测量数据和区域精度加权的模型配准方法

Registration Method Based on Composite Weighting Parameters of Measured Data and Regional Accuracy

模型配准广泛应用于零件加工定位及精度检测。使用光学扫描技术获得的三维点云数据疏密程度与曲面的曲率有关,每个测量点所代表的测量面积不同,因此在模型配准时每个测量点应具有不同作用。另外,由于设计要求和制造工艺等的影响,零件表面各区域的精度存在差异,故配准时要考虑这种区域精度差异以保证高精度区域的配准效果。提出一种基于测量数据疏密和区域精度的加权模型配准算法,通过复合权因子控制不同数据在配准中的作用,得到更加符合工程实况的配准结果。仿真和实测数据实验结果证明,对精度存在差异和曲率变化较大的曲面所提配准算法比最近点迭代算法更加实用和有效。

Model registration is widely used in localization and inspection of parts. It remains a challenging problem in some situations. The density of the measured points of the parts depended on the surface curvature in 3D optical scan measurement technology. The local surface in small curvature was to enable more accurate representation with comparatively sparse measured points. Thus the area authorized by each point was different. So each point should be endowed with different status in registration progress. In addition, for a complex part with multiple free form surfaces, different precision requirements were often specified to different regional surfaces in design,and manufacturing process might make the precision difference in regions. Without consideration of the difference,the existing registration methods were prone to obtain the result which balanced the surface error. In the case,the error of the surface with high precision became larger than the physical truth,and the error of low precision regions turned out to be just the opposite. Based on the two aspects,a registration method based on composite weighting parameters of measured point area and regional geometric accuracy was proposed.Composite weighting parameters were constituted by estimating regional precision iteratively and calculating the area of the Voronoi diagram of each measured points. They controlled the influence of different data on the registration. As a result,the registration conformed more to the real engineering.Both theoretical and experimental results verified the efficiency and availability.