photo-taking of the second group of M*N; complete the photo-taking of the remaining specified positions as needed, with a total of L working distances, and M*L*N photos are taken. These photos are saved by the computer and used for stereo vision camera calibration calculation to obtain the internal and external parameters of the tracking instrument 3.

[0057] In this calibration mode with a trolley, the scanner can be installed on the electric trolley 7, and the computer controls the trolley to move to the next specified position to collect calibration data at different positions through the automatic movement of the trolley.

[0058] When calibrating the coordinate system relationship between the tracking instrument and the scanner, the scanner and the calibration board need to be placed within the working range of the tracking instrument at the same time, so that the tracking instrument can capture the marker points on the scanner and the calibration board at the same time. The computer controls the scanner pan-tilt head to change multiple poses. At each pose, the tracking instrument takes photos of the marker points on the scanner and the calibration board, and at the same time the scanner takes photos of the marker points on the calibration board. Through these two groups of photos, the transformation relationship matrix between the tracking instrument coordinate system and the scanner coordinate system is calculated to complete the calibration of the coordinate system relationship between the two.

[0059] The present invention realizes the automatic change of multiple postures during the calibration process through the two-axis pan-tilt head, and realizes the automatic adjustment of multiple working distances through the electric trolley. The entire calibration process is automatically completed under the control of the computer, greatly reducing manual operations, improving the calibration accuracy and efficiency, and solving the problems of time-consuming, laborious and insufficient accuracy of traditional manual calibration methods.

Claims

1. An automatic calibration device for an optical tracking three-dimensional scanning system, characterized in that Comprising: A calibration rod (1) for calibrating a tracker (3), the calibration rod (1) being arranged on a double-axis pan-tilt head A (1-1). A calibration plate (2) for calibrating a scanner (4); A double-axis pan-tilt head B (3-1), with a tracker (3) arranged on the double-axis pan-tilt head B (3-1); After the double-axis pan-tilt head A (1-1) calibrates the tracker (3), it is reused, and a scanner (4) is further arranged on the double-axis pan-tilt head A (1-1); A computer (5), which is signal-connected to the two double-axis pan-tilt heads to control rotation, and the computer (5) is also connected to the tracker (3) and the scanner (4) through a data line or a wireless hotspot, for controlling the entire calibration process and storing and processing image data.

2. The automatic calibration device of an optical tracking three-dimensional scanning system according to claim 1, wherein The double-axis pan-tilt head A (1-1), the double-axis pan-tilt head B (3-1) and the calibration plate (2) are all supported by a tripod (6).

3. The automatic calibration device of an optical tracking three-dimensional scanning system according to claim 1, characterized in that, A plurality of circular marking points are attached to the surfaces of the calibration rod (1) and the calibration plate (2).

4. The automatic calibration device of an optical tracking three-dimensional scanning system according to claim 1, characterized in that, The calibration rod (1) and the double-axis pan-tilt head (1-1) are arranged on an electric trolley (7); the reused double-axis pan-tilt head A (1-1) and the scanner (4) are arranged on the electric trolley (7).

5. A calibration method for an automatic calibration device of an optical tracking three-dimensional scanning system according to any one of claims 1-4, characterized in that, Including the following steps: (1) Calibration of the tracker (3): Install the tracker (3) on the double-axis pan-tilt head B (3-1), the computer (5) controls the double-axis pan-tilt head B (3-1) to perform attitude changes at multiple angles, and at the same time controls the tracker (3) to take pictures at each attitude; then control the double-axis pan-tilt head A (1-1) to change the angle, and repeat the above process; repeat the above steps at multiple working distances, obtain a large number of photos of the calibration rod (1), and calculate the internal and external parameters of the tracker (3) through a stereo vision algorithm; (2) Calibration of the scanner (4): Install the scanner (4) on the reused double-axis pan-tilt head A (1-1), the computer (5) controls the double-axis pan-tilt head A (1-1) of the scanner (4) to perform attitude changes at multiple angles, and take pictures of the calibration plate (2) at each attitude, and repeat the above process; repeat the above steps at multiple working distances, and calculate the internal and external parameters of the scanner (4) through the collected photos of the calibration plate (2); (3) Calibration of the coordinate system relationship: Place the scanner (4) and the calibration plate (2) within the working range of the tracker (3) at the same time, the computer (5) controls the double-axis pan-tilt head A (1-1) of the scanner (4) to change multiple poses, and at each pose, simultaneously control the tracker (3) to photograph the scanner (4) and the calibration plate (2), and the scanner (4) to photograph the calibration plate (2), and calculate the transformation relationship matrix between the coordinate system of the tracker (3) and the coordinate system of the scanner (4) through the two groups of photos, and complete the calibration of the coordinate system relationship between the tracker (3) and the scanner (4).

6. The calibration method according to claim 5, wherein The automatic control at multiple working distances in step (1) is realized by arranging the calibration rod (1) and the double-axis pan-tilt head A (1-1) on the electric trolley (7), and the automatic control at multiple working distances in step (2) is realized by arranging the scanner (4) and the reused double-axis pan-tilt head A (1-1) on the electric trolley (7), and the electric trolley (7) is controlled by the computer (5) for its travel.

7. The calibration method according to claim 5, characterized in that, The specific content of step (1) is as follows: When calibrating the tracker (3), the computer (5) is respectively connected to the tracker (3), the A two-axis pan-tilt (1-1), and the B two-axis pan-tilt (3-1) through a data cable or a wireless hotspot; the calibration rod (1) is placed within the working distance range of the tracker (3); starting from the closest distance, the computer (5) sends commands to the A two-axis pan-tilt (1-1) to control the two rotation axes of the A two-axis pan-tilt (1-1) to change N postures in space. At each posture, the computer (5) sends commands to notify the tracker (3) to take pictures. After completing the picture-taking of N postures, the computer (5) sends commands to the B two-axis pan-tilt (3-1) to control the B two-axis pan-tilt (3-1) to change by an angle, so that the tracker (3) can take pictures of the calibration rod (1) at another position in the captured image. Then, the computer (5) controls the two-axis pan-tilt (1-1) to repeat the change of N postures and take pictures. Next, the computer (5) controls the B two-axis pan-tilt (3-1) to change by an angle again and repeats the picture-taking of N postures. This cycle continues until a total of M tracker pan-tilt posture changes are completed. N pictures are taken at each posture, and a total of the first group of M*N pictures are taken; then, the calibration rod (1) is moved to a farther distance, and the above steps are repeated to complete the picture-taking of the second group of M*N; according to the need, the picture-taking at the remaining working distances is completed. There are a total of L working distances, and M*L*N pictures are taken. These pictures are saved by the computer (5) and used for the camera calibration calculation of stereo vision to obtain the internal and external parameters of the tracker (3).

8. The calibration method according to claim 5, wherein The specific content of step (1) is as follows: The specific content of step (2) is as follows: When calibrating the scanner (4), the computer (5) is connected to the scanner (4) through a data cable or a wireless hotspot. The reused A two-axis pan-tilt (1-1), the scanner (4), and the calibration board (2) are adjusted to the same height through the tripod (6), and the distance between them is kept within the working distance of the scanner (4); the computer (5) controls the reused A two-axis pan-tilt (1-1) to change multiple postures, and at each posture, the computer (5) controls the scanner (4) to take pictures of the calibration board (2), and after completing the saving of multiple pictures, the internal and external parameters of the scanner (4) are obtained through calculation.

9. The calibration method according to claim 5, characterized in that The specific content of step (1) is as follows: The specific content of step (3) is as follows: The computer (5) is connected to the tracker (3), the scanner (4), the B two-axis gimbal (3-1) and the multiplexed A two-axis gimbal (1-1) through a data cable or a wireless hotspot. The scanner (4) and the calibration board (2) are adjusted to the same height, and the distance between the scanner (4) and the calibration board (2) is maintained within the working distance of the scanner (4). The scanner (4) and the calibration board (2) are simultaneously placed within the working range of the tracker (3) so that the tracker can simultaneously capture the scanner and the calibration board. The computer (5) controls the multiplexed A two-axis gimbal (1-1) to change multiple poses. At each pose, the tracker (3) captures photos of the marker points on the scanner (4) and the calibration board (2), and at the same time, the scanner (4) captures the marker points on the calibration board (2). Through calculation of the two groups of photos, the transformation relation matrix between the coordinate system of the tracker (3) and the coordinate system of the scanner (4) is obtained, and the calibration of the coordinate system relationship between the tracker (3) and the scanner (4) is completed.

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