一种面向点云制造自由曲面的CMM自适应采样方法

Adaptive sampling method for CMM oriented to point cloud machined free-form surfaces

通过分析点云制造过程,提出了一种面向点云制造自由曲面的CMM自适应采样方法。首先,提取点云边界并选择初始采样点,进而依据中间曲面与原始点云之间的偏差不断自适应地增加采样点,直至满足采样精度要求。并提出了相应的点云边界提取方法以及点云与自由曲面偏差的计算方法。最后,将所提方法与具有代表性的两种采样方法:基于高斯曲率的自适应采样和等参数采样进行了对比,并分别以三种方法得到的采样点在三坐标测量机上进行测量,通过测量结果及测量时间的对比验证了所提出的自适应采样方法能够在提高采样效率的同时保持较高的采样精度,且该方法不依赖于曲面的CAD模型,因此能够应用于点云制造自由曲面的测量及检测。

An adaptive sampling method for coordinate measurement machine （CMM） oriented to point cloud ma- chined free-form surfaces is proposed by analyzing the point cloud machining process. Firstly, choose some original sampling points by extracting the edge of the point cloud, and then iteratively add the sam- piing points according to the biggest deviation between the original point cloud and the substitute surface until the sampling precision is reached. Meanwhile, the edge extraction method of the point cloud and the computation method of the deviation between the point cloud and the free- form surface are proposed. Finally, the proposed method is compared with the two typical sampling strategies, which are Gaussian curvature-based method and the iso-parametric method. Furthermore, the sampled points of these three methods are separately used on a CMM to measure a free-form surface, the comparative re- suits show that the proposed method can improve the measurement efficiency and accuracy. By the way, the proposed sampling method is independent of the CAD model of the surface to be measured, thus it can be used for measuring or inspecting the point cloud machined free-form surfaces.