Tracking laser 3D imaging system

Abstract

This disclosure relates to a tracking laser 3D imaging system, including a laser tracker and a multi-view laser 3D scanner. The laser tracker includes: an aiming unit capable of emitting a positioning laser beam, a rotation drive mechanism for driving the aiming unit to rotate and align with the scanner, and a monocular attitude camera linked to the aiming unit. The multi-view laser 3D scanner includes: a housing, multiple retroreflectors disposed in different orientations of the housing, multiple feature marker structures arranged around the housing capable of emitting or reflecting beams, a multimode laser assembly for emitting an imaging laser beam toward the object under test, and multiple scanning imaging cameras for capturing the imaging laser beam on the object under test. Thus, the position and attitude of the multi-view laser 3D scanner can be acquired in real time by the tracker, and the point cloud data acquired by the multi-view laser 3D scanner can be unified into the coordinate system of the laser tracker.

Description

Technical Field

[0001] This disclosure relates to the field of intelligent manufacturing equipment industry, specifically to a tracking laser three-dimensional imaging system. Background Technology

[0002] A laser 3D scanner is a non-contact 3D imaging device that projects a laser onto the surface of an object and calculates its surface contour information based on the projected image. It is widely used for measuring the dimensions and shape of workpieces. However, existing laser 3D scanners have limited scanning range. When scanning large, high-end equipment such as airplanes, ships, or high-speed trains, frequent relocation is required. Traditional laser 3D scanners typically use marking points on the workpiece surface to achieve this. However, this method is not only inefficient, severely impacting scanning efficiency, but also precludes marking points on some workpieces. More importantly, this method introduces errors during relocation, and these errors accumulate gradually with repeated relocations.

[0003] Therefore, traditional laser 3D scanners are insufficient to meet the measurement needs of large, high-end equipment such as aircraft, ships, or high-speed trains. Summary of the Invention

[0004] This disclosure is made in view of the above circumstances, and its purpose is to provide a tracking laser three-dimensional imaging system capable of realizing large-scale laser scanning measurements.

[0005] Therefore, this disclosure provides a tracking laser 3D imaging system, including a laser tracker and a multi-view laser 3D scanner. The laser tracker includes: an aiming unit capable of emitting a positioning laser beam, a rotation drive mechanism for driving the aiming unit to rotate and align with the scanner, and a monocular attitude camera linked to the aiming unit. The multi-view laser 3D scanner includes: a housing, multiple retroreflectors disposed in different orientations of the housing, multiple feature marker structures arranged around the housing and capable of emitting or reflecting light beams, a multimode laser assembly for emitting an imaging laser beam toward the object under test, and multiple scanning imaging cameras for capturing the imaging laser beam on the object under test. During measurement, the aiming unit aligns with a retroreflector. The system acquires the position information of the multi-view laser 3D scanner, and the monocular attitude camera simultaneously captures multiple feature marker structures to acquire the attitude information of the multi-view laser 3D scanner. Based on the position information and the attitude information, a first transformation relationship between the feature point coordinate system and the laser tracker coordinate system is acquired. Based on the position relationship between the feature marker structure and the scanning imaging camera, a second transformation relationship between the scanning camera coordinate system and the feature point coordinate system is acquired. The imaging laser beams captured by each scanning imaging camera are matched to calculate the point cloud data of the surface of the object under test. Based on the first transformation relationship and the second transformation relationship, the point cloud data acquired by the multi-view laser 3D scanner at different positions and / or different attitudes are unified to the laser tracker coordinate system.

[0006] Because laser trackers possess high-precision spatial positioning and tracking capabilities, they can track multi-view laser 3D scanners in real time, determining the scanner's position information. Simultaneously, in conjunction with a monocular attitude camera, they can synchronously acquire the scanner's attitude information, enabling six-dimensional information measurement. Compared to typical binocular tracking devices, laser trackers offer higher measurement accuracy and significantly expand the scanner's movement range. This effectively reduces the number of station changes during the scanning of large workpieces, minimizing error introduction and improving measurement accuracy. Furthermore, the multiple retroreflectors positioned in different orientations on the multi-view laser 3D scanner ensure that when one retroreflector rotates into a blind zone, other available retroreflectors on other sides can be used to reflect and position the laser beam, achieving continuous tracking, reducing light interruptions, and improving the convenience of the measurement process. Based on this, in order to further improve the scanning accuracy, the present invention adopts a multi-eye laser 3D scanner with multiple scanning imaging cameras. By using multiple scanning imaging cameras, the depth information of the laser point can be calculated from the image positions of the same laser point on different scanning imaging cameras. This makes it more resistant to ambient light interference and more reliable, thereby realizing large-scale and high-precision laser scanning measurement.

[0007] Furthermore, in the tracking laser 3D imaging system disclosed herein, optionally, the multi-view laser 3D scanner includes four retroreflectors, which are respectively disposed on the upper side, left side, right side, and rear side of the multi-view laser 3D scanner. Therefore, even if the orientation of the multi-view laser 3D scanner changes during the scanning process, it can still reflect and position the laser beam through the retroreflectors on different sides, thereby making the multi-view laser 3D scanner more flexible during the scanning process. Additionally, in the tracking laser three-dimensional imaging system disclosed herein, optionally, a photoelectric sensor is disposed behind each retroreflector, and the retroreflector reflecting the positioning laser beam is determined based on the signal from the photoelectric sensor. Specifically, the retroreflector can be a hollow corner prism with a through hole. When the positioning laser beam is reflected by the retroreflector, a portion of the positioning laser beam can pass through the through hole and be emitted to the photoelectric sensor. When the photoelectric sensor receives the positioning laser beam, it can send information, thereby enabling the photoelectric sensor to determine the corner prism currently reflecting the positioning laser beam based on the transmitted signal.

[0008] In addition, in the tracking laser three-dimensional imaging system disclosed herein, optionally, the feature marker structure is a light source, and the retroreflector based on the reflection positioning laser beam controls the activation or deactivation of the feature marker structure on each side.

[0009] Furthermore, in the tracking laser 3D imaging system disclosed herein, optionally, the upper side, left side, right side, and rear side each include at least six of the aforementioned feature marker structures. The layout of the feature marker structures differs on different sides, and the retroreflector for reflecting and positioning the laser beam is determined based on the layout of the feature marker structures. Since the layout of the feature marker structures on each side is different, the measuring surface facing the positioning laser beam can be determined according to different layouts. Compared with the technical solution using photoelectric sensors, this reduces the size and weight of the multi-view laser 3D scanner, facilitating scanning.

[0010] Furthermore, in the tracking laser 3D imaging system disclosed herein, optionally, when the retroreflector of the laser beam being positioned is not determined, the feature marker structures on different sides are activated at different times. The feature marker structures activated when a successful match is achieved are recorded, and the retroreflector of the laser beam is determined. Then, the feature marker structures on other sides are deactivated. Since the spot image acquired by the monocular attitude camera can be used in real time for matching the feature marker structures with the spot, by sequentially activating the feature marker structures on different sides, a successful match can be achieved when the feature marker structure on the side facing the laser tracker is activated. Therefore, the side facing the laser tracker can be determined based on the feature marker structure activated when a successful match is achieved, and thus the retroreflector of the laser beam can be determined. Simultaneously, after determining the retroreflector of the laser beam, the feature marker structures on other sides can be deactivated in a timely manner, and only the feature marker structure on the alignment surface can be activated to avoid affecting the attitude measurement results.

[0011] Furthermore, in the tracking laser three-dimensional imaging system disclosed herein, optionally, four independent feature point coordinate systems are created based on the retroreflectors on different sides. During the measurement process, the corresponding feature point coordinate systems and the second transformation relationship are determined based on the retroreflectors that position the laser beam. Thus, by creating a coordinate system for each side, the position coordinates of each feature marker structure on the current side can be quickly determined, thereby enabling the rapid calculation of the second transformation relationship.

[0012] Furthermore, in the tracking laser 3D imaging system disclosed herein, optionally, among the plurality of feature marker structures located on the same side, at least two feature marker structures have lines connecting them that are parallel to the lines connecting the other two feature marker structures. Since the light spots presented by the parallel feature marker structures remain parallel during the rotation of the multi-view laser 3D scanner, by setting parallel and non-parallel feature marker structures, the light spots in the image captured by the monocular attitude camera can be quickly grouped, making it easier to subsequently determine the correspondence between the feature marker structures and the light spots.

[0013] In addition, in the tracking laser three-dimensional imaging system disclosed herein, the multi-mode laser component optionally emits line lasers, including single-line laser mode, multi-line parallel laser mode, and multi-line cross laser mode, thereby meeting different scenarios.

[0014] In addition, in the tracking laser three-dimensional imaging system disclosed herein, optionally, the multi-view laser three-dimensional scanner includes two scanning imaging cameras. During the measurement process, each laser point in the imaging laser beam captured by the two scanning imaging cameras is matched based on the epipolar geometry principle, and then the coordinates of each laser point in the scanning camera coordinate system are measured using the triangular similarity principle to form point cloud data.

[0015] Furthermore, in the tracking laser 3D imaging system disclosed herein, optionally, the multi-view laser 3D scanner transmits image information in real time, the control terminal receives the image information and matches valid image information based on the return light of the positioning laser beam, calculates point cloud data, and unifies the valid point cloud data to the coordinate system of the laser tracker. When the laser tracker can receive the returned positioning laser beam, and the returned positioning laser beam is at a preset position, it can be considered that the positioning laser beam is aligned with any retroreflector. At this time, the image information acquired by the multi-view laser 3D scanner is valid image information. Since there may be occlusion or misalignment of the positioning laser beam with the retroreflector during the scanning process of the multi-view laser 3D scanner, processing only the valid image information can avoid wasting computing power.

[0016] According to this disclosure, a tracking laser three-dimensional imaging system capable of realizing large-scale laser scanning measurement can be provided. Attached Figure Description

[0017] This disclosure will now be explained in further detail with reference to the examples in the accompanying drawings.

[0018] Figure 1 This is a schematic diagram illustrating an application scenario of the tracking laser three-dimensional imaging system involved in the examples of this disclosure.

[0019] Figure 2 This is a schematic diagram illustrating a laser tracker as described in the examples of this disclosure.

[0020] Figure 3 This is an axonometric view of the multi-view laser 3D scanner involved in the example of this disclosure.

[0021] Figure 4 This is a schematic diagram showing the left side of a multi-view laser 3D scanner as described in this disclosure example.

[0022] Figure 5 This is a schematic diagram showing the upper side of a multi-view laser 3D scanner as described in this disclosure example.

[0023] Figure 6 This is a schematic diagram showing the right side of a multi-view laser 3D scanner as described in this disclosure example.

[0024] Figure 7 This is a schematic diagram showing the rear side of a multi-view laser 3D scanner as described in this disclosure example.

[0025] Figure 8 This is a schematic flowchart illustrating the tracking laser three-dimensional imaging method involved in the example of this disclosure.

[0026] Laser tracker 1, aiming unit 11, monocular attitude camera 12, multi-view laser 3D scanner 2, retroreflector 21, feature marker structure 22, scanning imaging camera 23, multi-mode laser assembly 24, extension column 25, guide hole 251, button 26 Detailed Implementation Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same components, and repeated descriptions are omitted. Furthermore, the drawings are merely schematic diagrams, and the proportions of the components or the shapes of the components may differ from actual figures.

[0027] Furthermore, the subheadings and similar terms used in the following description of this disclosure are not intended to limit the content or scope of this disclosure; they are merely intended to serve as reading prompts. Such subheadings should not be construed as dividing the content of the article, nor should the content under a subheading be limited to the scope of that subheading.

[0028] This disclosure relates to a tracking laser 3D imaging system that achieves large-area laser scanning measurements through the cooperation of a laser tracker and a multi-view laser 3D scanner. This allows measurement results acquired by the multi-view laser 3D scanner at different positions and orientations to be unified into the coordinate system of the laser tracker.

[0029] This disclosure relates to a laser tracker having an aiming unit and a monocular attitude camera, which can be used to determine the position and attitude of a retroreflector.

[0030] This disclosure relates to a multi-view laser 3D scanner. By setting retroreflectors on the surface of the multi-view laser 3D scanner to represent position information and setting multiple feature marker structures on the surface of the multi-view laser 3D scanner to represent attitude information, the six-dimensional information of the multi-view laser 3D scanner can be determined in real time by using a laser tracker to obtain its position and attitude information.

[0031] Figure 1 This is a schematic diagram illustrating an application scenario of the tracking laser three-dimensional imaging system involved in the examples of this disclosure. Figure 2 This is a schematic diagram illustrating a laser tracker as described in the examples of this disclosure. Figure 3 This is an axonometric view of the multi-view laser 3D scanner involved in the example of this disclosure.

[0032] See Figure 1The tracking-type laser 3D imaging system includes a laser tracker 1 and a multi-view laser 3D scanner 2. Because the laser tracker 1 has high-precision spatial positioning and tracking capabilities, it can track the multi-view laser 3D scanner 2 in real time and determine its position information. Simultaneously, in conjunction with a monocular attitude camera 12, it can synchronously acquire the attitude information of the multi-view laser 3D scanner 2, thereby achieving six-dimensional information measurement of the multi-view laser 3D scanner 2. Based on the six-dimensional information of the multi-view laser 3D scanner 2, the point cloud data acquired by the multi-view laser 3D scanner 2 is unified into the coordinate system of the laser tracker. Therefore, even if the multi-view laser 3D scanner 2 moves or rotates during the scanning process, the acquired point cloud data can be unified into the same coordinate system. Compared to general binocular tracking devices, the laser tracker 1 can significantly expand the movement range of the multi-view laser 3D scanner 2, effectively reducing the number of station changes during the scanning of large workpieces, reducing the introduction of errors, and improving measurement accuracy.

[0033] See Figure 2 The laser tracker 1 may include: an aiming unit 11 capable of emitting a positioning laser beam, a rotation drive mechanism for driving the aiming unit 11 to rotate to align with the scanner, and a monocular attitude camera 12 linked to the aiming unit 11.

[0034] In some examples, the aiming unit 11 can be used to emit and receive a positioning laser beam. After the positioning laser beam is emitted, it can be reflected back to the aiming unit 11 by the retroreflector 21. The aiming unit 11 obtains the distance of the multi-view laser 3D scanner 2 based on the reflected positioning laser beam. Furthermore, the position information of the multi-view laser 3D scanner 2 is calculated by combining the distance between the multi-view laser 3D scanner 2 and the laser tracker 1 with the rotation angle of the aiming unit 11. The position information of the multi-view laser 3D scanner 2 can be represented by the spatial coordinates of the vertex of the retroreflector 21 in the coordinate system of the laser tracker.

[0035] In some examples, the aiming unit 11 can obtain the distance to the retroreflector 21 based on the principles of interferometric ranging and / or absolute ranging. The laser tracker 1 can achieve high-precision tracking over a wide range, such as high positioning accuracy at distances of 30 meters or even greater.

[0036] In some examples, the aiming unit 11 may be equipped with a position sensor, such as a PSD position detector, which can be used to detect the positioning laser beam reflected back to the aiming unit 11. When the position sensor receives the positioning laser beam, it indicates that the positioning laser beam has been reflected by the retroreflector 21. At the same time, if the spot formed by the position sensor on the positioning laser beam reflected back to the aiming unit 11 is located at a preset zero point, it can be considered that the laser beam is aligned with the retroreflector 21, and the spatial coordinates of the vertex of the retroreflector 21 can be accurately measured.

[0037] In some examples, a rotary drive mechanism can be used to drive the aiming unit 11 to rotate, so that the positioning laser beam emitted by the aiming unit 11 can have a large emission range. The rotary drive mechanism may include a first rotary mechanism and a second rotary mechanism. The first rotary mechanism can drive the aiming unit 11 to rotate along a first rotary axis, and the second rotary mechanism can drive the aiming unit 11 to rotate along a second rotary axis. The first rotary axis and the second rotary axis are not parallel, so that the aiming unit 11 can be oriented in any direction under the control of the rotary drive mechanism.

[0038] In some examples, the first rotation axis can be a horizontal rotation axis, and the first rotation mechanism can control the aiming unit 11 to rotate ±360° in the horizontal direction. In some examples, the second rotation axis can be a pitch rotation axis, and the second rotation mechanism can control the aiming unit 11 to rotate ±145° in the vertical direction.

[0039] In some examples, the rotary drive mechanism may also include only the first rotary mechanism or the second rotary mechanism, thereby enabling rotational tracking in a specific direction.

[0040] In some examples, the rotation drive mechanism can control the rotation of the aiming unit 11 in real time based on the position of the spot of the position sensor set in the aiming unit 11, until the spot of the positioning laser beam reflected back to the aiming unit 11 returns to the preset zero point, thereby enabling real-time tracking of the retroreflector 21.

[0041] See in some examples Figure 2 The laser tracker 1 also includes a monocular attitude camera 12, which can be linked with the aiming unit 11, meaning the monocular attitude camera 12 moves synchronously with the aiming unit 11. In some examples, the monocular attitude camera 12 can be housed within the aiming unit 11. Thus, whenever the aiming unit 11 is rotated, the monocular attitude camera 12 can move simultaneously in the same direction and at the same speed. In some examples, the monocular attitude camera 12 can also be independently and detachably mounted outside the aiming unit 11, for example, above or to the left or right sides of the aiming unit 11, and the monocular attitude camera 12 can be equipped with an independent drive device. In this case, the rotation of the aiming unit 11 and the monocular attitude camera 12 can be synchronously controlled by the control system.

[0042] In some examples, the central optical axis of the monocular attitude camera 12 is in the same direction as the optical axis of the laser beam, which simplifies the attitude calculation process.

[0043] In some examples, the laser tracker 1 also includes an angle measuring mechanism for obtaining the rotation angle of the aiming unit 11. In some instances, the angle measuring mechanism may be a circular grating.

[0044] In some examples, the monocular attitude camera 12 can be used to acquire positional information of the feature marker structure 22 (described later). In some examples, after the monocular attitude camera 12 captures an image, the position of the light spot in the image can be extracted; the light spot is formed by the light beam reflected or emitted by the feature marker structure 22. In some examples, after the monocular attitude camera 12 captures an image, preprocessing such as filtering and binarization can be performed, and the centroid position of the light spot can be calculated. The calculated centroid position is used to calculate the attitude information of the multi-view laser 3D scanner 2.

[0045] See in some examples Figures 3-7 The multi-view laser 3D scanner 2 may include: a housing, multiple retroreflectors 21 arranged in different orientations on the housing, multiple feature marker structures 22 arranged around the housing and capable of emitting or reflecting light beams, a multimode laser assembly 24 for emitting imaging laser beams towards the object under test, and multiple scanning imaging cameras 23 for capturing the imaging laser beams on the object under test. Thus, the position information of the multi-view laser 3D scanner 2 can be obtained by utilizing the cooperation of the retroreflectors 21 and the positioning laser beam. Furthermore, after the light beams emitted or reflected by the feature marker structures 22 are captured by the monocular attitude camera 12, six-dimensional information measurement of the multi-view laser 3D scanner 2 is achieved based on the attitude information represented by the multiple feature marker structures 22. Simultaneously, by setting multiple retroreflectors 21 in different orientations on the multi-view laser 3D scanner 2, when one retroreflector 21 rotates into a blind zone during rotation, another available retroreflector 21 can be provided to reflect the positioning laser beam, thereby achieving continuous tracking, reducing invalid scanning data, and improving the convenience of the measurement process.

[0046] See in some examples Figures 3-7 The housing of the multi-eye laser 3D scanner 2 may include multiple sides, including the front side, left side, right side, top side, rear side, and bottom side.

[0047] In some examples, retroreflectors 21 with different orientations can be positioned on different sides, allowing the laser tracker 1 to track different sides of the multi-view laser 3D scanner 2. The multi-view laser 3D scanner 2 can include multiple retroreflectors 21 with different orientations, such as 2, 3, 4, and 5. Taking a scanner with four retroreflectors 21 as an example, the four retroreflectors 21 are respectively positioned on the upper, left, right, and rear sides of the scanner. Since the front side needs to accommodate the scanning imaging camera 23 and the multi-mode laser assembly 24, it generally does not face the laser tracker 1 during scanning. Similarly, when the operator holds the multi-view laser 3D scanner 2, the lower side generally does not face the laser tracker 1. Simultaneously, the angle at which the retroreflector 21 receives the laser beam is generally within ±45°, thus ensuring that the multi-view laser 3D scanner 2 maintains a single cone reflector to position the laser beam regardless of its orientation. Therefore, positioning four retroreflectors 21 on the upper, left, right, and rear sides of the scanner can meet most measurement needs. Of course, in some special cases, retroreflectors 21 can also be positioned on the lower side.

[0048] In some examples, retroreflectors 21 with different orientations can be configured to have non-overlapping receiving angles. In other words, when the positioning laser beam is aimed at any one retroreflector 21, the other retroreflector 21 will not receive the positioning laser beam or other beams used for auxiliary positioning from the laser tracker 1. This ensures that the positioning laser beam can only be reflected by one retroreflector 21 at a time. In some examples, retroreflectors 21 with different orientations can be configured to have a small overlap in receiving angles. This ensures that during the scanning process, the retroreflector 21 to be tracked is selected at the laser tracker 1 or the software control terminal.

[0049] In some examples, a retroreflector can be an optical device such as a cat's eye reflector, a cornerstone prism, or a metal cornerstone reflector that can reflect a beam of light back to the light source along its incident direction.

[0050] In some examples, a photoelectric sensor is positioned behind each retroreflector 21. The retroreflector 21 currently reflecting the positioning laser beam is determined based on the signal from the photoelectric sensor. Specifically, the retroreflector 21 can be a hollow corner cone prism with a through-hole. When the positioning laser beam is reflected by the retroreflector 21, a portion of the positioning laser beam can pass through the through-hole and be emitted to the photoelectric sensor. When the photoelectric sensor receives the positioning laser beam, it can send information. In this case, it is possible to determine whether the current positioning laser beam is aligned with the retroreflector 21 based on the signal from the photoelectric sensor, and to determine which retroreflector 21 reflects the positioning laser beam. Furthermore, it is possible to determine which feature marker structures 22 are used to match the light spot of the monocular attitude camera 12.

[0051] In some examples, by setting a photoelectric sensor behind the retroreflector 21, after determining the retroreflector 21 that is currently reflecting the positioning laser beam, the feature marker structure 22 on the current side can be activated and emit a beam, while the feature marker structures 22 on other sides can be deactivated. This effectively prevents the feature marker structures 22 on other sides from being captured by the monocular attitude camera 12, thus avoiding impact on measurement accuracy.

[0052] In some examples, the feature marker structure 22 can be used to characterize the orientation of the multi-view laser 3D scanner 2. Since the multi-view laser 3D scanner 2 has multiple retroreflectors 21 with multiple orientations, multiple sets of feature marker structures 22 can be provided for each retroreflector 21. Taking four retroreflectors 21 as an example, the upper side, left side, right side and rear side each include at least 6 feature marker structures 22. For example, 6, 7, 8, 9 or 10 feature marker structures 22 can be set. The orientation of the multi-view laser 3D scanner 2 can be uniquely determined by multiple feature marker structures 22.

[0053] In some examples, the layout of the feature marker structure 22 on different sides is different, and the retroreflector 21 of the current reflection positioning laser beam is determined based on the layout of the feature marker structure 22. In this case, the retroreflector 21 of the current reflection positioning laser beam can be determined even if no photoelectric sensor is placed behind the retroreflector 21, which can reduce the size and weight of the multi-view laser 3D scanner 2 and make it easier to carry and scan.

[0054] In some examples, among multiple feature marker structures 22 located on the same side, at least two feature marker structures 22 have lines connecting them that are parallel to the lines connecting the other two feature marker structures 22. In other words, on the same side, there are more than four feature marker structures 22, and two feature marker structures 22 have lines connecting them that are parallel to the lines connecting the other two feature marker structures 22. In this case, in the image captured by the monocular attitude camera 12, the four light spots forming parallel lines can be distinguished from other light spots. This is because the light spots presented by the feature marker structures 22 with parallel relationships remain parallel during the rotation of the multi-view laser 3D scanner 2. Therefore, by setting parallel and non-parallel feature marker structures 22, the light spots in the image captured by the monocular attitude camera 12 can be quickly grouped, making it easier to determine the correspondence between the feature marker structures 22 and the light spots later.

[0055] In some examples, the feature marker structure 22 is an LED or other light source capable of emitting a light beam. In other examples, the feature marker structure 22 may also be a reflective tag or other marker capable of reflecting a light beam. The light beam emitted by the feature marker structure 22 may have a large divergence angle, or the feature marker structure 22 may be a diffuse reflective tag, allowing the illumination light to reflect the beam in multiple directions. Therefore, the monocular attitude camera 12 can simultaneously acquire light beams emitted or reflected by multiple feature marker structures 22.

[0056] In some examples, where the feature marker structure 22 is the light source, the multi-view laser 3D scanner 2 may also include a circuit board for controlling the feature marker structure 22. The circuit board can control the feature marker structure 22 on one side to emit light simultaneously, while the feature marker structures 22 on other sides are simultaneously turned off. In this case, it is possible to prevent the feature marker structures 22 on other sides from affecting the acquisition of pose information by the multi-view laser 3D scanner 2.

[0057] In some examples, the signal for determining which side of the feature marker structure 22 is activated can be provided by the photoelectric sensor located behind the retroreflector 21 as described above.

[0058] In some examples, the signal for determining which side of the feature marker structure 22 is activated can also be given based on the layout of the feature marker structure 22. In some examples, at the start of the measurement, the side facing the positioning laser beam can be determined based on the position of the light spot formed by the feature marker structure 22 acquired by the monocular attitude camera 12. This side, which is also the side where the retroreflector 21 of the current positioning laser beam is located (hereinafter referred to as the alignment surface), can be determined. After determining the alignment surface, the feature marker structures 22 on other sides can be turned off, thereby reducing the influence of the feature marker structures 22 on other sides. If, during the scanning process, the light spot cannot match the feature marker structure 22 of the alignment surface identified at the previous moment, it can be determined that the current alignment surface has changed. At this time, the feature marker structures 22 on each side or adjacent sides of the alignment surface can be activated sequentially until the alignment surface is re-determined based on the position of the light spot. Specifically, the feature marker structures 22 can be controlled in groups and at different times. The feature marker structures 22 set on the same side can be in the same group, and the feature marker structures 22 in the same group can be controlled to be activated or deactivated simultaneously. When the retroreflector 21 of the positioning laser beam is not determined, the feature marker structures 22 on different sides are activated at different times. The feature marker structures 22 activated when a match is successful are recorded, and the retroreflector 21 of the positioning laser beam is determined. Then, the feature marker structures 22 on other sides are deactivated. Since the spot image acquired by the monocular attitude camera 12 can be used in real time for matching the feature marker structure 22 with the spot, by sequentially activating the feature marker structures 22 on different sides, when the feature marker structure 22 on the side facing the laser tracker 1 is activated, a successful match can be achieved. Therefore, based on the feature marker structure 22 activated when a successful match is achieved, the side facing the laser tracker 1 can be determined, and the retroreflector 21 of the laser reflection positioning can be identified. At the same time, after identifying the retroreflector 1 of the laser reflection positioning, the feature marker structures 22 on other sides can be turned off in time, and only the feature marker structure 22 on the alignment surface can be activated to avoid affecting the attitude measurement results.

[0059] In some examples, different groups of feature marker structures 22 can be activated sequentially at a rate of no less than 50 times per second, thereby enabling the laser tracker 1 to determine the alignment surface in real time and ensuring scanning continuity.

[0060] In some examples, at least a portion of the feature marker structure 22 is mounted on the housing via extension posts 25. This extension posts 25 prevent other parts of the feature marker structure 22 from being obscured, while also expanding the layout space of the feature marker structure 22, improving the stability and robustness of the model, and consequently, the accuracy of pose calculation. Furthermore, it reduces the size and weight of the multi-view laser 3D scanner 2.

[0061] In some examples, the feature marker structure 22 is disposed at the end of the extension post 25, and the end has guide holes 251 with different orientations. The feature marker structure 22 is embedded within the end, and it emits or reflects light beams through the guide holes 251 in different directions. Therefore, the direction of the emitted or reflected light beams by the feature marker structure 22 can be constrained by the guide holes 251, preventing the feature marker structures 22 on other sides from being recognized by the attitude camera.

[0062] In some examples, the end of the extension post 25 may also be provided with multiple feature marking structures 22 facing different directions. For example, at the end of the same extension post 25, each guide hole 251 may have an independent feature marking structure 22. In some examples, different feature marking structures 22 can be independently controlled to open or close.

[0063] In some examples, the multimodal laser assembly 24 and multiple scanning imaging cameras 23 are positioned on the front side of the scanner, and the retroreflector 21 is arranged at least on the rear side of the scanner. This enables the front side to be used for laser scanning and the rear side to be used for positioning of the multi-view laser 3D scanner 2.

[0064] In some examples, the imaging laser beam emitted by the multimode laser component 24 is a line laser and includes single-line laser mode, multi-line parallel laser mode and multi-line cross laser mode, thereby meeting different scenarios.

[0065] In some examples, the multi-view laser 3D scanner 2 may include two, three, or more scanning imaging cameras 23, preferably two. Taking two scanning imaging cameras 23 as an example, during the measurement process, the laser points in the imaging laser beams captured by the two scanning imaging cameras 23 are matched based on the epipolar geometry principle. Then, the coordinates of each laser point in the scanning camera coordinate system are measured using the trigonometric similarity principle to form point cloud data. Specifically, the two scanning imaging cameras 23 can capture and capture two imaging laser beam images respectively. Using epipolar constraints and laser plane projection, the matching laser points in the two laser beam images can be uniquely determined. Then, based on the camera intrinsic and extrinsic parameters determined after calibration, and the trigonometric similarity principle, the laser point can be measured to obtain the coordinates of the corresponding position of the laser point in the scanning camera coordinate system. By using multiple scanning imaging cameras, the depth information of the laser point can be calculated from the image positions of the same laser point on different scanning imaging cameras. This provides stronger resistance to ambient light interference and higher reliability. Moreover, based on the measurement principle of multi-view cameras, even if the multimode laser component 24 is replaced, recalibration is not required, making it more convenient to use.

[0066] In some examples, the multi-view laser 3D scanner 2 may include two scanning imaging cameras 23, with a multimodal laser assembly 24 located between the two scanning imaging cameras 23.

[0067] In some examples, the two scanning imaging cameras 23 have overlapping fields of view, and the angle between the optical axes of the two scanning imaging cameras 23 is in the range of 30° to 60°.

[0068] In some examples, multiple light sources can be arranged around the scanning imaging camera 23 on the front side to uniformly illuminate the object under test and eliminate the effects of shadows.

[0069] In some examples, the lower side of the multi-view laser 3D scanner 2 may have a grip and at least one button 26 located on the grip. The button 26 may be used to start the scan or to switch the mode of the imaging laser beam, allowing it to switch freely between single-line laser mode, multi-line parallel laser mode, and multi-line intersecting laser mode.

[0070] This invention also relates to a tracking laser three-dimensional imaging method, which can achieve large-area three-dimensional imaging and achieve high-precision transfer station effect by tracking a multi-view laser three-dimensional scanner 2 with a laser tracker 1, thereby improving measurement accuracy. The tracking laser three-dimensional imaging method can be applied to the tracking laser three-dimensional imaging system described above.

[0071] In some examples, refer to Figure 8 The tracking-type laser 3D imaging method includes: Step S0100: The aiming unit 11 emits a positioning laser beam; Step S0200: The aiming unit 11 acquires the positioning laser beam reflected by the retroreflector 21 and calculates the position information of the multi-view laser 3D scanner 2; Step S0300: The monocular attitude camera 12 captures the beams emitted or reflected by multiple feature marker structures 22 and acquires spot images; Step S0400: The retroreflector 21 that currently reflects the positioning laser beam is determined, and each spot in the spot image is matched with the feature marker structure 22, and the attitude information of the multi-view laser 3D scanner 2 is calculated; Step S0500: Based on the position information and attitude information, the feature point coordinate system and the laser tracker are acquired. The first transformation relationship between coordinate systems; Step S0600: Based on the positional relationship between the feature marker structure 22 and the scanning imaging camera 23, obtain the second transformation relationship between the scanning camera coordinate system and the feature point coordinate system; Step S0700: The multi-mode laser assembly 24 emits an imaging laser beam; Step S0800: Multiple scanning imaging cameras 23 acquire images of the imaging laser beam; Step S0900: Match the imaging laser beams acquired by each scanning imaging camera 23 to calculate the point cloud data of the surface of the object under test in the scanning camera coordinate system; Step S1000: Unify the point cloud data acquired by the multi-view laser 3D scanner 2 at different positions and / or different attitudes to the laser tracker coordinate system.

[0072] After the aiming unit 11 emits the positioning laser beam in step S0100, the aiming unit 11 can be rotated by using the position of the light spot in the position sensor until the positioning laser beam is aligned with the retroreflector 21.

[0073] In step S0200, after the positioning laser beam emitted by the aiming unit 11 is aligned with the retroreflector 21, the spatial coordinates of the vertex of the retroreflector 21 in the laser tracker coordinate system can be obtained according to the absolute ranging principle and / or the interferometric ranging principle, thereby obtaining the position information of the multi-view laser 3D scanner 2. In the laser tracker coordinate system, with the tracker horizontally positioned and the aiming unit 11 reset, the direction of the positioning laser emission is the positive X-axis, and vertically upward is the positive Z-axis. Based on X and Z, the positive Y-axis is defined using the right-hand rule.

[0074] In step S0300, the monocular attitude camera 12 rotates or moves in the same direction and at the same speed as the aiming unit 11, so that it can capture multiple feature marker structures 22 on the multi-eye laser 3D scanner 2 in real time and obtain spot images. Since multiple feature marker structures 22 can emit or reflect light beams, each feature marker structure 22 is presented as a spot in the spot image captured by the monocular attitude camera 12. At this time, the two-dimensional position coordinates of each spot in the image can be obtained.

[0075] In step S0400, the retroreflector 21 of the current reflection positioning laser beam can be determined by the photoelectric sensor set behind the retroreflector 21, or by the feature marking structures 22 arranged on each side, or by the feature marking structures 22 that emit or reflect different colors on each side.

[0076] In some instances, when matching the light spot in the light spot image with the feature marker structure 22 of the alignment surface, since the light spots of the feature marker structures 22 have parallel or equilateral positional relationships, they can also maintain the corresponding positional relationships. Therefore, multiple feature marker structures 22 and light spots can be grouped according to parallelism or similarity, such as feature marker structures A, B, C, D, E, and light spots a, b, c, d, e. Among them, feature marker structures A, B, C, D and light spots a, b, c, d can all form parallel lines. Then it can be determined that light spot e matches feature marker structure E, thereby achieving fast matching.

[0077] In some instances, after matching is completed, the attitude information of the multi-view laser 3D scanner 2 can be calculated based on the position of each light spot in the light spot image and the spatial coordinates of the corresponding feature marker structure 22 in the feature point coordinate system.

[0078] In some instances, the feature point coordinate system can be a coordinate system with the vertex of the retroreflector 21 that is currently reflecting the positioning laser beam as the origin, the incident direction of the positioning laser beam as the positive X-axis, the direction vertically upward facing the retroreflector 21 as the positive Z-axis, and the direction horizontally to the left as the positive Y-axis. In the case of multiple retroreflectors 21 located on four different sides, four independent feature point coordinate systems can be created based on the retroreflectors 21 on each side, and the spatial coordinates of the multiple feature marker structures 22 on different sides in the corresponding feature point coordinate systems can be determined through calibration. The advantage of setting four independent feature point coordinate systems is that the vertices of the four retroreflectors 21 facing different directions may not be located at the same position. The position information calculated by the laser tracker 1 is the spatial coordinate of the vertex of the retroreflector 21 of the current reflection positioning laser beam in the laser tracker coordinate system. Therefore, in order to reduce the computational complexity when calculating the attitude information of the multi-view laser 3D scanner 2, the attitude information of the retroreflector 21 of the current reflection positioning laser beam can be used as the multi-view laser 3D scanner 2. In other words, the multi-view laser 3D scanner 2 can refer to the attitude information of the retroreflector 21 of the current reflection positioning laser beam in the laser tracker coordinate system. The attitude information can be represented by a rotation matrix or Euler angles.

[0079] In step S0500, the first transformation relationship between the feature point coordinate system and the laser tracker coordinate system is obtained based on the position information and attitude information. Therefore, the coordinates located in the feature point coordinate system can be unified to the laser tracker coordinate system through the first transformation relationship.

[0080] In step S0600, the second transformation relationship between the scanning camera coordinate system and the currently used feature point coordinate system can be obtained based on the positional relationship between the feature marker structure 22 and the scanning imaging camera 23. Since the position of the feature marker structure 22 in the multi-view laser 3D scanner 2 is fixed, the second transformation relationship can be obtained through calibration before measurement and called during the scanning process.

[0081] In some examples, since multiple independent feature point coordinate systems are created, the positional relationship between each feature point coordinate system and the scanning camera coordinate system is different. Each independent feature point coordinate system has a corresponding second transformation relationship. Therefore, during the scanning process, the feature point coordinate system currently in use can be determined based on the retroreflector 21 of the currently aligned positioning laser beam, and then the corresponding second transformation relationship can be confirmed and invoked.

[0082] In step S0900, point cloud data of the surface of the object to be measured in the coordinate system of the scanning camera can be obtained. Based on the principle of epipolar geometry, each laser point in the imaging laser beam captured by the two scanning imaging cameras 23 can be matched, and then the coordinates of each laser point in the coordinate system of the scanning camera can be measured using the principle of trigonometric similarity to form point cloud data.

[0083] In some examples, the multi-view laser 3D scanner 2 can send image information to a control terminal (such as a computer with specific software or a dedicated terminal) in real time. The control terminal matches valid image information and calculates point cloud data based on the return of the positioning laser beam, and unifies the valid point cloud data into the laser tracker coordinate system. Since the laser tracker 1 can only be considered to have the positioning laser beam aligned with any retroreflector 21 if it can receive the returned positioning laser beam and the returned positioning laser beam is in a preset position, the image information acquired by the multi-view laser 3D scanner 2 is valid image information. During the scanning process of the multi-view laser 3D scanner 2, there may be situations where there is occlusion or the positioning laser beam is not aligned with the retroreflector 21. In this case, even if the point cloud data is calculated from the image information acquired during the process, it cannot be unified into the laser tracker coordinate system. Therefore, processing only the valid image information can avoid wasting computing power.

[0084] In some examples, during the matching process between the light spot and the feature marker structure 22, the matching accuracy may be low, making it difficult to guarantee the accuracy of the first transformation relationship. In this case, the image information obtained in the process can also be considered invalid image information.

[0085] Step S1000: Unify the point cloud data acquired by the multi-view laser 3D scanner 2 at different positions and / or different attitudes to the laser tracker coordinate system. In this step, the point cloud data acquired by the multi-view laser 3D scanner 2 at different positions and / or different attitudes can be unified to the laser tracker coordinate system based on the first and second transformation relationships. Since the position and / or attitude may change during the scanning process of the multi-view laser 3D scanner 2, it is necessary to unify the point cloud data to the laser tracker coordinate system to achieve the merging of point cloud data in the same coordinate system.

[0086] In some examples, the same location may be scanned multiple times during the scanning process. Therefore, there may be multiple data points for the same measurement location of the object under test. In this case, the final result can be obtained by averaging.

[0087] While the present disclosure has been specifically described above in conjunction with the accompanying drawings and embodiments, it is to be understood that the above description does not limit the present disclosure in any way. Those skilled in the art can make modifications and variations to the present disclosure as needed without departing from its essential spirit and scope, and all such modifications and variations fall within the scope of the present disclosure.

Claims

1. A tracking laser three-dimensional imaging system, comprising a laser tracker and a multi-view laser three-dimensional scanner, The laser tracker includes: The system includes an aiming unit capable of emitting a positioning laser beam, a rotation drive mechanism that drives the aiming unit to rotate in alignment with the multi-eye laser 3D scanner, and a monocular attitude camera linked to the aiming unit. The multi-view laser 3D scanner includes: a housing, multiple retroreflectors disposed in different orientations of the housing, multiple feature marker structures arranged around the housing and capable of emitting or reflecting light beams, a multimode laser assembly for emitting imaging laser beams toward the object under test, and multiple scanning imaging cameras for capturing images of the imaging laser beams on the object under test. During the measurement process, the aiming unit aligns with a retroreflector to obtain the distance between the multi-view laser 3D scanner and the laser tracker, and calculates the position information of the multi-view laser 3D scanner by combining the rotation angle of the aiming unit. Simultaneously, the monocular attitude camera captures images of the multiple feature marker structures to obtain the attitude information of the multi-view laser 3D scanner. Based on the position information and the attitude information, a first transformation relationship is obtained between the coordinate system of the laser tracker and the coordinate system of the feature points on the multi-view laser 3D scanner. Based on the positional relationship between the feature marker structures and the scanning imaging camera, a second transformation relationship is obtained between the coordinate system of the scanning camera and the coordinate system of the feature points. The imaging laser beams captured by each of the scanning imaging cameras are matched to calculate the point cloud data of the surface of the object under test in the scanning camera coordinate system. Based on the first transformation relationship and the second transformation relationship, the point cloud data acquired by the multi-view laser 3D scanner at different positions and / or different postures are unified to the laser tracker coordinate system.

2. The tracking laser three-dimensional imaging system according to claim 1, characterized in that, The multi-view laser 3D scanner includes four retroreflectors, which are respectively disposed on the upper side, left side, right side and rear side of the multi-view laser 3D scanner.

3. The tracking laser three-dimensional imaging system according to claim 2, characterized in that, Each retroreflector is equipped with a photoelectric sensor behind it, and the retroreflector for reflecting and positioning the laser beam is determined based on the signal sent by the photoelectric sensor.

4. The tracking laser three-dimensional imaging system according to claim 3, characterized in that, The feature marker structure serves as the light source, and the retroreflector, based on the reflective positioning laser beam, controls the activation or deactivation of the feature marker structures on each side.

5. The tracking laser three-dimensional imaging system according to claim 2, characterized in that, The upper side, the left side, the right side, and the rear side each include at least six feature marker structures. The layout of the feature marker structures on different sides is different. The retroreflector for the reflective positioning laser beam is determined based on the layout of the feature marker structures.

6. The tracking laser three-dimensional imaging system according to claim 5, characterized in that, When the retroreflector of the laser beam is not determined, the feature marking structures on different sides are activated at different times. The feature marking structures activated when the match is successful are recorded and the retroreflector of the laser beam is determined. Then the feature marking structures on other sides are turned off.

7. The tracking laser three-dimensional imaging system according to claim 4, characterized in that, Four independent feature point coordinate systems are created based on the retroreflectors on different sides. During the measurement process, the corresponding feature point coordinate systems and the second transformation relationship are determined based on the retroreflectors that position the laser beam by reflection.

8. The tracking laser three-dimensional imaging system according to claim 2, characterized in that, Among the plurality of feature marker structures located on the same side, at least two feature marker structures are connected by lines that are parallel to the lines that are connected by other two feature marker structures.

9. The tracking laser three-dimensional imaging system according to claim 1, characterized in that, The multimode laser assembly emits line lasers, including single-line laser mode, multi-line parallel laser mode, and multi-line cross laser mode.

10. The tracking laser three-dimensional imaging system according to claim 7, characterized in that, The multi-view laser 3D scanner includes two scanning imaging cameras. During the measurement process, based on the principle of epipolar geometry, each laser point in the imaging laser beam captured by the two scanning imaging cameras is matched, and then the coordinates of each laser point in the coordinate system of the scanning camera are measured using the principle of trigonometric similarity to form point cloud data.

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