基于三维点云的铸件飞边打磨点提取及拟合方法

Extraction and Fitting Method of Casting Flash Grinding Points Based on 3D Point Cloud

针对自动化打磨铸件中的打磨区域提取和确定打磨路径的问题,提出一种基于铸件三维点云的飞边打磨点提取及打磨路径拟合的方法。利用先临三维Ein Scan-Pro激光扫描仪获取铸件原始点云数据,结合点云边缘检测和近邻点搜索算法,获取飞边的内边缘,确定飞边打磨的基本高度位置。运用点云的单侧面投影算法,边缘检测和DBSCAN聚类算法获取铸件待打磨区域的整体边缘。为了提高打磨路径拟合效率,利用体素采样方法对整体边缘进行下采样处理,同时,将下采样点分为拟合点集和评价点集。运用三次非均匀B样条曲线拟合方法对拟合点集进行插值拟合,得到打磨路径。最后利用评价点集评价拟合效果,得出评价点集与曲线中的最近邻点的平均距离为0.174812 mm,均方根误差为0.24956,拟合后的曲线可作为铸件飞边打磨路径的参考,满足铸件边缘粗加工的要求。

Aiming at the problems of extracting the grinding area and determining the grinding path in the automatic grinding of castings,amethod of extracting the grinding points and fitting the grinding path based on the three-dimensional point cloud of the casting was proposed.Using the Shining 3D Ein Scan-Pro laser scanner to obtain the original point cloud data of the casting,combined with the point cloud edgedetection and the nearest neighbor search algorithm,the inner edge of the flash edge was obtained,and the basic height position of the flashedge grinding was determined.The single side projection algorithm of point cloud,edge detection and DBSCAN clustering algorithm were usedto obtain the overall edge of the casting area to be polished.In order to improve the fitting efficiency of the grinding path,the voxel samplingmethod was used to down-sample the overall edge,and at the same time,the down-sampling points were divided into a fitting point set and anevaluation point set.Using the cubic non-uniform B-spline curve fitting method,the fitting point set was interpolated and fitted,and thegrinding path was obtained.Finally,the evaluation point set was used to evaluate the fitting effect,and the average distance between theevaluation point set and the nearest neighbor point in the curve was 0.174812 mm,and the root mean square error was 0.24956.The fittedcurve can be used as a reference for the casting flash grinding path,to meet the requirements of rough machining of the edge of the casting.