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| Extraction Method of Gap and Flush of Three-Dimensional Seam Point Clouds Based on SVM |
| ZHANG Bo 1 , LI Shuanggao 1 , HAO Long 1 , ZHU Kui 2 |
| (1. College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China; 2. Shenzhen JT Automation Equipment Co., Ltd., Shenzhen 518216, China) |
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Abstract Gap and flush generated among aircraft assembly should satisfy specific requirements, which should be precisely extracted in order to ensure the quality of assembly. Because of seam’s uneven size and noise of the data, gap and flush are difficult to extract accurately. Therefore, this paper proposes a method to extract gap and flush of threedimensional point cloud of seam based on SVM (Support Vector Machine). Firstly, mathematical model is established according to distribution characteristics of point cloud, in order to identify the feature points that need to be extracted. Secondly, measuring position points are planned and discreted according to the boundary of the digital model. Take the measured position points as the geometric center, and subpoint cloud is extracted based on PCA (Principal Component Analysis) and bounding box. Thirdly, point cloud is segmented by hyperplane which is adjusted. Then, boundary points, edge points and critical points are extracted by triangler point cloud. Finally, gap and flush are extracted according to mathematical models. The accuracy and stability of the method were verified through designed experiments. Experiments show that gap measurement mean error is less than 0.03mm as well as the flush measurement mean error is less than 0.02mm.
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2020, 
