Measurement Method and System for Large and Complex Curved Surface Parts Based on Combined Relay Method

Abstract

This invention belongs to the field of measurement technology, specifically relating to a measurement method and system for large, complex curved surface parts based on a combined relay method. This invention combines a laser tracker and a 3D scanner. The 3D scanner performs sectional measurements on the large, complex curved surface part, while the laser tracker is used both for direct measurement and for tracking and positioning the 3D scanner. This invention establishes a coordinate transformation matrix between the 3D scanner and the laser tracker through common point optimization and performs error correction on the data measured by the 3D scanner. The laser tracker is used to accurately locate the 3D scanner during each station transition, thereby unifying the benchmark of the point cloud data obtained from different sectional measurements. Finally, the laser tracker directly measures specific areas within the large, complex curved surface part to complete the entire measurement task. This invention solves the problem of existing technologies' difficulty in achieving accurate and efficient measurement of large, complex curved surface parts.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology, specifically relating to a measurement method for large and complex curved surface parts based on a combined relay method, as well as a data processing module and a measurement system for large and complex curved surface parts that implement the measurement method. Background Technology

[0002] The aviation, aerospace, and communications industries have a wide demand for high-precision large curved surface structural components. For example, the wings, fuselages, and radars of large aircraft have extremely high requirements for the precision of complex curved surfaces. If the product precision cannot meet the requirements, it may directly affect the performance and safety of the aircraft. In order to ensure the precision of large and complex curved surface parts, technicians need to perform multi-point surface measurements on the machined parts.

[0003] There are many methods for measuring the surface accuracy of structural components. Traditional measurement techniques mainly include contact measurement and optical measurement. Contact measurement involves moving a measuring element along the surface of the object being measured, and then measuring the fine contour of the object by combining the movement trajectory. Optical measurement, on the other hand, involves continuously scanning a series of points on the surface of the object being measured, thereby obtaining point cloud data that characterizes the contour of the object. These two traditional measurement techniques are capable of handling the surface measurement tasks of most small curved structural components, but they often face many limitations when dealing with large curved surfaces. For example, contact measurement may not be able to achieve full coverage due to the irregularity of the surface, resulting in incomplete data acquisition; while optical measurement may be affected by the reflective properties of the surface or limitations in measurement distance.

[0004] A 3D scanner is a typical optical measurement instrument used to acquire point cloud data of the appearance of an object. This device can typically only perform rapid measurements on small curved surfaces. If large, complex curved surfaces need to be measured, the 3D scanner needs to be moved between different locations, scanning the large, complex curved surface in sections, and finally integrating the measurement results from different sections. While this measurement strategy can achieve omnidirectional scanning of large curved structural parts to some extent, the frequent station changes during the measurement process not only reduce measurement efficiency but also cause the measurement data generated by the 3D scanner to accumulate a large amount of error, thus significantly reducing the accuracy of the final measurement result.

[0005] With the continuous development of industrial technology, the industry's demand for precise measurement of large curved surfaces is increasing, and the accuracy requirements for large and complex curved surface parts are also constantly improving. Traditional measurement methods are no longer sufficient to meet the demands for high precision and high efficiency. How to develop a solution that can adapt to the characteristics of large and complex curved surface parts and achieve high-precision and high-efficiency measurement of curved surface structures has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the lack of a solution in existing technologies for the accurate and efficient measurement of large and complex curved surface parts, this invention provides a measurement method for large and complex curved surface parts based on a combined relay method, as well as a data processing module and a measurement system for large and complex curved surface parts that implement this measurement method.

[0007] The technical solution provided by this invention is as follows:

[0008] A measurement method for large and complex curved surface parts based on a combined relay method is proposed. This method utilizes a 3D scanner and a laser tracker and employs a combined relay method to collect the overall point cloud data of the complex and large curved surface parts.

[0009] The measurement method includes the following steps:

[0010] S1: Fix the spatial positions of the laser tracker and the large, complex curved surface part to be measured, and install a mobile multi-degree-of-freedom robotic arm between them; then install a 3D scanner at the end of the mobile multi-degree-of-freedom robotic arm, and arrange several spherical mirrors on the base of the 3D scanner. The laser tracker measures the relative position of the 3D scanner by tracking the spherical mirrors on the base of the mobile multi-degree-of-freedom robotic arm.

[0011] S2: Use a laser tracker to measure the spatial position of the spherical mirrors arranged on the 3D scanner, and record it as the initial position of the 3D scanner.

[0012] S3: Multiple spherical mirrors are arranged on the large, complex curved surface part to be tested and used as common reference points; the position information of the common reference points is simultaneously measured using a laser tracker and a 3D scanner. The 3D scanner, mounted on a mobile multi-degree-of-freedom robotic arm, avoids the optical path of the laser tracker detecting the common reference points.

[0013] S4: Using the common point optimization method, calculate the coordinate transformation matrix H between the 3D scanner and the laser tracker based on the position information of the common reference points measured by the laser tracker. The coordinate transformation matrix H is used to calculate the correction value of the 3D scanner's scanning and detection results, using the laser tracker's measurement results as the standard.

[0014] S5: The mobile multi-degree-of-freedom robotic arm moves the 3D scanner to perform partitioned scanning of the large and complex curved surface part to be tested; and the laser tracker measures the new position of the 3D scanner after each movement.

[0015] S6: Record the point cloud data of each partition acquired by the 3D scanner, and based on the initial and new positions of the 3D scanner measured by the laser tracker; combined with the coordinate transformation matrix H, calculate the point cloud data of each partition and the corresponding reference offset ΔL:

[0016]

[0017] Among them, (x ik ,y ik ,z ik (x) represents the coordinates of the common point measured by the 3D scanner before the k-th transfer station; (x) jk ,y jk ,z jk () represents the coordinates of the common point measured by the 3D scanner after the kth transfer station; This represents the reference coordinates of the 3D scanner.

[0018] S7: Combining the coordinate transformation matrix H of the 3D scanner and laser tracker, the point cloud data of each partition, and the corresponding reference offset ΔL, generate the overall point cloud data of the large, complex curved surface part to be measured. The process is as follows:

[0019] S71: Adjust the coordinate values ​​of the point cloud data of each partition in combination with the reference offset ΔL to ensure that the coordinates of all data points are referenced to the same reference.

[0020] S72: Merge the point cloud data in each partition after unifying the baseline into a complete point cloud data, ensuring that the point cloud data in each partition are correctly aligned and avoiding overlap or misalignment.

[0021] S73: Using the coordinate transformation matrix H, the point cloud data merged in the previous step is transformed from the local coordinate system of the 3D scanner to the global coordinate system of the laser tracker to obtain the overall point cloud data.

[0022] S8: Spherical mirrors are placed in special areas of large, complex curved surfaces that cannot be scanned by a 3D scanner. A laser tracker then performs direct measurements, and the results are added to the overall point cloud data. The 3D scanner, mounted on a mobile multi-degree-of-freedom robotic arm, avoids the detection optical path of the laser tracker.

[0023] As a further improvement of the present invention, in step S3, the number of common reference points is not less than 3.

[0024] As a further improvement of the present invention, in step S4, the coordinate transformation matrix H has the following format:

[0025]

[0026] In the above formula, R 3×3 (αβγ) represents the rotation matrix of the coordinate system; α, β, γ are the rotation angles of a point in space along the x, y, and z axes; T 3×1 (T x T y T z) represents the translation vector of each point, Tx, T y T and Tz are the translations of a point in space relative to the origin on the x, y, and z axes, respectively.

[0027] As a further improvement of the present invention, the rotation matrix R 3×3 (αβγ) satisfies the following equation:

[0028]

[0029] As a further improvement of the present invention, the correction value The expression satisfies the following:

[0030]

[0031] In the above formula, Cartesian coordinates representing a common reference point measured by a 3D scanner; A coordinate system representing the transformation between the coordinates of the laser tracker and the Cartesian coordinates measured by the 3D scanner; This indicates the coordinates of a common reference point measured by a 3D scanner within the laser tracker. This represents the offset of the common reference point measured by the 3D scanner relative to the origin of the 3D scanner.

[0032] As a further improvement of the present invention, in step S7, the homogeneous coordinates Q of any observation point acquired by the laser tracker are... gi In the laser tracker measurement coordinate system O G -X G Y G Z G The middle is represented as P gi :

[0033]

[0034] Any observation point Q acquired by the 3D scanner si In the coordinate system O of the 3D scanner S -X S Y S Z S Homogeneous coordinates in P are represented as P si :

[0035]

[0036] The coordinate transformation formulas for the same observation point acquired by the laser tracker and the 3D scanner in different coordinate systems are as follows:

[0037] P gi = G H S P si

[0038] In the above formula, G H S This represents the transformation matrix between the laser tracker and the 3D scanner.

[0039] As a further improvement of the present invention, in step S7, the homogeneous coordinates Q of the spherical mirror are... ci In the coordinate system O of the laser tracker G -X G Y G Z G The middle is represented as P ci :

[0040]

[0041] In the coordinate system O of the laser tracker G -X G Y G Z G In the diagram, the coordinates Q of the spherical mirror are... ci It can be calculated using the following formula:

[0042] P ci = G H I Q ci

[0043] In the above formula, G H I This represents the transformation matrix between measurements taken by the 3D scanner and measurements taken by the laser tracker.

[0044] As a further improvement of the present invention, in step S7, a transformation matrix is ​​used to convert the measurement values ​​of the 3D scanner to the coordinate system of the laser tracker. I H S The expression is as follows:

[0045]

[0046] In the above formula, yes G H I The inverse matrix.

[0047] The present invention also includes a data processing module, which includes a memory, a processor, and a computer program stored in the memory. When the processor executes the computer program, it employs the steps described above in the measurement method for large and complex curved surface parts based on the combined relay method to perform coordinate transformation on the point cloud data measured by the laser tracker and the 3D scanner in their respective coordinate systems.

[0048] The present invention also includes a measurement system for large and complex curved surface parts, comprising: a laser tracker, a mobile multi-degree-of-freedom robotic arm, a 3D scanner, multiple spherical reflectors, and a host computer.

[0049] The laser tracker is mounted on the base. A fixing mechanism is used to secure the large, complex curved surface part to be measured. A mobile multi-degree-of-freedom robotic arm is fixedly mounted between the laser tracker and the fixing mechanism, located closer to the fixing mechanism. A 3D scanner is mounted at the end of the multi-degree-of-freedom robotic arm.

[0050] Some of the spherical mirrors are mounted on the base of the 3D scanner to assist the laser tracker in measuring the relative position of the 3D scanner. Other spherical mirrors are placed on the large, complex curved surface part to be measured, enabling direct measurement of specific areas within that part.

[0051] The host computer is electrically connected to the laser tracker, the mobile multi-degree-of-freedom robotic arm, and the 3D scanner. The host computer controls and records the operating status of the laser tracker, the mobile multi-degree-of-freedom robotic arm, and the 3D scanner, and collects measurement data from the laser tracker and the 3D scanner. This enables the implementation of the steps in the aforementioned measurement method for large, complex curved surface parts based on a combined relay method, obtaining the overall point cloud data of the large, complex curved surface part to be measured.

[0052] The technical solution provided by this invention has the following beneficial effects:

[0053] This invention provides a measurement method and system for large, complex curved surface parts based on a combined relay method. This technical solution combines the advantages of both a laser tracker and a 3D scanner. The laser tracker performs error correction and position tracking on the 3D scanner, and direct measurement is used to supplement the point cloud data of local areas. This overcomes the problems of low efficiency and poor accuracy inherent in traditional methods using 3D scanners for station-to-station measurements.

[0054] This invention integrates multiple measurement technologies, such as laser scanning and structured light scanning, to achieve comprehensive and high-precision measurement of large, complex curved surface parts. The system design takes into account various challenges that may arise during the measurement process, such as ambient light interference, the complexity of curved surface parts, and the instability of measurement equipment. Advanced algorithms and data processing technologies ensure the accuracy and reliability of the measurement results.

[0055] Furthermore, the measurement system for large, complex curved surface parts provided by this invention manages each component through a host computer and automatically performs spatial coordinate transformations from data from different sources. Therefore, it possesses a high degree of automation and intelligence, reducing manual intervention and significantly improving measurement efficiency while lowering operational complexity. Because the system provided by this invention ensures the consistency and accuracy of measurement results, it further reduces measurement errors.

[0056] The measurement method and system for large and complex curved surface parts based on the combined relay method provided by this invention can not only meet the high standard requirements of current industrial fields for the measurement of large and complex curved surface parts, but also provide new possibilities for the future development and application of measurement technology. Attached Figure Description

[0057] Figure 1 This is a spatial layout diagram of the laser tracker and 3D scanner in the measurement method provided in Embodiment 1 of the present invention.

[0058] Figure 2 This is a flowchart of the measurement method for large and complex curved surface parts based on the combined relay method provided in Embodiment 1 of the present invention.

[0059] Figure 3 This is a system schematic diagram of the measurement system for large, complex curved surface parts provided in Embodiment 3 of the present invention.

[0060] The diagram is marked as follows:

[0061] 1. Laser tracker; 2. Fixing mechanism; 3. Mobile multi-degree-of-freedom robotic arm; 4. 3D scanner; 5. Spherical reflector; 6. Host computer. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0063] Example 1

[0064] After analysis, the technical personnel of this embodiment believe that the main reasons for the large errors in the point cloud data of large curved surfaces acquired by existing solutions using 3D scanners are as follows: First, the accuracy of the data acquired by the 3D scanner itself is relatively low. Second, the single scanning range of the 3D scanner is limited, and the spatial position of the 3D scanner is difficult to accurately locate during frequent station changes, resulting in a large accumulation of errors in the point cloud data of different areas due to changes in the reference. Third, the 3D scanner is poor at measuring the concave or irregular structures of some special parts. Therefore, in order to overcome the above-mentioned defects of 3D scanners in the measurement of large and complex curved surface parts, this embodiment provides a measurement method for large and complex curved surface parts based on a combined relay method, which is used to combine a 3D scanner and a laser tracker to acquire the overall point cloud data of large and complex curved surface parts.

[0065] Specifically, the overall approach of the solution provided in this embodiment is to combine a laser tracker and a 3D scanner. The laser tracker is used both for direct measurement of certain areas of the surface structure under test and for tracking and locating the 3D scanner. In this new measurement system, the laser tracker plays three roles: first, it establishes a coordinate transformation matrix between the 3D scanner and the laser tracker through common point optimization, and corrects errors in the 3D scanner's detection data; second, it accurately locates the 3D scanner during each station transfer, thereby unifying the benchmark of point cloud data obtained from measurements in different zones; and third, it directly measures local areas of the surface under test that are unsuitable for 3D scanning, obtaining more accurate point cloud data.

[0066] In detail, such as Figure 1 As shown, the measurement method for large and complex curved surface parts based on the combined relay method provided in this embodiment includes the following steps:

[0067] S1: This embodiment first requires constructing a measurement system for a large, complex curved surface part, including a laser tracker and a 3D scanner, and then installing the large, complex curved surface part to be measured. For example... Figure 2 As shown, in this embodiment, the laser tracker and the large, complex curved surface part to be measured need to be fixedly installed to maintain their positions in space. This embodiment also installs a mobile multi-degree-of-freedom robotic arm between the laser tracker and the large, complex curved surface part; and mounts a 3D scanner at the end of the mobile multi-degree-of-freedom robotic arm. In this embodiment, considering that the mobile multi-degree-of-freedom robotic arm needs to move the 3D scanner relative to the laser tracker to achieve sectional measurement of the large, complex curved surface part, the mobile multi-degree-of-freedom robotic arm should be located close to the large, complex curved surface part. Finally, several spherical reflectors are arranged on the base of the 3D scanner. Figure 2In the measurement system, the laser tracker measures the spatial position of the 3D scanner relative to itself by tracking the spherical mirror on the base.

[0068] S2: Use the laser tracker to measure the spatial position of the spherical mirror arranged on the 3D scanner and record it as the initial position of the 3D scanner.

[0069] In this embodiment, some spherical mirrors supporting the laser tracker are fixedly installed on the base of the 3D scanner, and the laser tracker realizes position tracking of the 3D scanner through the spherical mirror on the base. Additionally, if direct measurement of the surface to be measured is required, the spherical mirror can be directly placed on the surface of the large and complex surface part to be measured.

[0070] Since it is necessary to use the laser tracker to track the position change of the 3D scanner during the measurement process, the laser tracker needs to measure and record the position of the 3D scanner before and after each station transfer of the 3D scanner.

[0071] S3: Arrange multiple spherical mirrors on the large and complex surface part to be measured and use them as common reference points, and use the laser tracker and the 3D scanner to measure the position information of the common reference points simultaneously.

[0072] Among them, the 3D scanner installed on the mobile multi-degree-of-freedom robotic arm avoids the optical path of the laser tracker for detecting the common reference points.

[0073] In the measurement system constructed in this embodiment, the scanning area of the 3D scanner is limited and the measurement accuracy is relatively low, but it can achieve multi-point scanning on the surface. Although the laser tracker has very high measurement accuracy, it can only measure the spatial positions of a small number of points in the large and complex surface part by tracking the spherical mirror, and it is not suitable for morphological scanning of large and complex surface parts and is difficult to obtain a large amount of point cloud data.

[0074] On this basis, the solution of this embodiment uses the 3D scanner and the laser tracker to measure a set of common reference points, and then establishes the coordinate transformation relationship between the 3D scanner and the laser tracker according to the measurement results of the two, and corrects the measurement results of the 3D scanner through the corresponding coordinate transformation matrix.

[0075] In practical applications, this embodiment arranges no fewer than three spherical mirrors on the large, complex curved surface part to be tested, using the position of each spherical mirror as a common reference point. In this embodiment, the three spherical mirrors should be placed at intervals on the surface of the large, complex curved surface part to be tested, thus forming a plane. Next, this embodiment uses a laser tracker and a 3D scanner to simultaneously measure the position information of the common reference point; and obtains the spatial coordinates of each common reference point in the respective measurement coordinate systems of the laser tracker and the 3D scanner.

[0076] S4: Using the common point optimization method, calculate the coordinate transformation matrix H between the 3D scanner and the laser tracker based on the position information of the common reference points measured by the laser tracker. The coordinate transformation matrix H includes correction values ​​for the 3D scanner's scanning results calculated using the laser tracker's measurement results as the standard.

[0077] In this embodiment, the process of determining the coordinate transformation matrix H between the 3D scanner and the laser tracker based on the common point optimization method is as follows:

[0078] Assume there are n selected common reference points, denoted as D. i For i = 1…n, the homogeneous coordinates P of each common reference point under the 3D scanning instrument can be obtained through the measurement in step S3. i1 :

[0079] P i1 =(x pi1 ,y pi1 ,z pi1 ,1)

[0080] And the homogeneous coordinates P of each common reference point under the laser tracker i2 :

[0081] P i2 =(x pi2 ,y pi2 ,z pi2 ,1)

[0082] Since the locations measured by both instruments are public points, the two homogeneous coordinates can be converted to each other using the following coordinate transformation matrix H:

[0083] P i1 =HP i2 i = 1, 2, ..., n

[0084] Wherein, the coordinate transformation matrix H is a homogeneous transformation matrix, and the format of the matrix is:

[0085]

[0086] In the above formula, R 3×3 (αβγ) represents the rotation matrix of the coordinate system; α, β, γ are the rotation angles of a point in space along the x, y, and z axes; T 3×1 (T x T y T z ) represents the translation vector of each point, Tx, T y Let T and Tz be the translations of a point in space relative to the origin along the x, y, and z axes, respectively. The rotation matrix R is... 3×3 (αβγ) satisfies the following equation:

[0087]

[0088] Based on the coordinate transformation matrix H, this embodiment can transform the point cloud data measured by the 3D scanner to the coordinate system corresponding to the laser tracker. The coordinate transformation matrix H is an intermediate coordinate system. Based on this, the error correction strategy implemented in this embodiment is as follows:

[0089] This embodiment optimizes the rotation matrix and translation vector in the coordinate transformation matrix using a common point optimization method to minimize error. Specifically, multiple common reference points are measured at M locations. If the coordinate system of the first location is taken as the reference coordinate system, the Cartesian coordinates of the common point obtained by the laser tracker and the 3D scanner at the first location can be expressed as: and

[0090]

[0091] For ease of distinction, the superscript G0 in the coordinates of each point represents the first position (position 0) of the laser tracker coordinate system (G), and the subscript gi represents the i-th point in the laser tracker coordinate system (g). Both G and g are labels for the laser tracker coordinate system. Similarly, the superscript S0 represents the first position (position 0) of the 3D scanner coordinate system (S), and the subscript si represents the i-th point in the 3D scanner coordinate system (s). Both S and s are labels for the 3D scanner coordinate system.

[0092] Based on this, common points measured at other locations and The Cartesian coordinates can be represented as:

[0093]

[0094] Where m represents the sequence number of each common point.

[0095] After introducing measurement errors into both coordinate systems, the transformation method of the coordinate transformation matrix can be rewritten as follows:

[0096]

[0097] In the above formula, This indicates that the common reference point measured by the laser tracker is in Cartesian coordinates; The coordinate system representing the transformation between the laser tracker coordinates and the standard coordinates of the external environment; The Cartesian coordinates of the common reference point measured by the laser tracker; This indicates the offset between the common reference point measured by the laser tracker and the origin of the laser tracker; Cartesian coordinates representing a common reference point measured by a 3D scanner; Cartesian coordinates representing a common reference point measured by a 3D scanner; The coordinate system representing the transformation between the coordinates of the laser tracker and the Cartesian coordinates measured by the 3D scanner; This indicates the coordinates of a common reference point measured by a 3D scanner within the laser tracker. This represents the offset of the common reference point measured by the 3D scanner relative to the origin of the 3D scanner.

[0098] in, and These are the correction values ​​for the spatial coordinates of a common reference point measured in the laser tracker and the 3D scanner, respectively:

[0099]

[0100] Considering that this embodiment primarily uses the measurement results of the laser tracker as the standard to calibrate the measurement results of the 3D scanner, the correction value of the laser tracker's measurement results is set to 0 in this embodiment, i.e. The calibration value of the 3D scanner The expression satisfies the following:

[0101]

[0102] S5: The 3D scanner is moved by a multi-degree-of-freedom robotic arm to perform partitioned scanning of large and complex curved surface parts to be tested; and the new position of the 3D scanner after each movement is measured by a laser tracker.

[0103] In this embodiment, when measuring large, complex curved surface parts with different structures and sizes, technicians should develop a measurement plan beforehand. In this plan, the technician divides the entire surface of the large curved surface part to be measured into multiple zones according to the maximum scanning range of the 3D scanner. Then, the technician determines the device pose of the 3D scanner when scanning each zone and issues spatial movement commands to the mobile multi-degree-of-freedom robotic arm. The point cloud data obtained after scanning different zones by the 3D scanner should completely cover the surface of the entire large, complex curved surface part.

[0104] During each sectional scanning process of the mobile multi-degree-of-freedom robotic arm moving the 3D scanner, the laser tracker in this embodiment can dynamically track the 3D scanner using a spherical reflector mounted on the base, and then record the spatial position of the 3D scanner after each station move.

[0105] S6: Record the point cloud data of each partition acquired by the 3D scanner, and based on the initial and new positions of the 3D scanner measured by the laser tracker; combined with the coordinate transformation matrix H, calculate the point cloud data of each partition and the corresponding reference offset ΔL:

[0106]

[0107] Among them, (x ik ,y ik ,z ik (x) represents the coordinates of the common point measured by the 3D scanner before the k-th transfer station; (x) jk ,y jk ,z jk () represents the coordinates of the common point measured by the 3D scanner after the kth transfer station; This represents the reference coordinates of the 3D scanner.

[0108] In this embodiment, the point cloud data of different partitions obtained by the 3D scanner are measured after the station is moved. Therefore, the reference of the point cloud data of each partition is not consistent. The reference offset ΔL corresponding to the point cloud data of each partition reflects the difference of each coordinate value in the point cloud data relative to the common reference.

[0109] S7: Combine the coordinate transformation matrix H of the 3D scanner and laser tracker, the point cloud data of each partition, and the corresponding reference offset ΔL to generate the overall point cloud data of the large and complex curved surface part to be tested.

[0110] In this embodiment, the laser tracker is fixed relative to the base, while the 3D scanner is constantly moving. Therefore, this embodiment uses the measurement coordinate system of the laser tracker as the world coordinate system. Then, the point cloud data measured by the 3D scanner are converted to the measurement coordinate system of the laser tracker after being unified by a common reference, and integrated into complete point cloud data, eliminating duplicate point clouds.

[0111] Specifically, the process of generating the overall point cloud data of a large, complex curved surface part in this embodiment is as follows:

[0112] S71: Adjust the coordinate values ​​of the point cloud data of each partition in combination with the reference offset ΔL to ensure that the coordinates of all data points are referenced to the same reference.

[0113] S72: Merge the point cloud data in each partition after unifying the baseline into a complete point cloud data, ensuring that the point cloud data in each partition are correctly aligned and avoiding overlap or misalignment.

[0114] S73: Using the coordinate transformation matrix H, the point cloud data merged in the previous step is transformed from the local coordinate system of the 3D scanner to the global coordinate system of the laser tracker to obtain the overall point cloud data.

[0115] The process of generating overall point cloud data for large and complex curved surface parts is essentially a coordinate transformation process for point cloud data from different sources. The corresponding data processing can be summarized as follows:

[0116] (1) Homogeneous coordinates Q of any observation point obtained by the laser tracker gi In the laser tracker measurement coordinate system O G -X G Y G Z G It can be represented as P gi :

[0117]

[0118] Any observation point Q acquired by the 3D scanner si In the coordinate system O of the 3D scanner S -X S Y S Z S The homogeneous coordinates in P can be represented as P si :

[0119]

[0120] The coordinate transformation formulas for the same observation point acquired by the laser tracker and the 3D scanner in different coordinate systems are as follows:

[0121] P gi = G H S P si

[0122] In the above formula, G H S This represents the transformation matrix between the laser tracker and the 3D scanner.

[0123] (2) The positional changes of the 3D scanner during partitioned scanning can be confirmed by the movement of the spherical mirror mounted on its base. Specifically, the homogeneous coordinates Q of the spherical mirror... ci In the coordinate system O of the laser tracker G -X G Y G Z GThe middle can be represented as P ci :

[0124]

[0125] In the coordinate system O of the laser tracker G -X G Y G Z G In the diagram, the coordinates Q of the spherical mirror are... ci It can be calculated using the following formula:

[0126] P ci = G H I Q ci

[0127] In the above formula, G H I This represents the transformation matrix between measurements taken by the 3D scanner and measurements taken by the laser tracker.

[0128] Based on the above two points, the transformation matrix used to convert the measurements from the 3D scanner to the coordinate system of the laser tracker can be determined. I H S The expression is as follows:

[0129]

[0130] In the above formula, yes G H I The inverse matrix.

[0131] Based on the determined transformation matrix IH S This embodiment can sequentially transform point cloud data from different zones measured by a 3D scanner to the world coordinate system and delete duplicate point clouds. It is particularly important to emphasize that the coordinate transformation process in this embodiment simultaneously achieves reference offset and error correction, thus resulting in higher accuracy of the final point cloud data.

[0132] S8: Place spherical mirrors in special areas of the large, complex curved surface part that cannot be scanned by a 3D scanner. A laser tracker will then perform direct measurements, and the results will be added to the overall point cloud data from the previous step. The 3D scanner mounted on a mobile multi-degree-of-freedom robotic arm avoids the detection optical path of the laser tracker.

[0133] As discussed above, while laser trackers are not suitable for large-scale surface scanning, they are highly accurate in measuring the spatial position of individual target points. Therefore, this embodiment utilizes this characteristic, employing a laser tracker instead of a 3D scanner to directly measure specific areas of large, complex curved surface parts. This overcomes the limitation of 3D scanners in measuring certain depressions or special structures on the surface of large, complex curved parts, and allows for local supplementation of the incomplete point cloud data acquired by the 3D scanner.

[0134] Example 2

[0135] Based on the scheme of Embodiment 1, this embodiment provides a data processing module, which includes a memory, a processor, and a computer program stored in the memory. When the processor executes the computer program, it adopts the steps in the measurement method for large and complex curved surface parts based on the combined relay method in Embodiment 1 to realize coordinate transformation of the point cloud data measured by the laser tracker and the 3D scanner in their respective coordinate systems.

[0136] The data processing module provided in this embodiment is essentially a computer device, which can take many forms; it can be an embedded chip or module, or a general-purpose data processing device. Examples include smart terminals capable of executing programs, tablet computers, laptops, desktop computers, rack servers, blade servers, tower servers, or cabinet servers (including standalone servers or server clusters composed of multiple servers), etc.

[0137] The computer device of this embodiment includes, but is not limited to, a memory and a processor that can be interconnected via a system bus. The memory (i.e., the readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory may be an internal storage unit of the computer device, such as the hard disk or RAM of the computer device.

[0138] In other embodiments, the memory can also be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Of course, the memory can also include both internal storage units and external storage devices of the computer device. In this embodiment, the memory is typically used to store the operating system and various application software installed on the computer device. Furthermore, the memory can also be used to temporarily store various types of data that have been output or will be output.

[0139] In some embodiments, a processor may be a central processing unit (CPU), a graphics processing unit (GPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor is typically used to control the overall operation of a computer device. In this embodiment, the processor is used to run program code stored in memory or process data.

[0140] Example 3

[0141] Based on Examples 1 and 2, this embodiment further provides a measurement system for large, complex curved surface parts, such as... Figure 3 As shown, the measurement system includes: a laser tracker 1, a mobile multi-degree-of-freedom robotic arm 3, a 3D scanner 4, multiple spherical reflectors 5, and a host computer 6.

[0142] In the measurement system for large, complex curved surface parts provided in this embodiment, a laser tracker 1 is mounted on a base. A fixing mechanism 2 is used to fix the large, complex curved surface part to be measured. A mobile multi-degree-of-freedom robotic arm 3 is fixedly mounted between the laser tracker 1 and the fixing mechanism 2, and is located on the side closer to the fixing mechanism 2. A 3D scanner 4 is mounted on the end of the multi-degree-of-freedom robotic arm.

[0143] Some spherical mirrors 5 are mounted on the base of the 3D scanner 4. Other spherical mirrors 5 are placed on the large, complex curved surface part to be measured, enabling direct measurement of specific areas within that part. In this embodiment, the laser tracker 1 works in conjunction with the spherical mirrors 5 to track the position of the 3D scanner 4 mounted at the end of the mobile multi-degree-of-freedom robotic arm 3, accurately measuring the spatial coordinates of the 3D scanner 4.

[0144] The 3D scanner 4 can perform non-contact scanning of targets, measuring and analyzing their shape, geometric structure, and appearance data. The collected data is stored in the form of point cloud data, which can be used for 3D reconstruction calculations or to create digital models of real objects in the virtual world. In this embodiment, after the 3D scanner 4 is installed at the end of the mobile multi-degree-of-freedom robotic arm 3, the mobile multi-degree-of-freedom robotic arm can move the spatial position of the 3D scanner 4 according to instructions, thereby realizing the partitioned scanning of large and complex curved surface parts.

[0145] In the measurement system for large and complex curved surface parts provided in this embodiment, the host computer 6 is electrically connected to the laser tracker 1, the mobile multi-degree-of-freedom robotic arm 3, and the 3D scanner 4. The host computer 6 includes two main parts: a control unit and a data processing unit. The control unit is used to control the operating status of the laser tracker 1, the mobile multi-degree-of-freedom robotic arm 3, and the 3D scanner 4. The data processing unit is used to acquire the measurement data from the laser tracker 1 and the 3D scanner 4, and to process the obtained data using the steps in the measurement method for large and complex curved surface parts based on the combined relay method in Embodiment 1, thereby obtaining the overall point cloud data of the large and complex curved surface part to be measured.

[0146] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A measurement method for large complex curved surface parts based on combined relay method, characterized in that, It utilizes a three-dimensional scanner and a laser tracker and adopts a combined relay method to realize the collection of overall point cloud data of a complex large curved surface part; the measurement method comprises the following steps: S1: fixing the spatial positions of the laser tracker and the large complex curved surface part to be measured, and installing a mobile multi-degree-of-freedom mechanical arm between the two; then installing a three-dimensional scanner at the end of the mobile multi-degree-of-freedom mechanical arm, and arranging a plurality of spherical mirrors on the base of the three-dimensional scanner; wherein the laser tracker measures the relative position of the three-dimensional scanner through the spherical mirror on the base; S2: measuring the spatial position of the spherical mirror arranged on the three-dimensional scanner by the laser tracker, and recording it as the initial position of the three-dimensional scanner; S3: arranging a plurality of spherical mirrors on the large complex curved surface part to be measured as common reference points, and simultaneously measuring the position information of the common reference points by the laser tracker and the three-dimensional scanner; wherein the three-dimensional scanner installed on the mobile multi-degree-of-freedom mechanical arm avoids the light path of the laser tracker detecting the common reference points; S4: calculating the coordinate conversion matrix H between the three-dimensional scanner and the laser tracker according to the position information of the common reference points measured by the three-dimensional scanner and the laser tracker by using the common point optimization method; The coordinate conversion matrix H is used to calculate a correction value of a scanning detection result of the three-dimensional scanner based on a measurement result of the laser tracker ; S5: moving the three-dimensional scanner by the mobile multi-degree-of-freedom mechanical arm to scan the large complex curved surface part to be measured in sections; and measuring the new position of the three-dimensional scanner after each movement by the laser tracker; S6: record the point cloud data of each subzone collected by the three-dimensional scanner, and according to the initial position and the new position of the three-dimensional scanner measured by the laser tracker, combine the coordinate conversion matrix H to calculate the point cloud data of each subzone and the corresponding reference offset : wherein, represents the coordinates of a common point measured by the three-dimensional scanner before the k first rotation; represents the coordinates of a common point measured by the three-dimensional scanner after the k second rotation; represents the reference coordinates of the three-dimensional scanner; S7: Coordinate conversion matrix H combined with the three-dimensional scanner and the laser tracker, point cloud data of each subzone, and the corresponding reference offset The overall point cloud data of the large complex curved surface part to be measured is generated, and the process is as follows: S71: combine reference offset adjusting coordinate values of the point cloud data of each partition to ensure that the coordinates of all data points refer to the same reference; S72: merging the point cloud data in each section after unifying the reference into a complete point cloud data, ensuring that the point cloud data in each section is correctly aligned, and avoiding overlapping or misplacement; S73: using the coordinate conversion matrix H to convert the point cloud data merged in the last step from the local coordinate system of the three-dimensional scanner to the global coordinate system of the laser tracker to obtain the overall point cloud data; S8: placing a spherical mirror in a special area in the large complex curved surface part which cannot be scanned by the three-dimensional scanner, directly measuring by the laser tracker, and supplementing the measurement results to the overall point cloud data; wherein the three-dimensional scanner installed on the mobile multi-degree-of-freedom mechanical arm avoids the detection light path of the laser tracker.

2. The method for measuring large complex curved surface parts based on combined relay method according to claim 1, characterized in that: In step S3, the number of common reference points is not less than 3.

3. The method for measuring large complex curved surface parts based on combined relay method according to claim 2, characterized in that: In step S4, the coordinate conversion matrix H has the following format: In the above formula, The rotation matrix representing the coordinate system; For a point in space x , y , z Rotation angle on the axis; This represents the translation vector for each point. , and These are points in space relative to the origin. x , y , z Translation on the axis.

4. The method for measuring large complex curved surface parts based on combined relay method according to claim 3, characterized in that: The rotation matrix satisfies the following equation: 。 5. The method for measuring large complex curved surface parts based on combined relay method according to claim 4, characterized in that: correction value satisfies the following expression: In the above formula, represents the Cartesian coordinates of the common reference point measured by the 3D scanner; represents the conversion coordinate system between the laser tracker coordinate and the Cartesian coordinates measured by the 3D scanner; represents the coordinates of the common reference point measured by the 3D scanner in the laser tracker; represents the offset of the common reference point measured by the 3D scanner relative to the origin of the 3D scanner.

6. The method for measuring large complex curved surface parts based on combined relay method according to claim 1, wherein: In step S7, the laser tracker obtains the homogeneous coordinates of any one observation point In the laser tracker measurement coordinate system are expressed as : Any one observation point acquired by the three-dimensional scanner In the homogeneous coordinates in the three-dimensional scanner coordinate system is expressed as : Then the coordinate conversion formula of the same observation point in different coordinate systems obtained by the laser tracker and the three-dimensional scanner is as follows: In the above formula, represents the transformation matrix of the laser tracker and the three-dimensional scanner.

7. The method for measuring large complex curved surface parts based on combined relay method according to claim 6, characterized in that: In step S7, the homogeneous coordinates of the spherical mirror are represented in the coordinate system of the laser tracker as : Then in the coordinate system of the laser tracker the coordinates of the spherical mirror are calculated by the formula: ， In the above formula, represents the transformation matrix between the measurements of the three-dimensional scanner and the measurements of the laser tracker.

8. The method for measuring large complex curved surface parts based on combined relay method according to claim 7, characterized in that: In step S7, a conversion matrix for converting the measurement values of the three-dimensional scanner into the coordinate system of the laser tracker is expressed as follows: In the above formula, is the inverse matrix of 9. A data processing module comprising a memory, a processor and a computer program stored on the memory, characterized in that: When the processor executes the computer program, the steps in the measurement method of the large complex curved surface part based on the combined relay method in any one of claims 1-8 are adopted to realize the coordinate conversion of the point cloud data measured by the laser tracker and the three-dimensional scanner in their respective coordinate systems.

10. A measurement system of a large complex curved surface part, comprising: a laser tracker installed on a base; a fixing mechanism for fixing a large complex curved surface part to be measured; a mobile multi-degree-of-freedom mechanical arm fixedly installed between the laser tracker and the fixing mechanism and located on the side close to the fixing mechanism; a three-dimensional scanner installed at the end of the multi-degree-of-freedom mechanical arm; A plurality of spherical mirrors, wherein part of the spherical mirrors are installed on the base of the three-dimensional scanner for assisting the laser tracker to measure the relative position of the three-dimensional scanner; and another part of the spherical mirrors are placed on the large complex curved surface part to be measured to realize direct measurement on part of the area in the large complex curved surface part to be measured. A host computer electrically connected with the laser tracker, the mobile multi-degree-of-freedom mechanical arm and the three-dimensional scanner; the host computer is used for controlling and recording the running state of the laser tracker, the mobile multi-degree-of-freedom mechanical arm and the three-dimensional scanner, and collecting the measurement data of the laser tracker and the three-dimensional scanner; and then realizing the steps in the measurement method of the large complex curved surface part based on the combined relay method according to any one of claims 1-8, and obtaining the overall point cloud data of the large complex curved surface part to be measured.

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