Complex curved surface carbon fiber material ultrasonic detection method and system based on mechanical arm

Abstract

The invention provides a complex curved surface carbon fiber material ultrasonic detection method and system based on a mechanical arm, and belongs to the field of nondestructive testing. The method comprises the steps of obtaining file data containing a complex curved surface, obtaining all triangular patch data of the complex curved surface through analysis, and constructing a model database; establishing a triangular patch association table according to a relationship among triangular patches in the model database, and extracting a feature curved surface; according to preset scanning precision, point location random selection is carried out on triangular patches in the feature curved surface, and scanning point cloud is generated; a scanning plane is determined through a simulated annealing algorithm, and the scanning point clouds are clustered and sorted; according to the clustered and sorted point clouds, an optimal scanning path is planned in combination with the energy consumption cost of the mechanical arm; and calculating the bottom surface thickness corresponding to each point in the scanning point cloud based on the scanning path, determining an echo generation position, and further determining damage information in the carbon fiber material. The damage detection of the internal defects of the complex curved surface carbon fiber material is realized.

Claims

1. A method for ultrasonic detection of complex curved carbon fiber materials based on a robotic arm, characterized in that: include: Obtain file data containing a complex surface, obtain all triangular facet data of the complex surface through parsing, and construct a model database; the model database includes edge, point, face, area, and area ratio data; According to the relationship between the edges and points of the triangular facets in the model database, a triangular facet association table is established, and the triangular facets are classified according to the preset angle threshold and area size to extract the characteristic surface; According to the preset scanning accuracy, randomly select points from each triangular facet in the extracted feature surface to generate a scanning point cloud; The scanning plane is determined by the simulated annealing algorithm, and the generated scanning point cloud is clustered and sorted according to the distance; Based on the clustered and sorted point cloud and the energy consumption cost of the robotic arm, the optimal scanning path is planned; The bottom surface thickness corresponding to each point in the scan point cloud is calculated based on the scanning path. The bottom surface thickness is used to determine the location of the bottom surface echo of the ultrasonic signal. The signal at the abnormal position is detected as a damage signal, thereby determining the damage information in the carbon fiber material.

2. The ultrasonic detection method for complex curved carbon fiber materials based on a robotic arm according to claim 1, characterized in that: Classify according to the preset angle threshold and area size, and the process of extracting feature surfaces is as follows: Determine whether two adjacent triangles belong to the same surface as follows: Where, f ij (θ) is the discriminant condition function established based on the angles of the two patches; S i 、S j are the areas of the triangles respectively; α is the angle threshold; θ is the angle between the triangles; f lim (S) is the area threshold limit function; Where λ is the area ratio threshold.

3. The ultrasonic detection method for complex curved carbon fiber materials based on a robotic arm according to claim 1, characterized in that: The process of generating the scan point cloud includes: Create images based on the constructed model database, and use the same color to represent the triangles located on the same feature surface; Take out the triangular facets contained in the characteristic surface in turn, and calculate the total area of ​​the triangular facets and the probability distribution function of each triangular facet by querying the model database; Generate a random array according to the required number of point clouds, traverse the random array through the probability distribution function, and replace the elements in the random array with the triangle patch serial numbers; Take out the triangular facets in the random array one by one, obtain the vertex coordinates of the triangular facets by querying the model database, and obtain the sampling points by linear interpolation of the vertex coordinates.

4. The ultrasonic detection method for complex curved carbon fiber materials based on a robotic arm according to claim 1, characterized in that: The process of determining the scanning plane through the simulated annealing algorithm and clustering and sorting the point cloud according to distance is as follows: Put the three-dimensional coordinates of the sampling points into a two-dimensional array, select the maximum and minimum values ​​through a sorting algorithm and construct the initial scanning plane; A simulated annealing algorithm is used to initialize the parameters of the constructed initial scanning plane, and the updated temperature is obtained through iteration. The parameters of the simulated annealing algorithm include: initial temperature, termination temperature, cooling rate, initial solution and objective function value. When the temperature drops to the termination temperature, the solution of the current vector is output; the segmentation distance is set according to the motion accuracy of the robotic arm to obtain the clustered and sorted point cloud.

5. The method for ultrasonic detection of complex curved carbon fiber materials based on a robotic arm according to claim 4, characterized in that: The process of obtaining the updated temperature through iteration is: Sequentially extract unit vectors from the initial solution, use the unit vectors as the initial solution, and generate new solutions by perturbing the initial solution; Calculate the objective function value under the current new solution condition and the probability of accepting the new solution; By generating a random number, determining whether to accept the new solution based on the relationship between the random number and the probability of accepting the new solution; Finally, the updated temperature is obtained through a cooling operation.

6. The method for ultrasonic detection of complex curved carbon fiber materials based on a robotic arm according to claim 1, characterized in that: Based on the clustered and sorted point cloud and the energy consumption cost of the robotic arm, the process of planning the optimal scanning path is as follows: Based on the mean value of the point cloud after clustering sorting, the point farthest from the center is used as the initial point of the robot arm movement; Based on the initial point, the coordinates of all points in the point cloud and the inverse of the normal vector of the triangle element are sequentially formed into the pose matrix of each point in the model space; the pose matrix and the rotation matrix Rot in the real space are combined. 4×4 By multiplying the rotation matrix according to the rules, the coordinates of each point in the point cloud in the world coordinate system are obtained; the inverse solution of the robotic arm can be used to calculate the movement angle of each axis of the six-axis robotic arm corresponding to each point in the point cloud; Set the consumption coefficient of each axis movement angle of the robot arm to solve the movement loss of the robot arm; The next movement position of the robot arm is determined based on the movement loss of the robot arm, and the movement trajectory of the robot arm at all points is calculated in a loop.

7. The method for ultrasonic detection of complex curved carbon fiber materials based on a robotic arm according to claim 1, characterized in that: The bottom surface thickness corresponding to each point in the scan point cloud is calculated based on the scan path. The bottom surface thickness is used to determine the location of the bottom surface echo of the ultrasonic signal. The signal at the abnormal location is detected as a damage signal, thereby determining the damage information in the carbon fiber material, including: Each point in the scanned point cloud is extended in the opposite direction of the normal direction of the triangle where it is located, and all the triangles in the file are traversed to find the intersection with the plane where the triangle is located. It is determined whether the intersection point is inside the triangle. If it is inside the triangle, the intersection point is the depth coordinate of the scanned point. The depth information of the scanned point can be obtained by calculating the distance between the two points. An amplitude threshold is set as the basis for damage judgment, and the waveform is restored through TCG calibration. The final waveform is obtained by plotting the depth information of the scanning point as the horizontal axis and the signal after waveform calibration as the vertical axis. The final waveform is compared with the amplitude threshold to determine whether there is damage.

8. A robotic arm-based ultrasonic detection system for complex curved carbon fiber materials, characterized by: include: The model database construction module is configured to: obtain file data containing complex surfaces, obtain all triangular facet data of the complex surfaces through parsing, and construct a model database; the model database includes edge, point, face, area, and area ratio data; The feature surface extraction module is configured to: establish a triangle face association table based on the relationship between the edges and points between the triangle faces in the model database, classify them according to a preset angle threshold and area size, and extract the feature surface; The scanning point cloud generation module is configured to: randomly select points from each triangular facet in the extracted feature surface according to a preset scanning accuracy to generate a scanning point cloud; The clustering and sorting module is configured to: determine the scanning plane by a simulated annealing algorithm, and cluster and sort the generated scan point cloud according to distance; The optimal path planning module is configured to plan the optimal scanning path based on the clustered and sorted point cloud and the energy consumption cost of the robotic arm; The damage judgment module is configured to calculate the bottom surface thickness corresponding to each point in the scan point cloud based on the scan path, determine the location of the bottom surface echo of the ultrasonic signal through the bottom surface thickness, detect the signal at the abnormal position as a damage signal, and then determine the damage information in the carbon fiber material.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method for ultrasonic detection of complex curved carbon fiber materials based on a robotic arm are implemented.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps in the ultrasonic detection method for complex curved carbon fiber materials based on a robotic arm are implemented as described in any one of claims 1 to 7.

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