A Method for Measuring the Spatial Pose of a Curved Surface Structure and a Common Point Device for Measurement

Abstract

The present invention discloses a method for measuring the spatial pose of a curved surface structure and a common point device for measurement, belonging to the technical field of industrial measurement. The device is used for coordinate conversion between a total station and photogrammetry. The common point device has a cuboid structure, and an installation structure for connecting with the measured curved surface structure is arranged on its back; a reflector installation position is arranged on the top of the common point device, and the reflectors include a photogrammetry reflector and a total station measurement reflector. The present invention uses the technology of combining a photogrammetry system and a total station, adopts a high-precision common point device as a transition reference, and realizes high-precision and efficient conversion of the photogrammetry coordinate system to the total station coordinate system only through one common point conversion. It solves the problem that it is difficult to associate the external coordinate system after photogrammetry of the curved surface structure.

Description

Technical Field

[0001] The present invention belongs to the field of industrial measurement, and relates to a method for measuring the spatial pose of a curved surface structure and a common point device for measurement. Background Art

[0002] The measurement of the spatial pose of a curved surface structure plays a crucial role in the inspection, calibration, debugging and operation of industrial equipment such as machinery, electronics, and optics. The measurement of the spatial pose of a curved surface structure refers to calibrating the coordinates of many feature points on the surface of the curved surface structure in a specific spatial coordinate system.

[0003] The characteristics of a digital close-range industrial photogrammetry system are as follows:

[0004] 1. It can achieve the rapid measurement and high-precision processing of many feature points on the surface of a curved surface structure;

[0005] 2. The coordinate system of the measurement project is independent and relative;

[0006] 3. Its optical principle limits the distance and angle between the object to be measured and the camera.

[0007] Therefore, a digital close-range industrial photogrammetry system can perform curved surface measurement, but it is difficult to establish a connection with a geodetic coordinate system or a specified spatial coordinate system.

[0008] The characteristics of a total station measurement system are as follows:

[0009] 1. It has the performance of high-precision angle measurement and distance measurement;

[0010] 2. It has the function of establishing a spatial coordinate system;

[0011] 3. It has the performance of long-distance measurement and can achieve the establishment of a high-precision control network;

[0012] 4. It can only observe one point at a time, which limits the measurement efficiency;

[0013] 5. The instrument needs to be erected on a stable foundation.

[0014] Therefore, a total station measurement system can establish a high-precision spatial coordinate system, but it is difficult to collect a large number of measurement marks on the surface of a curved surface point by point and cannot adapt to the measurement of the complex postures of products.

[0015] The essence of the measurement of the spatial pose of a curved surface structure is to realize the conversion of the photogrammetry coordinate system to the total station coordinate system. To address this problem, a reflector target recognizable by a total station can be installed on the camera, and the positional relationship between the reflector target and the photogrammetry camera can be calibrated to input conditions for the conversion of the two coordinate systems.

[0016] The Chinese patent technical solution with the publication number CN104964673A installs positioning devices such as prisms and dials on a photogrammetric camera and calibrates them. During use, the attitude of the camera is determined through the dial, and a total station is used to measure the prism to achieve the positioning of the camera's position. While the camera shoots the object to be measured, the position and attitude of the camera are obtained. The camera uses the method of spatial intersection to shoot the object to be measured, and through calculation, the spatial pose of the object to be measured is obtained.

[0017] This method limits the movement and standing position of the camera, and cannot perform intersection shooting on objects to be measured with complex postures. Moreover, camera positioning and attitude determination are required for each shooting, and a stable camera mounting device is needed, which cannot adapt to the free shooting operation of large curved surface structures.

[0018] With the development of China's science and technology, high-precision curved surface structures play a crucial role in more and more fields. In view of the fact that the existing technology is difficult to meet the requirements, there is an urgent need for a method for measuring the spatial pose of curved surface structures with high efficiency and high precision. Summary of the Invention

[0019] To avoid the deficiencies of the existing technology, the present invention proposes a method for measuring the spatial pose of a curved surface structure based on a total station and photogrammetry. By using a special common point device, a one-time conversion from the photogrammetry coordinate system to the total station coordinate system is realized, and the measurement of the spatial pose of the measured curved surface structure is achieved.

[0020] To achieve the above purpose, the technical solution adopted by the present invention is:

[0021] A common point device for measuring the spatial pose of a curved surface structure, which is used for the coordinate conversion between a total station and photogrammetry. The common point device has a cuboid structure, and an installation structure for connecting with the measured curved surface structure is provided on its back; a reflector installation position is provided on the top of the common point device, and the reflector includes a photogrammetry reflector and a total station measurement reflector.

[0022] Further, the reflector installation positions are all in a grid structure of a Chinese character "tian", and the grid structure of a Chinese character "tian" is engraved on the top of the common point device by means of numerical control mechanical scribing.

[0023] Further, the grid structures of a Chinese character "tian" are all on the same plane of the common point device.

[0024] Further, the side length of the grid structure of a Chinese character "tian" is the same as the side length of the selected photogrammetry reflector, and the intersection point of the cross lines in the grid structure of a Chinese character "tian" coincides with the center of the photogrammetry reflector.

[0025] Further, the number of the grid structures of a Chinese character "tian" is three, and the central positions of the grid structures of a Chinese character "tian" are on a straight line and have equal spacing.

[0026] Further, the tic-tac-toe grid located in the middle position is used to install the reflector for total station measurement, and the tic-tac-toe grid structures on both sides are used to install the reflectors for photogrammetry.

[0027] Further, the installation structure is a process hole or a clamping structure.

[0028] A method for measuring the spatial pose of a curved surface structure based on total station and photogrammetry. During the measurement, a common point device for measuring the spatial pose of the curved surface structure is used, and the specific steps are as follows:

[0029] Step 1: According to the actual site conditions, design the total station station positions, plan the layout of the control network target points, install the common point device, design the measurement plans such as the layout plan of the photogrammetry target points and the movement trajectory of the photogrammetry camera, and set up the total station and prism according to the plan, paste the target points, and arrange the common point device around the measured curved surface structure;

[0030] Step 2: Establish a spatial control network using the total station based on the coordinates of the control points;

[0031] Step 3: Use the total station to measure the coordinates of the reflector for total station measurement on the common point device in the target coordinate system;

[0032] Step 4: Use the photogrammetry camera to take pictures of the curved surface structure and the common point device according to the principle of spatial intersection;

[0033] Step 5: Based on the coordinates of the common points measured by the total station, convert the coordinates of the common points measured by photogrammetry to it, obtain the transformation matrix, and perform coordinate transformation on each point on the surface of the curved surface structure measured by photogrammetry using this transformation matrix to obtain the coordinates of the points on the surface of the curved surface structure in the target coordinate system.

[0034] Further, in Step 1, the total station setup should meet the visibility conditions, that is, the total station can see all the control points and all the common point devices, and the distance should meet the requirements of equipment setup and observation, and the instrument setup should be stable and reliable.

[0035] Further, the layout plan of the photogrammetry target points in Step 1, that is, paste the reflectors suitable for the photogrammetry system on the surface of the curved surface structure, paste the coding marks for photo stitching, arrange a reference scale for point coordinate scale conversion at any position, and paste an orientation target for defining the initial coordinate system of photogrammetry at any position.

[0036] Further, one end of the common point device is a hole, a hoop or a fastener that can be connected to the measured object, and the other end is successively pasted with a photogrammetry reflection mark, a total station reflection mark, and a photogrammetry reflection mark, and the three reflection marks are collinear and equidistant.

[0037] Further, in step 1, at least 4 common point devices shall be deployed, which shall be evenly distributed on the edge of the measured curved surface structure, being stable and reliable, ensuring visibility by the total station, and meeting the attitude requirements for intersection shooting by the photogrammetry camera at the same time.

[0038] Further, in step 2, use the total station to establish a target coordinate system through control points with known coordinates. The number of control points shall be at least 3. Use two of them to establish the coordinate system and the other one for verification. The total station can be set up at one of the control points, and the target coordinate system can be established by using the method of setting up the station with the back sight on another control point, and the third control point is used for verification.

[0039] Further, in step 5, in the photogrammetry system coordinate system, for two measurement points of the same common point device, calculate the midpoint. This midpoint coincides with the measurement point of the total station in space; based on the coordinates of the common point measured by the total station, align the midpoint coordinates measured by photogrammetry with it in space to obtain the transformation matrix, realizing the transformation from the photogrammetry coordinate system to the total station coordinate system, and at the same time, the coordinates of the measurement points on the surface of the curved surface structure in the total station coordinate system can be obtained.

[0040] The present invention mainly has the following advantages:

[0041] 1. The present invention proposes a method for measuring the pose of a curved surface by combining a total station and photogrammetry. This method can realize the transformation from the photogrammetry coordinate system to the total station coordinate system only through one conversion of common points, solves the problem of difficult association between the photogrammetry coordinate system and the external coordinate system, and has high conversion accuracy and operation efficiency;

[0042] 2. The present invention designs a high-precision common point device. After this device is deployed, it can provide a coordinate conversion reference for multiple rounds of photogrammetry and equipment debugging. During the measurement operation, it is no longer necessary for the operator to manually place the target, replace the target, and align it in sequence. The effect of long-term use can be achieved with one deployment, and it has the advantages of low cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is the layout of the example and the site;

[0044] Figure 2 is Figure 1 the enlarged view of part A in

[0045] Figure 3 the front view of the common point device.

[0046] Figure 4 is the side view of the common point device.

[0047] In the figure, 1 - total station, 2 - industrial photogrammetry camera, 3 - measured curved surface structure, 4 - common point device, 5 - circular prism, 6 - measuring pier with known coordinates, 7 - reflector sheet for total station measurement, 8 - reflector sheet for photogrammetry, 9 - coded target for photogrammetry, 10 - reference ruler for photogrammetry, 11 - orientation target for photogrammetry

[0048] Specific implementation cases

[0049] The present invention will be described in detail below with reference to the accompanying drawings through embodiments.

[0050] Embodiment 1:

[0051] A common point device 4 for measuring the spatial pose of a curved surface structure, which is used for coordinate conversion between a total station and photogrammetry. The common point device has a cuboid structure, and an installation structure is provided thereon for connecting with the measured curved surface structure; a reflector sheet installation position is provided on the common point device, and the reflector sheet includes a reflector sheet for photogrammetry and a reflector sheet for total station measurement.

[0052] Further, the installation position is a cross-grid structure, and the cross-grid structure is processed by numerical control mechanical scribing.

[0053] Further, the cross-grid structure is located on the same plane of the common point device.

[0054] Further, the size of the cross-grid structure is preferably 15 mm square, and the crosshair is centered.

[0055] Further, the number of the cross-grid structures is three, the central positions of the cross-grid structures are on a straight line, and the distance between each other is 100 mm.

[0056] Further, the cross-grid in the middle position is used to install the reflector sheet for total station measurement, and the cross-grid structures on both sides are used to install the reflector sheets for photogrammetry. The reflector sheet 7 for total station measurement is characterized by a circular opaque patch with a small hole with a diameter of 1 mm at the center of the circle; the reflector sheet 8 for photogrammetry is characterized by a square opaque patch with a coating covered with circular glass microbeads with a diameter of 12 mm thereon.

[0057] When the cross-grid structure is in use: Align the center circular hole of the reflector sheet for total station measurement with the center of the cross-grid and paste it, and align the outline of the reflector sheet for photogrammetry with the outer outline of the cross-grid and paste it. Each reflector sheet can be conveniently and accurately pasted to ensure that the reflector sheets are equidistant and collinear.

[0058] A method for measuring the spatial pose of a curved surface structure based on a total station and photogrammetry according to the present invention includes the following steps:

[0059] Step 1: Measurement preparation work: For Figure 1For the illustrated example of site conditions, set up total station 1 and two circular prisms 5 for station setting, install eight common point devices 4, paste photogrammetric target points 8 and design the measurement trajectory, specifically including:

[0060] A. Set up the total station on the illustrated survey pier, set up the circular prism on the illustrated survey pier, adjust the circular prism and the sighting board to face the total station directly and be in sight, and the coordinates of the three survey piers in the target coordinate system are all known;

[0061] B. As Figure 1 shown, evenly install 8 common point devices around the object to be measured, adjust the attitude to make the total station visible, and meet the photogrammetry conditions;

[0062] C. Paste reflectors 8 adapted to the photogrammetry system on the surface of the curved surface structure at intervals of 500 mm; paste coding marks 9 for photo stitching at intervals of 2500 mm; arrange a reference scale 10 for point coordinate scale conversion at any position; paste an orientation target 11 for specifying the initial coordinate system of photogrammetry at any position;

[0063] Step 2: Establish the target coordinate system: Set up the total station 1 at the control point to establish a spatial control network, observe a circular prism 5, establish the target coordinate system by the method of backsight station setting, and use another circular prism 5 to check the coordinate accuracy of the coordinate system;

[0064] Step 3: Measure the coordinates of the common points in the target coordinate system: Use the total station to measure the coordinates of the reflector for total station measurement on the common point device in the target coordinate system;

[0065] Step 4: Photogrammetry of the curved surface structure: The operator rides on the articulated boom lift and holds the photogrammetry camera 2, and according to the requirements of space intersection, completes the shooting of the curved surface structure, ensuring that all reflectors 8 on the curved surface structure 3 and the common point device 4 are covered, and the number and quality of the photos meet the requirements of image processing;

[0066] Step 5: Data processing: In the photogrammetry system coordinate system, for the two measurement points of the same common point device, calculate the midpoint, and this midpoint coincides with the total station measurement point in space; based on the coordinates of the common points measured by the total station, align the midpoint coordinates measured by photogrammetry with it in space, obtain the transformation matrix, realize the transformation of the photogrammetry coordinate system to the total station coordinate system, and at the same time, the coordinates of the measurement points on the surface of the curved surface structure in the total station coordinate system can be obtained.

[0067] The above are only the preferred implementation cases of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and true scope of the present invention shall be included within the protection scope of the present invention.

Claims

1. A common point device for measuring the spatial position and orientation of a curved surface structure, characterized in that, this device is used for coordinate transformation between total station and photogrammetry. The common point device has a cuboid structure, and an installation structure for connecting with the measured curved surface structure is provided on its back; a reflector installation position is provided on the top of the common point device, and the reflectors include a photogrammetry reflector and a total station measurement reflector; the reflector installation positions are all in a grid structure in the shape of a Chinese character "tian", and the grid structure in the shape of a Chinese character "tian" is engraved on the top of the common point device by means of numerical control mechanical scribing; the number of the grid structures in the shape of a Chinese character "tian" is three, and the central positions of the grid structures in the shape of a Chinese character "tian" are on a straight line and have equal spacing; the grid structure in the middle position is used to install the reflector for total station measurement, and the grid structures on both sides are used to install the reflectors for photogrammetry.

2. The common point device for measuring the spatial position and orientation of a curved surface structure according to claim 1, characterized in that, the grid structures in the shape of a Chinese character "tian" are all on the same plane of the common point device.

3. The common point device for measuring the spatial position and orientation of a curved surface structure according to claim 1, characterized in that, the side length of the grid structure in the shape of a Chinese character "tian" is the same as the side length of the selected photogrammetry reflector, and the intersection point of the cross lines in the grid structure in the shape of a Chinese character "tian" coincides with the center of the photogrammetry reflector.

4. The common point device for measuring the spatial position and orientation of a curved surface structure according to claim 1, characterized in that, the installation structure is a process hole or a clamping structure.

5. A method for measuring the spatial position and orientation of a curved surface structure based on total station and photogrammetry, characterized in that, during measurement, a common point device for measuring the spatial position and orientation of a curved surface structure according to any one of claims 1 to 4 is used, and it specifically includes the following steps: Step 1: According to the actual site conditions, design the total station station positions, plan the layout of the control network target points, install the common point device, design the measurement schemes such as the layout scheme of the photogrammetry target points and the movement trajectory of the photogrammetry camera, and set up the total station and prism according to the scheme, paste the target points, and arrange the common point device around the measured curved surface structure; Step 2: Establish a spatial control network using the total station according to the control point coordinates; Step 3: Use the total station to measure the coordinates of the reflector for total station measurement on the common point device in the target coordinate system; Step 4: Use the photogrammetry camera to photograph the curved surface structure and the common point device according to the principle of spatial intersection; Step 5: Based on the common point coordinates measured by the total station, convert the common point coordinates measured by photogrammetry to it, obtain the conversion matrix, and perform coordinate transformation on each point on the surface of the curved surface structure measured by photogrammetry using this conversion matrix to obtain the coordinates of each point on the surface of the curved surface structure in the target coordinate system.

6. The method for measuring the spatial position and orientation of a curved surface structure based on total station and photogrammetry according to claim 5, characterized in that, in Step 1, the total station should meet the visibility conditions, that is, the total station can see all control points and all common point devices, and the distance should meet the requirements of equipment station setting and observation, and the instrument should be set up stably and reliably.

7. The method for measuring the spatial position and orientation of a curved surface structure based on total station and photogrammetry according to claim 5, It is characterized in that In step 1, the layout scheme of photogrammetric target points, that is, paste reflectors adapted to the photogrammetric system on the surface of the curved structure, paste coding marks for photo stitching, arrange a reference scale for point coordinate scale conversion at any position, and paste an orientation target for defining the initial coordinate system of photogrammetry at any position.

8. A method for measuring the spatial pose of a curved structure based on a total station and photogrammetry according to claim 5 It is characterized in that One end of the common point device is a hole, a clamp or a fastener that can be connected to the object to be measured. The other end is successively pasted with a photogrammetric reflector, a total station reflector, and a photogrammetric reflector, and the three reflectors are collinear and equidistant.

9. A method for measuring the spatial pose of a curved structure based on a total station and photogrammetry according to claim 5 It is characterized in that In step 1, at least 4 common point devices are deployed, which should be evenly arranged on the edge of the curved structure to be measured, stable and reliable, ensuring that the total station is visible, and at the same time meeting the attitude of the photogrammetric camera for intersection shooting.

10. A method for measuring the spatial pose of a curved structure based on a total station and photogrammetry according to claim 5 It is characterized in that In step 2, use the total station to establish a target coordinate system through control points with known coordinates. The number of control points is at least 3. Use two of them to establish the coordinate system, and use the other one for verification. The total station is set up at one of the control points, and the target coordinate system is established by using the method of setting up the station with the other control point as the backsight, and the third control point is used for verification.

11. A method for measuring the spatial pose of a curved structure based on a total station and photogrammetry according to claim 5 It is characterized in that In step 5, in the coordinate system of the photogrammetric system, for two measurement points of the same common point device, calculate the midpoint. This midpoint coincides with the total station measurement point in space; based on the coordinates of the common point measured by the total station, align the midpoint coordinates measured by photogrammetry with it in space to obtain the transformation matrix, realize the transformation of the photogrammetric coordinate system to the total station coordinate system, and at the same time, the coordinates of the measurement points on the surface of the curved structure in the total station coordinate system can be obtained.

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