Ultrasonic profiling scanning method and system for special-shaped structures based on calibration of lifting paths

Abstract

The present invention discloses a method and system for ultrasonic profiling scanning of special-shaped structures based on lifting path calibration. The present invention can intelligently identify the complex scanning surface of a workpiece and dynamically generate and adjust the scanning path, and uses machine vision to guide a robotic arm to clamp an ultrasonic probe to complete the non-destructive testing of special-shaped workpieces, solving the ultrasonic testing problems of various special-shaped workpieces, improving the accuracy and efficiency of ultrasonic testing of special-shaped workpieces. By connecting the ultrasonic probe to the robotic arm, it ensures that the probe can accurately scan the detection points while also ensuring the precise and controllable movement of the detection points, enhancing the applicability of the detection of workpieces with complex morphologies and the freedom of the scanning path; at the same time, it can greatly improve the detection efficiency of workpieces, and it is expected to apply this method to the on-site detection of workpieces, solving the problems of difficult detection, low detection efficiency and large error of special-shaped structure workpieces.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial automation ultrasonic testing, in particular to the technical field of an ultrasonic profiling scanning method and system for water immersion full focusing of special-shaped structures based on calibration of lifting paths. Background Art

[0002] In the field of industrial automation ultrasonic testing, the water immersion coupling method has excellent acoustic coupling ability, is less affected by clutter interference, has strong applicability to workpieces of different shapes and sizes, and has the prominent advantages of simple operation process, making this coupling method widely used in industrial testing. At present, it is often applied to the automated scanning technology of standard parts, and cannot autonomously adapt to the complex contours of non-standard parts, and still relies on CAD drawings and pre-set paths for the mechanical coordinate system. In theory, the above method can provide an effective detection path for standard parts, but in practical applications, the application of this method is limited due to geometric deviations and installation errors of non-standard parts.

[0003] These challenges mainly stem from two core problems: the installation error of the workpiece at the detection station and the complex scanning surface of the workpiece itself. The installation error is usually caused by the unevenness of the support tooling or the fitting error between the workpiece and the tooling, resulting in a deviation between the actual position and the expected position of the workpiece. In addition, the complex scanning surface of the workpiece, such as variable curved surfaces, irregular contours, and local features, further increases the complexity of the detection path planning. The pre-set path cannot flexibly adapt to the complexity of the actual workpiece and the minor changes during the installation process, resulting in possible omission or uneven coverage of key areas during the detection process, thus affecting the accuracy and reliability of the detection. In view of the above problems, there is an urgent need for a water immersion ultrasonic detection system that can adapt to installation errors and complex scanning surfaces in the detection of non-standard parts, and provide an efficient and accurate non-destructive testing method for evaluating the internal quality of special-shaped workpieces. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art, and propose an ultrasonic profiling scanning method and system for special-shaped structures based on calibration of lifting paths, which can intelligently identify the complex scanning surface of the workpiece and dynamically generate and adjust the scanning path to improve the accuracy and efficiency of ultrasonic testing of special-shaped workpieces.

[0005] To achieve the above purpose, the present invention proposes an ultrasonic profiling scanning method for special-shaped structures based on calibration of lifting paths, including a lifting device for carrying the workpiece and moving along a set path; a robotic arm; an ultrasonic probe installed at the end of the robotic arm; a water tank; a structured light 3D camera; including:

[0006] Step S1, set a number of marking points on the lifting device. The marking points are installed within the field of view of the structured light 3D camera. With no water in the water tank, raise the lifting device to the highest point. Obtain the spatial coordinates of multiple marking points at different heights through the structured light 3D camera, calculate the coordinate transformation at different positions, and fit to obtain the lifting path calibration formula related to the lifting stroke.

[0007] Step S2, inject enough water into the water tank so that the workpiece can be completely immersed. Lift the workpiece above the water surface and obtain the point cloud data of the special-shaped surface of the workpiece through the structured light 3D camera. Crop the collected point cloud data to determine the detection area and identify the data boundary. Plan the detection path and the robot end pose control process according to the requirements of the water immersion full-focus ultrasonic testing process parameters.

[0008] Step S3, control the lifting device to immerse the workpiece into the water tank, record the descending distance, and update the detection path and the robot end pose control process through the lifting path calibration formula.

[0009] Step S4, issue a detection task to the controller carried by the robot arm and the robot end pose solution module. The robot end pose solution module sets the detection instrument synchronization parameters according to the path planning result. While the detection instrument completes the detection task, it transmits the detection data in real time for subsequent processing.

[0010] Step S5, repeat Step S4 until the focus of the ultrasonic probe traverses all the specified points in the path planning.

[0011] Preferably, four marking points are set on the lifting device in Step S1, which are located on the four sides of the lifting device respectively.

[0012] Preferably, Step S2 includes:

[0013] Step S2-1, point cloud preprocessing. Denoise the original point cloud data using a Gaussian filter to reduce the noise points generated during the scanning process.

[0014] Step S2-2, point cloud cropping. Use an octree data structure to perform spatial segmentation on the point cloud, quickly locate the detection area of the workpiece, and crop the point cloud data: P′ = Clip(P, AABB), where P′ is the cropped point cloud, P is the original point cloud, and AABB is the axis-aligned bounding box of the workpiece detection area.

[0015] Step S2-3, workpiece feature recognition. Use the classic region growing algorithm to perform point cloud segmentation, identify the key feature parts of the workpiece, and expand the region from the seed points according to the local geometric features of the point cloud until the preset similarity threshold is met.

[0016] Step S2-4, Detection Area and Boundary Determination: Based on the feature recognition result, determine the detection area of the workpiece and calculate the boundary of the detection area.

[0017] Preferably, step S2-3 includes:

[0018] Step S2-3.1, Normal Vector Calculation and Segmentation: First, calculate the normal vector of each point, and use the principal component analysis method to estimate the normal vector of the point cloud. Then, according to the similarity of the normal vectors, perform clustering and segmentation of the point cloud, and classify the points with similar normal vectors into the same category;

[0019] Step S2-3.2, Feature Point Extraction: Based on the region growing segmentation result, extract feature points with high distinctiveness. These feature points will serve as the key areas for subsequent detection and analysis to ensure the accurate recognition of the surface morphology of the workpiece.

[0020] Preferably, the feature points include sharp edges, local convex or concave regions.

[0021] Preferably, in step S2-4, the boundary is determined using the minimum bounding rectangle method. This method generates a minimum rectangular bounding region based on the coordinates of the feature points on the workpiece surface to ensure that the path during the scanning process covers all target areas.

[0022] Preferably, in step S1, raise the lifting table completely to the highest point, use the structured light 3D camera facing the workpiece to take a photo, obtain the spatial coordinates of the marking points at this time, control the lifting device to descend, and use the structured light 3D camera to take photos at the 1 / 4, 1 / 2, and 3 / 4 stroke positions respectively to obtain the spatial coordinates of the marking points at the corresponding positions.

[0023] Preferably, step S1 includes: Step S1-1, Obtain the Spatial Coordinates of the Marking Points: Use the structured light 3D camera to photograph the marking point cluster and obtain the spatial coordinates of each marking point at the highest point and the target height For each marking point at height the coordinate is , at height the coordinate is ;

[0024] Step S1-2, Calculate the Centroid and Align: Calculate the centroid of the marking point cluster at different heights to obtain the corresponding translation vector:

[0025] At height the centroid : ,

[0026] At height The centroid at : ;

[0027] Step S1-3, using the centroid difference to calculate the translation vector:

[0028] ;

[0029] Then align the marker point coordinates to the centroid reference system, that is, remove the translation part, to obtain the centroidal coordinates:

[0030] ;

[0031] ;

[0032] Calculate the rotation difference, using the centroidal marker point coordinates, calculate the rotation matrix R;

[0033] Construct the covariance matrix :

[0034] ;

[0035] Through the covariance matrix perform singular value decomposition to obtain the orthogonal matrices and :

[0036] ;

[0037] Calculate the rotation matrix :

[0038] ;

[0039] Step S1-5, fit the lifting path calibration formula, at different heights record the rotation matrix of the lifting platform and the translation vector , and use the linear formula to fit the functions varying with and ;

[0040] ;

[0041] ;

[0042] where is the initial rotation matrix, is the initial translation vector, , are the fitting coefficient matrices;

[0043] Step S1-6: Apply translation and rotation to calibrate the surface point cloud coordinates of the workpiece in water immersion, and obtain the surface scan coordinates of the workpiece at the highest point. After that, the obtained translation vector and rotation matrix are applied to any target height, so as to obtain the calibrated The water immersion scan coordinates at the position are .

[0044] Another object of the present invention is to provide a special-shaped structure ultrasonic profiling scanning system based on lifting path calibration, including:

[0045] A lifting device for carrying the workpiece and moving along a set path;

[0046] A robotic arm for controlling the movement of the ultrasonic probe according to the planned path;

[0047] An ultrasonic probe for emitting and receiving ultrasonic signals, which is installed at the end of the robotic arm;

[0048] An ultrasonic imaging module for collecting, processing ultrasonic signals and generating high-resolution ultrasonic imaging;

[0049] A control module for controlling the robotic arm to perform scanning along the surface of the workpiece and adjusting the posture of the ultrasonic probe on the robotic arm according to the pre-calibrated path;

[0050] A water tank for providing a liquid immersion environment to ensure that the workpiece is completely immersed in the liquid during ultrasonic scanning;

[0051] A structured light 3D camera for obtaining the surface point cloud information of the workpiece and calibrating the lifting path; a main control computer, which is connected to the structured light 3D camera, the robotic arm, and the ultrasonic probe;

[0052] A data processing module for processing the data collected from the structured light 3D camera and the full-focus ultrasonic imaging module, and performing scanning path planning and full-focus ultrasonic imaging.

[0053] Preferably, the lifting device includes a vertically arranged lifting driver and a load platform horizontally arranged on the lifting driver.

[0054] Preferably, the robotic arm is a robotic arm with six or more degrees of freedom.

[0055] Beneficial effects of the method and system for ultrasonic profiling scanning of special-shaped structures based on lifting path calibration: The present invention can intelligently identify the complex scanning surface of a workpiece and dynamically generate and adjust the scanning path. It uses machine vision to guide a robotic arm to hold an ultrasonic probe to complete the non-destructive testing of special-shaped workpieces, solving the ultrasonic testing problems of various special-shaped workpieces, improving the accuracy and efficiency of ultrasonic testing of special-shaped workpieces. By connecting the ultrasonic probe to the robotic arm, it ensures that the ultrasonic probe can accurately scan the detection points while also ensuring the precise and controllable movement of the detection points, enhancing the applicability of detecting workpieces with complex shapes and the freedom of the scanning path. At the same time, it can greatly improve the detection efficiency of workpieces and is expected to apply this method to on-site detection of workpieces, solving the problems of difficult detection, low detection efficiency, and large errors of special-shaped structure workpieces.

[0056] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. Brief Description of the Drawings

[0057] Figure 1 is a schematic structural diagram of the system for ultrasonic profiling scanning of special-shaped structures based on lifting path calibration of the present invention.

[0058] In the figure: 1 - robotic arm, 2 - ultrasonic probe, 3 - lifting drive, 4 - structured light 3D camera, 5 - carrier table, 6 - workpiece, 7 - water tank. Detailed Embodiments

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0060] In the description of the present invention, it should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0061] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0062] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] Example 1:

[0064] Refer to Figure 1, an ultrasonic profiling scanning system for special-shaped structures based on lifting path calibration according to the present invention includes a six-degree-of-freedom robotic arm 1, a full-focus ultrasonic probe 2, a full-focus ultrasonic detector, a lifting device, a structured light 3D camera 4, a stage 5, a workpiece 6 with a special shape to be inspected, a water tank 7, a main control computer, a full-focus ultrasonic detection instrument, and a robotic arm control box; among them, the lifting device includes a lifting driver 3 and a stage 5, the lifting driver 3 is used to drive the stage 5 to move up and down, the full-focus ultrasonic probe 2 is installed at the end of the six-degree-of-freedom robotic arm 1, and the full-focus ultrasonic probe 2 is water-coupled with the workpiece 6. The structured light 3D camera 4 is fixed on the extension arm above the lifting driver 3, the workpiece 6 is placed on the stage below the lifting driver 3, the main control computer is connected to the structured light 3D camera 4, the robotic arm control box, and the full-focus ultrasonic detector, and the main control computer is built with a data processing module for processing the data collected from the structured light 3D camera and the full-focus ultrasonic imaging module, and for performing scanning path planning and full-focus ultrasonic imaging. By connecting the full-focus ultrasonic probe to a six-degree-of-freedom robotic arm, it is ensured that the ultrasonic probe can accurately scan the detection points while also ensuring the precisely controllable movement of the detection points, enhancing the applicability of detecting workpieces with complex shapes and the freedom of the scanning path; at the same time, using this device can greatly improve the detection efficiency of workpieces, and it is expected to apply this method to on-site detection of workpieces, solving the problems of difficult detection, low detection efficiency, and large errors of workpieces with special-shaped structures.

[0065] Embodiment 2:

[0066] Refer to Figure 1 , based on Embodiment 1, the ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to the present invention includes the following steps: Step S1, coordinate calibration. Four marking points are set on the lifting device, and the four marking points are respectively set at the four corner positions of the stage 5. The marking points are installed within the field of view of the structured light 3D camera 4. When there is no water in the water tank 7, the lifting device is raised to the highest point, and the spatial coordinates of the multiple marking points at different heights are obtained through the structured light 3D camera, and the coordinate transformation at different positions is calculated, and the lifting path calibration formula related to the lifting stroke is fitted; specifically including:

[0067] Step S1-1, obtaining the spatial coordinates of the marking points. Use the structured light 3D camera to photograph the marking point cluster, and obtain the spatial coordinates of each marking point at the highest point and the target height . For each marking point at height , the coordinate is , and at height , the coordinate is ;

[0068] Step S1-2: Calculate the centroid and align. Calculate the centroid of the marked point clusters at different heights to obtain the corresponding translation vectors:

[0069] The centroid at height : : ;

[0070] The centroid at height : : ;

[0071] Step S1-3: Use the centroid difference to calculate the translation vector:

[0072] ;

[0073] Then align the marked point coordinates to the centroid reference system, that is, remove the translation part to obtain the centroid-centered coordinates:

[0074] ;

[0075] ;

[0076] Calculate the rotation difference. Use the centroid-centered marked point coordinates to calculate the rotation matrix R;

[0077] Construct the covariance matrix :

[0078] ;

[0079] Perform singular value decomposition through the covariance matrix to obtain the orthogonal matrices and :

[0080] ;

[0081] Calculate the rotation matrix : ;

[0082] Step S1-5: Fit the lifting path calibration formula. At different heights such as 1 / 4, 1 / 2, 3 / 4 stroke, record the rotation matrix and the translation vector , and use the linear formula to fit the functions varying with and ;

[0083] ;

[0084] ;

[0085] where is the initial rotation matrix, is the initial translation vector, and is the fitting coefficient matrix;

[0086] Step S1-6, applying translation and rotation to calibrate the surface point cloud coordinates of the workpiece in water immersion. In actual inspection, the surface scan coordinates of the workpiece at the highest point are obtained After that, the fitting translation vector and the rotation matrix can be applied to any target height, so as to obtain the calibrated The water immersion scan coordinates at the position are .

[0087] Step S2, 3D data acquisition and processing. Inject enough water into the water tank 7 so that the workpiece can be completely immersed. Use the lifting driver 3 to drive the stage 5 to rise, lift the workpiece 6 above the water surface, and obtain the point cloud data of the special-shaped surface of the workpiece through the structured light 3D camera 4, and obtain the depth and position information of the workpiece. The resolution of the cloud data acquisition is 0.05 mm, which ensures the high-precision capture of the surface features of the workpiece. Crop the collected point cloud data to determine the detection area and identify the data boundary. On this basis, plan the detection path and the robotic arm end attitude control process according to the requirements of the water immersion full-focus ultrasonic testing process parameters; specifically including:

[0088] Step S2-1, point cloud preprocessing. Denoise the original point cloud data, using a Gaussian filter to reduce the noise points generated during the scanning process; Step S2-2, point cloud cropping. Use an octree data structure to perform spatial segmentation on the point cloud, quickly locate the detection area of the workpiece, and crop the point cloud data: P′ = Clip(P, AABB), where P′ is the cropped point cloud, P is the original point cloud, and AABB is the axis-aligned bounding box of the workpiece detection area; Step S2-3, workpiece feature recognition. Use the classic region growing algorithm to perform point cloud segmentation, identify the key feature parts of the workpiece, and expand the region from the seed points according to the local geometric features of the point cloud until the preset similarity threshold is met;

[0089] Step S2-3.1, normal vector calculation and segmentation. First, calculate the normal vector of each point, using the PCA principal component analysis method to estimate the normal vector of the point cloud. Then, according to the similarity of the normal vectors, perform point cloud clustering and segmentation, and classify the points with similar normal vectors into the same class;

[0090] Step S2-3.2, Feature Point Extraction: Based on the region growing segmentation result, extract feature points with high distinctiveness, such as sharp edges, local convex or concave regions, etc. These feature points will serve as key regions for subsequent detection and analysis to ensure accurate recognition of the workpiece surface morphology;

[0091] Step S2-4, Detection Region and Boundary Determination: According to the feature recognition result, determine the detection region of the workpiece and calculate the boundary of the detection region. The boundary is determined using the minimum bounding rectangle method, which generates a minimum rectangular enclosing region based on the coordinates of the feature points on the workpiece surface to ensure that the scanning path covers all target regions. Step S3, Path Planning and Pose Control: Control the lifting device to immerse the workpiece into the water tank 7, record the descending distance, and update the detection path and the pose control process of the end of the robotic arm 1 through the lifting path calibration formula obtained in Step S1-6;

[0092] Step S4, The main control computer issues a detection task to the controller carried inside the robotic arm 1 and the robot end pose solution module. The robot end pose solution module sets the detection instrument synchronization parameters according to the path planning result, including the detection method, detection mode, detection accuracy, and trigger frequency, to ensure that the ultrasonic probe is always aligned with the normal line. While the detection instrument completes the detection task, it transmits the detection data in real time for subsequent processing.

[0093] Step S5, Repeat Step S4 until the focus of the ultrasonic probe traverses all specified points in the path planning.

[0094] In summary, the present invention uses machine vision to guide the robotic arm to hold the ultrasonic probe to complete the non-destructive testing of special-shaped workpieces, specifically including detection path planning, adapting to the surface of the workpiece to be inspected, and high detection efficiency, etc.

[0095] It should be noted that although the above embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, any changes and modifications to the embodiments described in this article, or equivalent structural or equivalent process transformations made using the content of the specification and drawings of the present invention, directly or indirectly applying the above technical solutions to other related technical fields, are all included in the protection scope of the present invention patent.

Claims

1. The ultrasonic profiling scanning method of special-shaped structures based on lifting path calibration is characterized by: It includes a lifting device for carrying the workpiece and moving it along a set path; Robotic arm; Ultrasonic probe, installed at the end of the robotic arm; Water tank; Structured light 3D camera; The method comprises: step S1, setting a plurality of marking points on the lifting device, wherein the marking points are installed within the field of view of the structured light 3D camera, raising the lifting device to the highest point when there is no water in the water tank, obtaining the spatial coordinates of the plurality of marking points at different heights through the structured light 3D camera, calculating the coordinate transformation at different positions, and fitting to obtain a lifting path calibration formula related to the lifting stroke; Step S1-1, obtain the spatial coordinates of the marker points, use a structured light 3D camera to shoot the marker point cluster, and and target height Get the spatial coordinates of each marker point at At height The coordinates of , at height The coordinates of ; Step S1-2, calculate the centroid and align, calculate the centroid of the marker clusters at different heights, and obtain the corresponding translation vector: At height The centroid of : , At height The centroid of : ; Step S1-3, using the centroid difference Calculate the translation vector: ； Then align the coordinates of the marker points to the centroid reference system, that is, remove the translation part to obtain the centroid coordinates: ； ； Step S1-4, calculating the rotation difference, and using the centroided marker point coordinates to calculate the rotation matrix R; Constructing the covariance matrix : ； Through the covariance matrix Perform singular value decomposition to obtain an orthogonal matrix and : ； Calculate the rotation matrix : ； Step S1-5, fitting the lifting path calibration formula, at different heights Next, record the rotation matrix of the lifting platform and translation vectors , and the linear formula can be used to fit the Function of change and ; ； ； Among them is The initial rotation matrix, is the initial translation vector, , is the fitting coefficient matrix; Step S1-6, applying translation and rotation to calibrate the surface point cloud coordinates of the workpiece in water immersion to obtain the surface scanning coordinates of the workpiece at the highest point Then, the fitted translation vector and the rotation matrix Applicable to any target height So as to obtain the calibrated The immersion scan coordinates at position are: ; Step S2, inject enough water into the water tank to fully immerse the workpiece, lift the workpiece above the water surface and obtain point cloud data of the workpiece's irregular surface through a structured light 3D camera, crop the collected point cloud data to determine the detection area, identify the data boundary, and plan the detection path and the end-of-arm posture control process according to the process parameter requirements of immersion fully focused ultrasonic testing; Step S3, controlling the lifting device to immerse the workpiece into the water tank, recording the descending distance, and updating the detection path and the robot end posture control process through the lifting path calibration formula; Step S4, issuing a detection task to the controller and the robot end posture solving module carried in the robot arm, and the robot end posture solving module sets the detection instrument synchronization parameters according to the path planning results. When the detection instrument completes the detection task, it transmits the detection data back in real time for subsequent processing; Step S5, repeating step S4 until the focus of the ultrasound probe traverses all designated locations in the path planning.

2. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 1, characterized in that: In the step S1, four marking points are set on the lifting device, respectively located on four sides of the lifting device.

3. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 1, characterized in that: The step S2 comprises: Step S2-1, point cloud preprocessing, denoising the original point cloud data, using a Gaussian filter to reduce the noise points generated during the scanning process; Step S2-2, point cloud clipping, use the octree data structure to perform spatial segmentation on the point cloud, quickly locate the detection area of ​​the workpiece, and clip the point cloud data: P′=Clip(P,AABB) where P′ is the clipped point cloud, P is the original point cloud, and AABB is the axis-aligned bounding box of the workpiece detection area; Step S2-3, workpiece feature recognition, using the classic region growing algorithm to segment the point cloud and identify the key feature parts of the workpiece. Starting from the seed point, the region is expanded according to the local geometric features of the point cloud until the preset similarity threshold is met; Step S2-4, detection area and boundary determination, according to the feature recognition results, determine the detection area of ​​the workpiece and calculate the boundary of the detection area.

4. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 3, characterized in that: The step S2-3 comprises: Step S2-3.1, normal vector calculation and segmentation, first, calculate the normal vector of each point, use the principal component analysis method to estimate the normal vector of the point cloud, then cluster and segment the point cloud according to the similarity of the normal vectors, and classify points with similar normal vectors into the same category; Step S2-3.2, feature point extraction, based on the region growing segmentation results, extract feature points with high discrimination. These feature points will serve as key areas for subsequent detection and analysis to ensure accurate recognition of the workpiece surface morphology.

5. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 4, characterized in that: The feature points include sharp edges, local protrusions or depressions.

6. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 3, characterized in that: The boundary in step S2-4 is determined by using the minimum circumscribed rectangle method, which generates a minimum rectangular enclosing area based on the coordinates of the feature points on the surface of the workpiece to ensure that the path during the scanning process covers all target areas.

7. The ultrasonic profiling scanning method for special-shaped structures based on lifting path calibration according to claim 1, characterized in that: In step S1, the lifting platform is fully raised to the highest point, and a structured light 3D camera placed facing the workpiece is used to take pictures to obtain the spatial coordinates of the marking points at this time, the lifting device is controlled to descend, and the structured light 3D camera is used to take pictures at 1 / 4, 1 / 2, and 3 / 4 of the stroke respectively to obtain the spatial coordinates of the marking points at the corresponding positions.

8. An ultrasonic profiling scanning system for special-shaped structures based on lifting path calibration for implementing the method described in any one of claims 1 to 7, characterized in that: include: A lifting device, used to carry the workpiece and move it along a set path; a robotic arm for controlling the movement of the ultrasound probe according to the planned path; The ultrasonic probe is used to transmit and receive ultrasonic signals and is installed at the end of the robotic arm; the ultrasonic imaging module is used to collect and process ultrasonic signals and generate high-resolution ultrasonic images; A control module, used to control the robot arm to perform scanning along the surface of the workpiece according to a pre-calibrated path, and to adjust the posture of the ultrasonic probe on the robot arm; A water tank is used to provide a liquid immersion environment to ensure that the workpiece is completely immersed in the liquid during ultrasonic scanning; Structured light 3D camera, used to obtain point cloud information on the workpiece surface and calibrate the lifting path; A main control computer connected to the structured light 3D camera, the robotic arm, and the ultrasonic probe; The data processing module is used to process the data collected from the structured light 3D camera and the fully focused ultrasonic imaging module, and perform scanning path planning and fully focused ultrasonic imaging.

9. The ultrasonic profiling scanning system for special-shaped structures based on lifting path calibration according to claim 8, characterized in that: The lowering device comprises a vertically arranged lifting drive and a loading platform laterally arranged on the lifting drive.

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