Terrestrial scanner and laser tracker reference alignment target and method of use

Abstract

This invention relates to a target for aligning a geodetic scanner and a laser tracker, and its method of use. The target includes a disc, a conical cover, and a reflective sphere. Two intersecting first dividing lines passing through the center of the disc separate black and white blocks. A conical notch is formed at the center of the disc, and the conical cover is detachably fitted into the notch, with its end face forming a complete disc surface. The reflective sphere is detachably engaged within the notch, and the reflective sphere and the conical cover are used in a staggered manner. When the reflective sphere is engaged within the notch, its center coincides with the center of the disc surface. The target center point can be obtained simply by removing the conical cover and measuring the center point of the reflective sphere, which is convenient and quick. The measurement repeatability is high, and the center error is better than 0.08 mm compared to the tracker's measurement error.

Description

Technical Field

[0001] This invention relates to a target for aligning a geodetic scanner and a laser tracker, and a method for using the target, belonging to the field of engineering measurement technology. Background Technology

[0002] In recent years, Building Information Modeling (BIM) technology has been increasingly widely used in engineering surveying. Thanks to technological advancements, large-size spatial laser point cloud scanners can now perform high-efficiency, high-precision measurements. Among the more mature geodetic scanners in the industry are Leica's ScanStation P40 and Faroo's Focus Premium. This scanner allows for free spatial station placement, using a black-and-white alternating circular target as a reference for station transfer and adjustment. The scanner scans the black-and-white target to calculate the coordinates of its center point. The measurement method is non-contact, with a measurement accuracy of ±2 mm within 50 meters.

[0003] Laser trackers are currently the most accurate large-scale engineering surveying equipment. Leica's AT960 / 930 series trackers can achieve an accuracy of 1.5 micrometers + 6 micrometers per meter, which is two orders of magnitude higher than that of geodetic scanners. The laser tracker's relocation reference is a conical target holder that can accommodate a 1.5-inch SMR reflecting prism sphere, manufactured using precision machining. Therefore, the tracker's target measurement accuracy can be guaranteed to be within 0.08 millimeters at 10 meters. If the common point reference coordinates measured by the tracker are provided to the geodetic scanner for site transfer and adjustment calculations, the measurement accuracy will be greatly improved. Therefore, designing a common relocation reference that can be recognized by both devices simultaneously can solve this problem. Summary of the Invention

[0004] To address the aforementioned problems, one objective of this invention is to provide a target that is aligned with the reference of a geodetic scanner and a laser tracker. Another objective is to provide a reverse measurement method. The target that is aligned with the reference of the geodetic scanner and the laser tracker can be transformed into a black and white target and a conical target of the tracker's reflective sphere, while ensuring that the centers of the two types of targets are consistent and the overlap error is less than 0.05 mm.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] On one hand, the technical solution of the present invention provides a target target with a reference aligned between a geodetic scanner and a laser tracker, characterized in that it includes:

[0007] A disc, on which two intersecting first dividing lines pass through the center, the two first dividing lines separate the black and white blocks on the disc, and a cone-shaped notch is formed in the center of the disc;

[0008] A conical cover is detachably fitted into the notch. Two second dividing lines passing through the center of the circle are formed on the conical cover. The two second dividing lines separate the black and white blocks on the conical cover. When the conical cover is fitted into the notch, the second dividing lines and the first dividing lines coincide. The end face of the conical cover and the end face of the disk form a complete disk surface.

[0009] The reflector ball is detachably mounted in the notch. The reflector ball and the conical cover are used separately. When the reflector ball is mounted in the notch, the center of the reflector ball coincides with the center of the disc surface.

[0010] Furthermore, the target aligned with the reference of the geodetic scanner and the laser tracker also includes a magnet. The disk has a mounting groove, and the magnet is fixed in the mounting groove. The magnet is used to fix and attract the reflective ball into the notch.

[0011] Furthermore, the target aligned with the reference of the geodetic scanner and the laser tracker also includes a retaining ring, which is fixedly installed in the mounting groove. The retaining ring is located on one side of the magnet and fixes the magnet in the mounting groove.

[0012] Furthermore, a mounting hole is provided on the rear side of the disk, through which the magnet passes, and a screw is inserted into the mounting hole. The screw passes through the mounting hole, the magnet, and the retaining ring in sequence and is fixedly connected to the conical cover.

[0013] Furthermore, it also includes a support device, which comprises a column and a base, with the bottom of the column fixed to the base and the top fixedly connected to the disc.

[0014] Furthermore, the base is provided with several countersunk holes, and bolts are inserted into the countersunk holes, and the base is fixed by the bolts.

[0015] Furthermore, a locking block is provided on one side or on both sides symmetrically opposite to each other on the conical cover, and a locking groove is provided on the disc to match the shape of the locking block. When the conical cover is embedded in the notch, the locking block is inserted into the locking groove.

[0016] On the other hand, the present invention also provides a method for using the aforementioned geodetic scanner and laser tracker reference aligned target, comprising the following steps:

[0017] S1. In the engineering scenario requiring scanning and measurement, a laser tracker and the target target are set up, and the target target encloses the engineering project entity being measured;

[0018] S2. Open the cone-shaped cover of the target, embed the reflective sphere into the notch, measure the center of the reflective sphere using the laser tracker, and calculate the coordinate values ​​of the center of all targets in the design reference coordinate system.

[0019] S3. Take out the reflective ball, cover the conical surface of all the target targets, set up the geodetic scanner in the engineering scene, scan all the target targets, automatically identify the target targets with black and white interval image signals as the reference station, and scan the entity of the engineering project being tested.

[0020] S4. Repeat steps S2 to S3 above to measure data at multiple stations, measuring the same target point at each station.

[0021] S5. Import the measurement data coordinates of the laser tracker and the geodetic scanner into the data processor of the geodetic scanner, set the coordinate point of the center of the sphere as the reference control point of the geodetic scanner, and stitch the scanner data with the coordinates of the reference control point measured by the laser tracker to obtain the engineering scene survey map.

[0022] Furthermore, in step S1, the target spacing is set such that the spacing distance is no greater than 10 meters, and there is a height difference between the target targets.

[0023] Furthermore, the design reference coordinate system is the design reference coordinate system of the accelerator. The method for restoring the design reference coordinate system is to measure the accelerator control network points through the reflector sphere of the control network, and then calculate the position and orientation of the accelerator design reference coordinate system through the point group best fitting function.

[0024] The present invention has the following advantages due to the adoption of the above technical solutions:

[0025] 1. Currently, scanners primarily use high-precision scanning spheres or monochrome targets as reference points. While the center of a scanning sphere can be determined by laser trackers and other equipment, this increases measurement time, requires sampling numerous points on the sphere's surface, and results in significant uncertainty in fitting the sphere's center. This design, however, uses a target that only requires removing the conical cover and measuring a single center point through a reflective sphere to obtain the target's center point. This method is convenient, fast, and offers high repeatability, with the sphere's center error being better than 0.08 mm compared to the tracker's measurement error. Traditional monochrome targets can only be recognized by scanners; trackers cannot obtain their center through contact measurement methods.

[0026] 2. Some engineering projects, such as accelerator projects, are usually designed with a reference control network that determines the global coordinate system through a target datum. This target can be easily used with a laser tracker to introduce the coordinate system of the control network in the accelerator project into the measurement data of the scanner. After the tracker measures the control network to obtain the design reference coordinate system of the project, it measures the target to obtain the coordinates of the target in the design reference coordinate system. The scanner can accurately integrate the point cloud data into the design reference coordinate system through the position data of the target, which is beneficial for digital model comparison and reverse engineering. This is a function that cannot be achieved by using a geodetic scanner alone. Attached Figure Description

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0028] In the attached diagram:

[0029] Figure 1 An exploded view of an embodiment of the target whose reference is aligned between the geodetic scanner and the laser tracker provided by the present invention:

[0030] Figure 2 Schematic diagram of the conical cover adapted for this target:

[0031] Figure 3 yes Figure 2 A cross-sectional view;

[0032] Figure 4 Schematic diagram of SMR reflector sphere adapted for this target:

[0033] Figure 5 for Figure 4 Cross-sectional view:

[0034] The markings in the attached diagram are as follows:

[0035] 1-Disc, 2-Conical cover, 3-Reflective ball, 4-Magnet, 5-Retaining ring, 6-Notch, 7-Screw, 8-Base, 9-Post, 10-Counterhead hole, 11-Slot, 12-Card block. Detailed Implementation

[0036] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0037] This invention provides a target for aligning a geodetic scanner and a laser tracker, and a method for using the target. The target includes a disc, a conical cover, and a reflective sphere. Two intersecting first dividing lines passing through the center of the disc separate black and white blocks. A conical notch is formed at the center of the disc, and the conical cover is detachably fitted into the notch, with its end face forming a complete disc surface. The reflective sphere is detachably engaged within the notch, and the reflective sphere and the conical cover are used in a staggered manner. When the reflective sphere is engaged within the notch, its center coincides with the center of the disc surface. The target center point can be obtained simply by removing the conical cover and measuring the center point of the reflective sphere, which is convenient and quick. The measurement repeatability is high, and the center error is better than 0.08 mm compared to the tracker's measurement error.

[0038] Example 1

[0039] like Figures 1 to 5 As shown, Embodiment 1 of the present invention provides a target for alignment between a geodetic scanner and a laser tracker reference. The target for alignment includes a disk 1, a conical cover 2, and a reflective sphere 3. Two intersecting first dividing lines are formed on the disk 1, separating the black and white blocks on the disk 1. A conical notch 6 is formed at the center of the disk 1. The conical cover 2 is detachably fitted into the notch 6. Two second dividing lines are formed on the conical cover 2, separating the black and white blocks on the conical cover 2. When the conical cover 2 is fitted into the notch 6, the second dividing lines coincide with the first dividing lines, and the end face of the conical cover 2 and the end face of the disk 1 form a complete disk surface. The reflective sphere 3 is detachably engaged within the notch 6. The reflective sphere 3 and the conical cover 2 are used in a staggered manner. When the reflective sphere 3 is engaged within the notch 6, the center of the reflective sphere 3 coincides with the center of the disk surface.

[0040] The target for aligning the geodetic scanner and the laser tracker also includes a magnet 4. The disk 1 has a mounting groove, and the magnet 4 is fixed in the mounting groove. The magnet 4 is used to fix and attract the reflective ball 3 into the notch 6.

[0041] The target for aligning the geodetic scanner and the laser tracker also includes a retaining ring 5, which is fixedly installed in the mounting groove. The retaining ring 5 is located on one side of the magnet 4 and fixes the magnet 4 in the mounting groove.

[0042] The disk 1 has a mounting hole on its rear side, through which the magnet 4 passes. A screw 7 is inserted into the mounting hole, and the screw 7 passes through the mounting hole, the magnet 4, the retaining ring 5, and the reflective ball 3 in sequence to be fixedly connected to the conical cover 2.

[0043] To facilitate installation and fixation, the target aligned with the reference of the geodetic scanner and the laser tracker also includes a support device. The support device includes a column 9 and a base 8. The bottom of the column 9 is fixed to the base 8, and the top is fixedly connected to the disc 1. The base 8 is provided with several countersunk holes 10, and bolts are inserted into the countersunk holes 10. The base 8 is fixed by the bolts.

[0044] To facilitate the removal of the conical cover 2, a locking block 12 is provided on one side or on both sides symmetrically opposite to each other. The disc 1 is provided with a slot 11 that matches the shape of the locking block 12. When the conical cover 2 is embedded in the notch 6, the locking block 12 is inserted into the slot 11.

[0045] The reflective sphere is preferably an SMR (Spherically mounted reflector) spherically mounted reflector.

[0046] The method of using the target includes the following steps:

[0047] S1. In the engineering scenario requiring scanning and measurement, a laser tracker and the target target are set up, and the target target encloses the engineering project entity being measured;

[0048] S2. Open the cone-shaped cover 2 of the target, and insert the reflective ball 3 into the notch 6. Measure the center of the reflective ball 3 of the target using the laser tracker to obtain the precise coordinates of all the target centers.

[0049] S3. Set up a geodetic scanner in the engineering scene, take out the reflective ball 3 and close the cone cover 2 of all the target targets, scan all the target targets, automatically identify the black and white interval image signal as the reference station, and scan the entity of the engineering project being measured.

[0050] S4. Using the fixed target as a reference point for the transfer station, repeat steps S2 to S3 to measure data at multiple stations, with the same target point measured at each station.

[0051] S5. Import the measurement data coordinates from the tracker and the geodetic scanner into the geodetic scanner, and stitch and adjust the data from multiple stations to obtain the engineering scene survey map.

[0052] Currently, scanners primarily use high-precision scanning spheres or monochrome targets as reference points. While the center of a scanning sphere can be determined by laser trackers and other equipment, this increases measurement time, requires sampling numerous points on the sphere's surface, and results in significant uncertainty in fitting the sphere's center. This invention addresses this by providing a target target where the center point can be obtained simply by removing the conical cover 2 and measuring a single point using a reflective sphere. This method is convenient, fast, and offers high repeatability, with the sphere center error being better than 0.08 mm compared to the tracker's measurement error. Traditional monochrome targets can only be recognized by scanners; trackers cannot obtain their center through contact measurement methods.

[0053] Example 2

[0054] Embodiment 2 of the present invention provides a method for using the target aligned with the reference of the geodetic scanner and the laser tracker described in Embodiment 1. Specifically, it is illustrated using a mapping accelerator as an example, and includes the following steps:

[0055] Step 1: Arrange the target positions at the engineering site where the measurement is required. The interval between adjacent target positions should be greater than 5 meters and less than 10 meters. The target positions should be evenly distributed around the accelerator device to enclose the accelerator device. There should be more than 4 target positions, which can be 5 or 6, and there should be a height difference of more than 1 meter. The target positions can be fixed in the designated positions through the countersunk holes on the base 5 to keep the position stable.

[0056] Step 2: Restore the accelerator design reference coordinate system and determine the coordinate values ​​of the center of the target in the reference coordinate system;

[0057] The first station is set up using a laser tracker, which is located in the middle of the visible target in the first section of the accelerator, at a distance that is roughly equal to that of all the target targets.

[0058] Open the conical covers of all targets, embed the SMR reflector 3 into the notch 6, measure the center of the SMR reflector 3 using the laser tracker, calculate the coordinates of the centers of all targets in the accelerator design reference coordinate system, and export the data in text format.

[0059] The recovery accelerator design benchmark includes the following steps:

[0060] The design reference coordinate system of the accelerator is restored by using the existing reference control network of the accelerator project. The reference control network is a set of well-designed target mounts that can accommodate 1.5-inch SMR reflector spheres. The method for restoring the design reference coordinate system of the accelerator is to measure the accelerator control network points through the SMR reflector spheres of the control network, and then calculate the position and orientation of the accelerator design reference coordinate system by using the best fitting function of the point group.

[0061] Step 3: Set up the first station using a geodetic scanner, in the same position as the laser tracker. Scan and measure all visible targets. Remove the reflector sphere 3, close all the open cone covers 2, and fix them with the screws 6 on the back of the disc 1. The target will then be restored to a complete black and white pattern. The target to be measured is the same target measured by the first station of the laser tracker. Set the scanning area and angle range of the geodetic scanner, scan and measure the accelerator engineering scene to be measured, and save the data.

[0062] Step 4: Due to the large scale of the accelerator mapping project, it is generally impossible to complete all data collection at a single station. Therefore, multiple stations need to be set up for measurement. The second station should be about 5 to 10 meters away from the first station. It is best to set up the station to measure as many targets as possible within the accelerator facility and its area. The measurement method for the remaining stations is similar to that of the first station. First, the center coordinates of the target data are obtained using a laser tracker. Then, the measurement software is used to best fit the coordinates of the target center obtained by the laser tracker at the current station location with the center of the same target point from the previous station's data. The data from the two stations are then integrated into the accelerator engineering coordinate system. Finally, a geodetic scanner is used to scan the engineering data and the target points at the transfer stations. The software automatically stitches the data using the transfer station's reference control points.

[0063] Step 5: Finally, process the point cloud measurement data of the geodetic scanner. Import the target data point coordinates measured by the laser tracker into the geodetic scanner's data processor. Set the coordinate point of the sphere's center as the geodetic scanner's relocation reference control point with the highest weight. Stitch the scanner data together using the control point coordinates measured by the laser tracker. The measurement error of these points is less than 0.10 mm, which is far better than the geodetic scanner's 2 mm measurement error. Therefore, after error adjustment of all stitched point clouds, the error will be reduced to less than 1 mm. The data is automatically integrated into the overall coordinate system of the accelerator design layout. This also facilitates the import of the accelerator design model for numerical model comparison or reverse engineering modeling.

[0064] The method described above allows for the convenient use of a laser tracker to incorporate the control network coordinate system of an accelerator project into the measurement data of a scanner. After the tracker measures the control network to obtain the design center coordinate system of the project, it then measures the target to obtain the coordinates of the target under the engineering design reference. The scanner can accurately integrate the point cloud data into the engineering design coordinate system using the target's position data, which is beneficial for digital model comparison and reverse engineering. This is a function that cannot be achieved by using a geodetic scanner alone.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for using a target aligned with a geodetic scanner and a laser tracker reference, characterized in that, The target, aligned with the reference of the geodetic scanner and the laser tracker, includes a disk, a conical cover, a reflective sphere, a magnet, a retaining ring, and a support device. Two intersecting first dividing lines are formed on the disk and pass through the center of the disk. The two first dividing lines separate the black and white blocks on the disk. A cone-shaped notch is formed in the center of the disk. The conical cover is detachably embedded in the notch. Two second dividing lines passing through the center of the circle are formed on the conical cover. The two second dividing lines separate the black and white blocks on the conical cover. When the conical cover is embedded in the notch, the second dividing line and the first dividing line coincide. The end face of the conical cover and the end face of the disk form a complete disk surface. The reflective ball is detachably mounted in the notch. The reflective ball and the conical cover are used separately. When the reflective ball is mounted in the notch, the center of the reflective ball coincides with the center of the disc surface. The disk has a mounting groove, the magnet is fixed in the mounting groove, and the magnet is used to fix and attract the reflective ball into the notch; The retaining ring is fixedly installed in the mounting groove, the retaining ring is located on one side of the magnet, and the retaining ring fixes the magnet in the mounting groove; The disk has a mounting hole on its rear side, through which the magnet passes. A screw is inserted into the mounting hole, and the screw passes through the mounting hole, the magnet, and the retaining ring in sequence to be fixedly connected to the conical cover. The support device includes a column and a base, with the bottom of the column fixed to the base and the top fixedly connected to the disc; The base is provided with several countersunk holes, and bolts are inserted into the countersunk holes. The base is fixed by the bolts. The conical cover has a locking block on one side or on both sides symmetrically opposite to each other, and the disc has a locking groove that matches the shape of the locking block. When the conical cover is inserted into the notch, the locking block is inserted into the locking groove. The method for using the target aligned with the reference of the geodetic scanner and the laser tracker includes the following steps: S1. In the engineering scenario requiring scanning and measurement, a laser tracker and the target target are set up, and the target target encloses the engineering project entity being measured; S2. Open the cone-shaped cover of the target, embed the reflective sphere into the notch, measure the center of the reflective sphere using the laser tracker, and calculate the coordinate values ​​of the center of all targets in the design reference coordinate system. S3. Take out the reflective ball, cover the conical surface of all the target targets, set up the geodetic scanner in the engineering scene, scan all the target targets, automatically identify the target targets with black and white interval image signals as the reference station, and scan the entity of the engineering project being tested. S4. Repeat steps S2 to S3 above to measure data at multiple stations, measuring the same target point at each station. S5. Import the measurement data coordinates of the laser tracker and the geodetic scanner into the data processor of the geodetic scanner, set the coordinate point of the center of the sphere as the reference control point of the geodetic scanner, and stitch the scanner data with the coordinates of the reference control point measured by the laser tracker to obtain the engineering scene survey map.

2. The method of use according to claim 1, characterized in that, In step S1, the target spacing is set such that the spacing distance is no more than 10 meters, and there is a height difference between the targets.

3. The method of use according to claim 1, characterized in that, The design reference coordinate system is the design reference coordinate system of the accelerator. The method for restoring the design reference coordinate system is to measure the accelerator control network points through the reflector sphere of the existing control network of the accelerator, and then calculate the position and orientation of the accelerator design reference coordinate system through the point group best fitting function.

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