Irregular curved surface laser scribing robot positioning method and device

Abstract

The invention discloses an irregular curved surface laser scribing robot positioning method and device, and relates to the field of robot positioning, and the method comprises the steps: extracting feature points of an irregular curved surface workpiece based on profile point cloud data, and obtaining an actually measured feature point set; on the basis of the actually measured feature point set, the preset lineation path and the irregular curved surface workpiece are matched; selecting coordinate point sets of an X axis and a Y axis of movement of the laser scribing robot on the XY plane mapping of the matched scribing path, and searching a coordinate point set of a corresponding Z axis to obtain a coordinate point set of the matched scribing path; determining a moving path point set of the laser scribing robot based on the matched coordinate point set of the scribing path; the laser scribing robot is controlled to move based on the moving path point set, and positioning of the laser scribing robot is achieved. According to the method, the laser scribing robot can adaptively plan the moving path along with the irregular curved surface, and the problems that a traditional scribing robot is low in programming efficiency and cannot accurately follow the scribing position are solved.

Description

Technical Field

[0001] This application relates to the field of robot positioning, and in particular to a method and apparatus for positioning a robot that performs laser marking on irregular curved surfaces. Background Technology

[0002] After machining irregular curved surfaces such as ship panel panels, structural lines need to be drawn on the surface for allowance cutting and assembly welding. To ensure cutting and assembly accuracy, the spatial position of the structural lines must be accurately located. Currently, drawing lines on such irregular curved surfaces mainly uses the method of manually placing templates / sample boxes to determine key points and then connecting the lines. The measurement accuracy and consistency need to be improved.

[0003] Laser scribing robots offer high positioning accuracy, good consistency, and fine, durable scribing, and have become widely used in the cutting and marking of flat materials. However, scribing irregular curved surfaces requires the robot's actuator distance to vary with the surface, placing higher demands on robot positioning. Currently, most robots operate using a "teach-and-reproduce" mode, resulting in low programming efficiency, poor adaptability, and an inability to accurately follow the scribing position. Summary of the Invention

[0004] The purpose of this application is to provide a method and apparatus for positioning a robot that performs laser marking on irregular curved surfaces, which can control the robot to follow the marking position and perform laser marking to complete the marking operation.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] A method for locating a robot that performs laser marking on irregular curved surfaces includes:

[0007] Acquire the point cloud data of irregular curved surfaces;

[0008] Based on the surface point cloud data, feature points of irregular curved surface workpieces are extracted to obtain the measured feature point set;

[0009] Based on the measured feature point set, the preset scribing path and irregular curved surface workpiece are matched to obtain the matched scribing path.

[0010] Select the set of coordinate points for the X and Y axes of the laser marking robot's motion on the XY plane mapping of the matched marking path;

[0011] Find the corresponding set of coordinate points on the Z-axis based on the set of coordinate points on the X-axis and Y-axis, and obtain the set of coordinate points for the matched line path;

[0012] The set of points for the laser marking robot's movement path is determined based on the set of coordinate points of the matched marking path.

[0013] The laser marking robot is controlled to move based on the set of movement path points, thereby achieving the positioning of the laser marking robot.

[0014] Secondly, this application provides a positioning device for a robot that performs laser marking on irregular curved surfaces, comprising:

[0015] The laser 3D imaging measurement module is used to acquire the surface point cloud data of irregular curved workpieces;

[0016] A laser marking robot, equipped with a laser galvanometer at its end, is used to perform the marking action;

[0017] A computer is communicatively connected to the laser 3D imaging measurement module and the laser marking robot, and is used to execute the above-described irregular surface laser marking robot positioning method.

[0018] According to the specific embodiments provided in this application, this application has the following technical effects:

[0019] This application provides a positioning method and apparatus for a laser scribing robot on irregular curved surfaces. By matching a preset scribing path with an irregular curved workpiece, the movement path point set of the laser scribing robot is determined, realizing the adaptive planning of the movement path of the laser scribing robot with the irregular curved surface. This solves the problems of low programming efficiency and inability to accurately follow the scribing position of traditional scribing robots, and is applicable to most curved surface scribing scenarios. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart illustrating a method for locating a robot using laser marking on an irregular curved surface, as provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram illustrating the matching of a preset line path with an irregular curved surface.

[0023] Figure 3 A schematic diagram of the coordinate points set along the X and Y axes for the motion of a laser marking robot;

[0024] Figure 4 This is a schematic diagram of the coordinate point set of the matched line path;

[0025] Figure 5 A schematic diagram of the movement path point set of a laser marking robot;

[0026] Figure 6 This is a schematic diagram of the positioning device for a laser marking robot on an irregular curved surface. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] In one exemplary embodiment, such as Figure 1 As shown, a method for locating a robot using laser marking on an irregular curved surface is provided. This method is executed by a computer device, specifically by a terminal or server alone, or by both a terminal and a server. In this embodiment, the method is described using a server as an example, and includes the following steps S1 to S7.

[0030] S1: Obtain the surface point cloud data of the irregular curved surface workpiece.

[0031] Specifically, a laser 3D imaging measurement module is used to acquire point cloud data of irregular curved surface workpieces.

[0032] S2: Based on the surface point cloud data, extract feature points of the irregular curved surface workpiece to obtain a measured feature point set. Specifically, this includes: determining edge feature points based on the change in the normal angle of each point in the surface point cloud data; determining edge corner points based on the edge feature points to obtain a feature point set of the irregular curved surface workpiece.

[0033] The specific process is as follows:

[0034] (1) Calculate the normals of each point in the surface point cloud data using software (such as cloudcompare).

[0035] (2) Extract edge feature points of irregular curved surfaces by judging the changes in the included angle of the normals at each point. Set the included angle threshold θ. e If the angle between the normals Then the point is considered an edge feature point, where a ij For point p i Its neighboring point p ij The angle between the normals and the boundary, where k is the number of neighborhood points.

[0036] (3) Obtain the coordinates of corner points by identifying the corner points of the edge lines. Set a threshold θ for the angle between the edge feature points and adjacent points. c If point p on the edge i With adjacent point p j ,p k The included angle θ i <θ c Then p i The points are the corner points of the edge lines. Let the set of corner points be P = {p1, p2, ..., p...} n}, thus obtaining the measured feature point set of the irregular curved surface workpiece.

[0037] S3: Based on the measured feature point set, match the preset scribing path and irregular curved surface workpiece to obtain the matched scribing path; Figure 2 This is a schematic diagram illustrating the matching of a preset line path with an irregular curved surface.

[0038] This embodiment preferably uses point-to-point matching combined with the ICP algorithm to complete the matching. Specifically, it includes the following steps:

[0039] (1) Obtain the theoretical feature point set Q = {q1, q2, ..., q} of the preset line drawing path. n}

[0040] (2) The measured feature point set and the theoretical feature point set are matched by nearest point search or feature matching to determine the matching point pair.

[0041] Find the corresponding point pairs (p1, q1), (p2, q2), ..., (p1, q1), by nearest-neighbor search or feature matching. n ,q n ).

[0042] The nearest point search method is as follows: for each point p in the source point cloud (i.e., the set of measured feature points)... i Search for the nearest point q in the target point cloud (i.e., the theoretical feature point set). i As a corresponding point (e.g., to accelerate the search using a kd-tree).

[0043] The feature matching method is as follows: first, extract local features of the point cloud (such as FPFH and SHOT features), and then match corresponding points through feature similarity (to reduce false matches).

[0044] (3) Calculate the optimal rigid transformation of the matching point pair; the optimal rigid transformation includes the rotation matrix and the translation vector.

[0045] Calculate the centroids of the source and target point clouds: and

[0046] Based on the centroids of the theoretical feature point set and the measured feature point set, the theoretical feature point set and the measured feature point set are respectively decentered to obtain a decentered vector: and

[0047] Construct a covariance matrix based on the decentralized vector. And perform singular value decomposition H = UΣV T , where U and V are orthogonal matrices, and Σ is a diagonal matrix.

[0048] Calculate the rotation matrix based on the orthogonal matrix: R = VU T .

[0049] Calculate the translation vector based on the rotation matrix:

[0050] (4) Based on the optimal rigidity transformation, the theoretical feature point set is matched to the irregular curved surface workpiece to obtain the matched scribing path.

[0051] The transformation T(R,t) obtained in the previous step is applied to the theoretical feature point set Q, and the registration error is estimated. Root mean square error. Average distance

[0052] Repeat steps (3) and (4) until the stopping condition, such as the maximum number of iterations, is met.

[0053] S4: Select the set of coordinate points for the X and Y axes of the laser marking robot's motion on the XY plane mapping of the matched marking path.

[0054] like Figure 3 As shown, based on the working plane range of the laser galvanometer for marking lines, a set of X,Y coordinate points [(x1,y1),(x2,y2),…] is selected on the XY plane mapping of the matched marking path for the robot's motion. When the selected point exceeds the matched marking path, the endpoint of the path is selected.

[0055] S5: Based on the coordinate point set of the X-axis and Y-axis, find the corresponding coordinate point set of the Z-axis to obtain the coordinate point set of the matched line path.

[0056] like Figure 4 As shown, based on the X and Y coordinates of the X and Y coordinate point set, the corresponding Z coordinate is found, resulting in the coordinate point set P2 = [(x1,y1,z1),(x2,y2,z3),...].

[0057] S6: Determine the movement path point set of the laser marking robot based on the coordinate point set of the matched marking path. Specifically, determine the working distance of the marking laser galvanometer installed at the end of the laser marking robot; offset the Z-axis coordinate of the coordinate point set of the matched marking path according to the working distance of the marking laser galvanometer to obtain the movement path point set of the laser marking robot.

[0058] like Figure 5 As shown, based on the working distance h of the laser galvanometer for marking lines, the coordinate point set of the laser marking robot tool is obtained by offsetting the Z value of the marking path corresponding to the coordinate point set P2 by a hovering height, which is the moving path point set of the laser marking robot: P'2=[(x'1,y'1,z'1),(x'2,y'2,z'3),…]=[(x1,y1,z1-h),(x2,y2,z3-h),…].

[0059] S7: Control the movement of the laser marking robot based on the set of movement path points to achieve the positioning of the laser marking robot.

[0060] The laser marking robot and laser are controlled by software to move according to the point set P'2 to complete the marking.

[0061] This application enables laser marking robots to adaptively plan their hovering height and movement path according to the surface to be processed, solving the problems of low programming efficiency and inability to accurately follow the marking position of traditional marking robots, and is applicable to most curved surface marking scenarios.

[0062] Based on the same inventive concept, this application also provides a positioning device for a robot that performs laser marking on irregular surfaces. The solution provided by this system is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the positioning device for a robot that performs laser marking on irregular surfaces provided below can be found in the limitations of the positioning method for a robot that performs laser marking on irregular surfaces above, and will not be repeated here.

[0063] In one exemplary embodiment, such as Figure 6 As shown, a positioning device for a robot that performs laser marking on irregular curved surfaces is provided, comprising:

[0064] A laser 3D imaging measurement module is used to acquire point cloud data of irregular curved surface workpieces. The laser 3D imaging measurement module is suspended and shoots downwards, and its imaging area covers the scribing area of ​​the irregular curved surface workpiece.

[0065] A laser scribing robot is equipped with a scribing laser galvanometer at its end effector to perform scribing actions. The laser scribing robot is mounted either overhead or side-mounted, and the processing distance and range of the scribing laser galvanometer cover the scribing area of ​​irregular curved workpieces.

[0066] A computer is communicatively connected to the laser 3D imaging measurement module and the laser marking robot, and is used to execute the irregular curved surface laser marking robot positioning method described above.

[0067] The laser 3D imaging measurement module and the laser marking robot are fixedly installed on the same gantry bracket to ensure that the structure does not deform during the measurement and marking process.

[0068] The laser 3D imaging measurement module uses a suspended mounting method to take downward images, and the installation position ensures that the irregular curved surface to be marked can be captured. The laser marking robot is suspended or side-mounted, with a marking laser galvanometer fixed at its end. The installation position ensures that the processing distance and range of the marking laser can cover the irregular curved surface to be marked, and that it does not affect the measurement of the laser 3D imaging measurement module when retracted.

[0069] Before using the above device, it is necessary to use the hand-eye calibration procedure provided by the laser scribing robot to unify the measurement coordinates of the laser 3D imaging measurement module with the tool coordinates of the laser scribing robot. Then, place the irregular curved workpiece in the laser scribing area to ensure that the workpiece is within the effective working range of the laser 3D imaging measurement module and the laser scribing robot.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for locating a robot using laser marking on irregular curved surfaces, characterized in that, include: Acquire the point cloud data of irregular curved surfaces; Based on the surface point cloud data, feature points of irregular curved surface workpieces are extracted to obtain the measured feature point set; Based on the measured feature point set, the preset scribing path and irregular curved surface workpiece are matched to obtain the matched scribing path. Select the set of coordinate points for the X and Y axes of the laser marking robot's motion on the XY plane mapping of the matched marking path; Find the corresponding set of coordinate points on the Z-axis based on the set of coordinate points on the X-axis and Y-axis, and obtain the set of coordinate points for the matched line path; The set of points for the laser marking robot's movement path is determined based on the set of coordinate points of the matched marking path. The laser marking robot is controlled to move based on the set of movement path points, thereby achieving the positioning of the laser marking robot.

2. The method for positioning a robot using laser marking on irregular curved surfaces according to claim 1, characterized in that, Based on the surface point cloud data, the measured feature point set of the irregular curved surface workpiece is extracted, specifically including: Edge feature points are determined based on the changes in the included angle of the normals at each point in the surface point cloud data. Based on the edge feature points, the corner points of the edge lines are determined, and the set of measured feature points of the irregular curved surface workpiece is obtained.

3. The method for positioning a robot using laser marking on irregular curved surfaces according to claim 1, characterized in that, Based on the aforementioned feature points and the measured set of feature points, a pre-defined scribing path and an irregular curved surface workpiece are matched to obtain the matched scribing path, specifically including: Obtain the theoretical feature point set of the preset line drawing path; The measured feature point set and the theoretical feature point set are matched using nearest point search or feature matching to determine matching point pairs; Calculate the optimal rigid transformation of the matching point pair; the optimal rigid transformation includes a rotation matrix and a translation vector; Based on the optimal rigidity transformation, the theoretical feature point set is matched onto the irregular curved surface workpiece to obtain the matched scribing path.

4. The method for positioning a robot with a laser marking system on an irregular curved surface according to claim 3, characterized in that, Calculating the optimal stiffness transformation of the matching point pair specifically includes: Calculate the centroids of the theoretical feature point set and the measured feature point set, respectively; Based on the centroids of the theoretical feature point set and the measured feature point set, the theoretical feature point set and the measured feature point set are respectively decentered to obtain a decentered vector; A covariance matrix is ​​constructed based on the decentralized vector, and singular value decomposition is performed on the covariance matrix to obtain an orthogonal matrix. Calculate the rotation matrix based on the orthogonal matrix; The translation vector is calculated based on the rotation matrix.

5. The method for positioning a robot with a laser marking system on an irregular curved surface according to claim 1, characterized in that, When selecting the set of coordinate points for the X and Y axes of the laser marking robot's motion on the XY plane mapping of the matched marking path, if the selected points exceed the matched marking path, the endpoint of the matched marking path is selected.

6. The method for positioning a robot with a laser marking system on an irregular curved surface according to claim 1, characterized in that, The set of points for the laser marking robot's movement path is determined based on the set of coordinate points of the matched marking path, specifically including: Determine the working distance of the laser marking laser galvanometer installed at the end of the laser marking robot; The Z-axis coordinate of the matched marking path coordinate point set is offset according to the working distance of the marking laser galvanometer to obtain the moving path point set of the laser marking robot.

7. A positioning device for a robot that performs laser marking on irregular curved surfaces, characterized in that, The device includes: The laser 3D imaging measurement module is used to acquire the surface point cloud data of irregular curved workpieces; A laser marking robot, equipped with a laser galvanometer at its end, is used to perform the marking action; A computer, communicatively connected to the laser three-dimensional imaging measurement module and the laser marking robot, is used to execute the irregular curved surface laser marking robot positioning method as described in any one of claims 1 to 6.

8. The positioning device for a robot that performs laser marking on irregular curved surfaces according to claim 7, characterized in that, The laser 3D imaging measurement module and the laser marking robot are fixedly mounted on the same gantry bracket.

9. The positioning device for a robot with an irregular curved surface laser marking according to claim 7, characterized in that, The laser three-dimensional imaging measurement module is suspended and takes downward images, and the imaging area of ​​the laser three-dimensional imaging measurement module covers the scribing area of ​​the irregular curved surface workpiece.

10. The positioning device for a robot with an irregular curved surface laser marking according to claim 7, characterized in that, The laser scribing robot is mounted by suspension or side mounting, and the processing distance and range of the scribing laser galvanometer cover the scribing area of ​​irregular curved workpieces.

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