The Research On The Key Technologies Of Free Surface Reconstruction

Reverse engineering is an important component of the modern advanced manufacturing technology. It is an important means of the rapid design and agile manufacturing of products. Therefore it was widely used in motor vehicles, aircraft, household appliances, mold manufacturing. At present, both at home and abroad, reverse engineering study on the product geometry and the structure reverse associated with the function elements, That is the reconstruction of the digital prototype models. From the perspective of the geometric model reconstruction of products,Reverse engineering can be narrowly defined as the sum of the computer-aided technology, the digital measurement technology and reconstruction of the geometric model.Reverse engineering technology at home and abroad have been widely studied and the corresponding equipments and softwares have been launched. But a comprehensive, systematic solution to reverse engineering, there are still many needs to be studied and resolved. In this thesis several key technologies of free-form surface reconstruction have been studied , including:1. The thesis research on the measuring method of unknown surface through coordinate measuring machine. An automatic tracking algorithm of a surface based on the least-squares method is presented . Sampling density distribution varies with the degree of curvature of the surface.The larger Curvature,the more sampling points. Measurement data points should facilitate the follow-up surface reconstruction.2. In the data processing, Focusing on①Moving average filtering;②Local Regression Smoothing;③Data subparagraph according to the curvature distribution;④The probe radius compensation based on Delaunay Trianguation.3. The thesis research on the least-squares fitting algorithm of line,arc,and NURBS curves. The fitting process of above curves are achieved by the MATLAB software.Curves feature recognition technology based on the the goodness of fit are presented.4. The generation of extrude surface,rotating surface,Swept surface,skin surface are realized with GRIP programs. Which make the intensity of work reduce and raise the efficiency of the model.