A method and apparatus for acquiring three-dimensional deformation field information of a component

Abstract

The application discloses a kind of component three-dimensional deformation field information acquisition method and device, belong to material manufacturing test technical field, the component three-dimensional deformation field information acquisition method includes: from different visual angle obtains the deformation process data of the component to be measured carrying speckle pattern, to extract each visual angle corresponding local deformation data, and it is spliced to obtain initial splicing result;Judgment whether there is overlapping part in the initial splicing result;If there is overlapping part then the initial splicing result is iteratively optimized, until the optimal rigid transformation matrix between each local deformation data is found, and the current optimized splicing result is used as fine splicing result;The continuity check is carried out to the fine splicing result;The fine splicing result that passes check is homogenized, to obtain the three-dimensional deformation field information of the component to be measured;The application can greatly improve the precision of three-dimensional deformation field information acquisition, reduce error.

Description

Technical Field

[0001] This invention belongs to the field of materials manufacturing and testing technology, and more specifically, relates to a method and apparatus for acquiring three-dimensional deformation field information of components. Background Technology

[0002] Digital Image Correlation (DIC), proposed in the 1980s, has been continuously developed and improved, and is now widely used in industrial measurement, materials testing, aerospace, biology, and other fields. Two-dimensional DIC can only measure in-plane displacement and strain; even slight out-of-plane motion can introduce significant errors, severely affecting measurement accuracy. To overcome these limitations, three-dimensional DIC has gained widespread application due to its simple testing equipment, low environmental sensitivity, ease of operation, and high accuracy. However, three-dimensional DIC also has certain limitations, such as situations where the size of the object exceeds the camera's field of view, or where mutual occlusion of objects or complex curvature prevents the camera from covering the surface of the component.

[0003] In recent years, some scholars have used multiple deformation measurement systems to measure components from all angles. Each vision system independently measures a limited area of ​​the object under test, and then the coordinates are transformed to the same coordinate system to obtain the overall deformation data of the component. However, relying solely on coordinate transformation to stitch together local data results in overall deformation data, especially in overlapping areas, with significant errors that fail to reflect the true deformation situation.

[0004] Therefore, there is an urgent need for a method to stitch together and fuse local three-dimensional deformation information to obtain complete three-dimensional deformation data of the surface of the test part, reveal the overall deformation law of the component, and provide key data support for the mechanical performance evaluation and structural optimization of materials and components. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method and apparatus for acquiring three-dimensional deformation field information of a component. The purpose is to iteratively optimize the overlapping portions of the initial splicing result until the optimal rigid body transformation matrix between each local deformation data is found, thereby obtaining a finely matched splicing result. This result is then post-processed to obtain the three-dimensional deformation field information of the component under test. This solves the technical problem of large errors in the acquired deformation information caused by overlapping areas in the overall deformation data in existing measurement methods.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for obtaining three-dimensional deformation field information of a component is provided, comprising:

[0007] S1: Obtain deformation process data of the test component with speckle pattern from different perspectives, extract the local deformation data corresponding to each perspective, and stitch them together to obtain the initial stitching result;

[0008] S2: Determine whether there are overlapping parts in the initial splicing result;

[0009] S3: If there is an overlapping part, the initial splicing result is iteratively optimized until the optimal rigid body transformation matrix between each of the local deformation data is found, and the current optimized splicing result is used as the fine-fit splicing result;

[0010] S4: Perform continuity verification on the fine-fit splicing results;

[0011] S5: The qualified splicing results are homogenized to obtain the three-dimensional deformation field information of the component under test.

[0012] In one embodiment, S5 includes: smoothing and downsampling the qualified precision splicing result to obtain the three-dimensional deformation field information of the component under test.

[0013] In one embodiment, downsampling in S5 includes:

[0014] S5.1: Calculate the bounding box of the overlapping part in the fine splicing result after the inspection is qualified and smoothed, and discretize the bounding box into several squares;

[0015] S5.2: Assign weights to each point within a square based on the distribution of the point set falling within each square, and select the point with the highest weight as the representative point.

[0016] S5.3: The bounding box is characterized by representative points of all squares to obtain the three-dimensional deformation field information of the component under test.

[0017] In one embodiment, S5.2 includes: assigning weights to each point based on the correlation coefficient calculated during deformation of each point within the grid and its distance from the center of gravity within the grid, and selecting the point with the largest weight as the representative point.

[0018] In one embodiment, S5.2 includes: using a formula Assign weights to each point within the grid, and select the point with the highest weight as the representative point; where W(a) represents the weight of that point, C represents the cross-correlation coefficient for deformation correlation calculation, and D... a This indicates the relative distance of the point from the center of gravity.

[0019] In one embodiment, S1 includes: using calibrated different measurement subsystems to acquire deformation process data of the component under test carrying speckle patterns from different perspectives, so as to extract local deformation data corresponding to each perspective; and converting the local deformation data to the same coordinate system as the initial stitching result.

[0020] In one embodiment, after step S2, the method further includes: if there is no overlapping portion, performing a continuity check on the initial splicing result; and smoothing the initial splicing result that passes the check to obtain the three-dimensional deformation field information of the component under test.

[0021] According to another aspect of the present invention, a device for acquiring three-dimensional deformation field information of a component is provided, comprising:

[0022] The splicing module is used to acquire deformation process data of the test component with speckle pattern from different perspectives, extract the local deformation data corresponding to each perspective, and splice them to obtain the initial splicing result.

[0023] The judgment module is used to determine whether there are overlapping parts in the initial splicing result;

[0024] An optimization module is used to iteratively optimize the initial stitching result if there are overlapping parts, until the optimal rigid body transformation matrix between each of the local deformation data is found, and the current optimized stitching result is used as the fine-fit stitching result.

[0025] The verification module is used to verify the continuity of the fine-fit splicing results;

[0026] The post-processing module is used to homogenize the qualified precision splicing results to obtain the three-dimensional deformation field information of the component under test.

[0027] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0028] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0029] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0030] (1) The method for obtaining three-dimensional deformation field information of components provided by the present invention iteratively optimizes the overlapping part in the initial splicing result until the optimal rigid body transformation matrix between each local deformation data is found, thereby obtaining the fine splicing result, and performing continuous verification and other processing to obtain the three-dimensional deformation field information of the component to be tested; it can greatly improve the accuracy of obtaining three-dimensional deformation field information and reduce errors.

[0031] (2) This solution takes into account the unevenness of the fine splicing results, and performs smoothing and downsampling to improve the accuracy of the obtained three-dimensional deformation field information.

[0032] (3) This scheme calculates the bounding box of the overlapping part in the fine-fit splicing result after the inspection is qualified and smoothed, and selects a representative point to represent the bounding box. The representative point can be the center, centroid or any point. This can reduce the computational complexity of the fine-fit splicing result while removing redundancy and filtering, so that the final obtained three-dimensional deformation field information is more reasonable and reliable.

[0033] (4) This scheme assigns weights to each point within the grid based on its correlation coefficient during deformation calculation and its distance from the grid's centroid. For example, points with high correlation and located near the centroid, points with the highest correlation coefficient, points closest to the centroid, or a certain proportion of both can be selected, with the highest-scoring point receiving the maximum weight. The point with the maximum weight is then selected as the representative point. This method considers both the correlation coefficient and its distance from the grid's centroid, ensuring that the selected representative point best represents the true three-dimensional deformation, thus improving the reliability and accuracy of the three-dimensional deformation field information acquisition.

[0034] (5) This scheme provides an optimal weight allocation method, using the formula By assigning weights to each point within the grid, and taking into account factors such as correlation and spatial distance, a more accurate weight allocation method is provided for three-dimensional deformation calculation, thereby more effectively reflecting the true deformation of the component.

[0035] (6) This scheme utilizes calibrated different measurement subsystems to acquire deformation process data of the component under test carrying speckle patterns from different perspectives, so as to extract the local deformation data corresponding to each perspective; the local deformation data is then transformed into the same coordinate system as the initial splicing result. Through calibration and coordinate transformation, the internal and external parameters of each subsystem and the overall external parameter transformation relationship can be determined, thereby reducing the error of the splicing result caused by environmental factors such as coordinates and measurement system parameters.

[0036] (7) This scheme considers a special scenario where the initial splicing result has no overlapping parts. In this case, continuity verification and smoothing are performed, and the result is regarded as the three-dimensional deformation field information of the component under test. The scenario provided by this scheme makes the method of obtaining the three-dimensional deformation field information of the component more complete. Attached Figure Description

[0037] Figure 1 This is a flowchart of a method for obtaining three-dimensional deformation field information of a component according to Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram illustrating the principle of another method for obtaining three-dimensional deformation field information of a component provided in Embodiment 1 of the present invention;

[0039] Figure 3 This is a schematic diagram of the binocular measurement system provided in Embodiment 1 of the present invention. Detailed Implementation

[0040] 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. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Example 1

[0042] like Figure 1 and Figure 2 As shown, this embodiment provides a method for obtaining three-dimensional deformation field information of a component, including: S1: performing speckle processing on the surface of the component to be tested to obtain speckle samples, acquiring deformation process data of the component to be tested carrying speckle patterns from different perspectives, which are continuous multi-frame image data, extracting local deformation data corresponding to each perspective, and stitching them together to obtain an initial stitching result; S2: determining whether there are overlapping parts in the initial stitching result; S3: if there are overlapping parts, iteratively optimizing the initial stitching result until the optimal rigid body transformation matrix between each local deformation data is found, and using the currently optimized stitching result as the fine-fit stitching result; S4: performing continuity verification on the fine-fit stitching result; S5: homogenizing the verified fine-fit stitching result to obtain the three-dimensional deformation field information of the component to be tested.

[0043] Preferably, S1 includes: using calibrated different measurement subsystems to acquire deformation process data of the component under test carrying speckle patterns from different perspectives, so as to extract local deformation data corresponding to each perspective; and converting the local deformation data to the same coordinate system as the initial splicing result.

[0044] In S1, different methods are used to apply speckle patterns to the surface of the component under test, such as spray paint, markers, screen printing, stamps, rollers, and stickers, depending on the experimental requirements and conditions, to obtain speckle samples. For situations where the size of the object exceeds the field of view of a single system, or where the camera cannot cover the component surface due to mutual occlusion or complex curvature, measurement subsystems located at different orientations are used to simultaneously measure the deformation field of the component under test, obtaining three-dimensional deformation data from different parts of the component surface. The measurement processes of each subsystem are relatively independent and do not affect each other. Then, based on the overall system extrinsic parameters, the local deformation data are transformed to the same coordinate system as the initial stitching result of the field cloud. For example, the measurement subsystem used can be a binocular measurement system, such as... Figure 3 As shown, each monocular measurement system may include a CCD camera 1, an industrial lens 2, a filter 3, a light source 4, and a synchronization control device, etc. It measures the deformation field based on the digital image correlation method. By matching the four speckle patterns of the same sample surface before and after deformation from the left and right cameras, it obtains the local three-dimensional deformation field information of the surface at different times during the thermal deformation of the component.

[0045] S2, because each system selects equally spaced points within the region of interest as the points to be calculated when initially calculating the local deformation field, the field cloud data of the measurement results is uniformly distributed. Since no fractures or other abnormalities occur during normal thermal deformation of the component, the measurement results of the deformation field should be smooth and continuous, without sudden strain changes. Therefore, the deformation data can be used to judge overlapping areas in the results and to verify the reliability of subsequent splicing. After the initial splicing, the field cloud density of the initial splicing results is used to determine whether there are overlapping parts. If overlapping parts exist, subsequent fine splicing steps are continued. Preferably, after S2, the following steps are also included: if no overlapping parts exist, the continuity of the initial splicing results is checked; the initial splicing results that pass the check are smoothed to obtain the three-dimensional deformation field information of the component under test.

[0046] S3. For the initial stitching result, the nearest point iteration method or feature matching algorithm (based on SIFT features, based on SURF features, etc.) is used to continuously iterate and optimize the field cloud data in the overlapping area, find the coordinate transformation matrix with the minimum Euclidean distance between corresponding points in the data, so as to maximize the overlap between each field cloud and achieve the optimal registration between each set of data.

[0047] S4. For the precision splicing results, a continuity check is performed based on the three-dimensional deformation information of the component surface to determine the validity and reliability of the data registration, and simultaneously to check the accuracy of the deformation calculations of each local system. The three-dimensional deformation information consists of three-dimensional deformation field data calculated by each subsystem, which has high accuracy and uniform distribution. Furthermore, this data has been smoothed and verified for continuity, thus it can be used to judge the validity of the overall splicing results. In addition, the deformation information can also be used to judge the accuracy of the deformation analysis of the same location on the component by different subsystems. If the splicing results of overlapping parts differ significantly, it indicates that different systems have different measurement results, resulting in measurement errors, and the incorrect output locations are manually judged.

[0048] S5. The overall registration results still have problems such as dense field cloud data in overlapping areas and data redundancy. Therefore, it is downsampled and processed to ensure that the field cloud data is evenly distributed throughout the entire area while maintaining the characteristics of the original field cloud data, so as to obtain uniform and complete three-dimensional deformation field information of the component surface.

[0049] Preferably, S5 includes: smoothing and downsampling the inspected and qualified precision splicing results to obtain the three-dimensional deformation field information of the component under test. Further, the downsampling in S5 includes: S5.1: calculating the bounding box of the overlapping portion in the inspected and smoothed precision splicing results, and discretizing the bounding box into several squares; S5.2: assigning weights to each point within each square according to the distribution of the point set falling within each square, and selecting the point with the highest weight as the representative point; S5.3: using the representative points of all squares to characterize the bounding box, thereby obtaining the three-dimensional deformation field information of the component under test.

[0050] Preferably, S5.2 includes: assigning weights to each point within the grid based on its correlation coefficient during deformation calculation and its distance from the grid's centroid, and selecting the point with the highest weight as the representative point. Further, S5.2 includes: using the formula... Assign weights to each point within the grid, and select the point with the highest weight as the representative point; where W(a) represents the weight of that point, C represents the cross-correlation coefficient for deformation correlation calculation, and D... a This indicates the relative distance of the point from the center of gravity.

[0051] Example 2

[0052] According to another aspect of the present invention, a device for acquiring three-dimensional deformation field information of a component is provided, comprising: a splicing module, a judgment module, an optimization module, a verification module, and a post-processing module. The splicing module is used to acquire deformation process data of the component under test carrying a speckle pattern from different perspectives, to extract local deformation data corresponding to each perspective, and to splice them to obtain an initial splicing result; the judgment module is used to determine whether there are overlapping parts in the initial splicing result; the optimization module is used to iteratively optimize the initial splicing result if overlapping parts exist, until the optimal rigid body transformation matrix between each local deformation data is found, and the currently optimized splicing result is used as the fine-fit splicing result; the verification module is used to perform continuity verification on the fine-fit splicing result; and the post-processing module is used to homogenize the verified fine-fit splicing result to obtain the three-dimensional deformation field information of the component under test.

[0053] Before initial assembly, the measurement system needs to be calibrated for its intrinsic and extrinsic parameters to obtain the intrinsic and extrinsic parameters of each subsystem and the overall extrinsic parameters of the system. This mainly includes the following steps: For each measurement subsystem, a two-dimensional calibration plate with five large circles is used to accurately calibrate the intrinsic and extrinsic parameters of each unit based on the Zhang Zhengyou calibration method, for subsequent measurement of local three-dimensional deformation data; For the overall extrinsic parameters of the system, high-precision three-dimensional coordinate information of all marker points on the surface of the calibration object is obtained in advance using methods such as photogrammetry, serving as a reference marker point group. Then, based on the coordinates of the local marker points measured by each subsystem, they are sequentially registered with the reference marker point group to obtain the extrinsic parameter relationships between the subsystems. The calibration object can be any object with different characteristics, such as a cylinder or rectangular block; simply attach marker points at different positions on it.

[0054] Example 3

[0055] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0056] Example 4

[0057] According to another aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0058] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of acquiring information of a three-dimensional deformation field of a structure, characterized by, The method comprises the following steps: S1: acquiring deformation process data of a measured component carrying a speckle pattern from different perspectives to extract local deformation data corresponding to each perspective and splice the local deformation data to obtain an initial splicing result; S2: judging whether there is an overlapping part in the initial splicing result; S3: if there is an overlapping part, iteratively optimizing the initial splicing result until an optimal rigid transformation matrix between each local deformation data is found, and taking the current optimized splicing result as a fine splicing result; S4: performing continuity verification on the fine splicing result; S5: performing smoothing processing and down-sampling on the fine splicing result that passes the verification to obtain three-dimensional deformation field information of the measured component; The down-sampling in S5 comprises the following steps:

2. The method of claim 1, wherein S5.2 comprises: Using the formula Assign a weight to each point in the grid, and select the point with the maximum weight as the representative point; wherein, represents the weight of the point, C represents the cross-correlation coefficient when the point is deformed, represents the relative distance of the point from the center of gravity.

3. The method of claim 1, wherein the method further comprises: S5.1: calculating a bounding box of the overlapping part in the fine splicing result that passes the verification and has been subjected to smoothing processing, and discretizing the bounding box into a plurality of squares; S5.2: assigning a weight to each point in the square according to a correlation coefficient of the point in deformation calculation and a distance of the point from a center of gravity of the square, and selecting a point with a maximum weight as a representative point; 4. The method of acquiring a three-dimensional deformation field information of a structure according to any one of claims 1 to 3, wherein S5.3: representing the bounding box by using the representative points of all squares to obtain the three-dimensional deformation field information of the measured component. The S1 comprises the following steps: acquiring deformation process data of a measured component carrying a speckle pattern from different perspectives by using different measurement sub-systems that have been calibrated, to extract local deformation data corresponding to each perspective; and converting the local deformation data to the same coordinate system as an initial splicing result.

5. A device for acquiring three-dimensional deformation field information of a component, characterized in that, After the S2, the method further comprises the following steps: if there is no overlapping part, performing continuity verification on the initial splicing result; performing smoothing processing on the initial splicing result that passes the verification to obtain three-dimensional deformation field information of the measured component. The method comprises the following steps: a splicing module, configured to acquire deformation process data of a measured component carrying a speckle pattern from different perspectives to extract local deformation data corresponding to each perspective and splice the local deformation data to obtain an initial splicing result; a judging module, configured to judge whether there is an overlapping part in the initial splicing result; an optimizing module, configured to, if there is an overlapping part, iteratively optimize the initial splicing result until an optimal rigid transformation matrix between each local deformation data is found, and take the current optimized splicing result as a fine splicing result; a verifying module, configured to perform continuity verification on the fine splicing result; 6.An electronic device comprising a memory and a processor, the memory storing a computer program, wherein, a post-processing module, configured to perform smoothing processing and down-sampling on the fine splicing result that passes the verification to obtain three-dimensional deformation field information of the measured component; the down-sampling comprises the following steps: calculating a bounding box of the overlapping part in the fine splicing result that passes the verification and has been subjected to smoothing processing, and discretizing the bounding box into a plurality of squares; assigning a weight to each point in the square according to a correlation coefficient of the point in deformation calculation and a distance of the point from a center of gravity of the square, and selecting a point with a maximum weight as the representative point; and representing the bounding box by using the representative points of all squares to obtain the three-dimensional deformation field information of the measured component. The processor executes the computer program to implement the steps of the method in any one of claims 1 to 4.

7. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program, which is executed by a processor, implements the steps of the method according to any one of claims 1 to 4.

Images