Research On Point Cloud CurveParametric Modeling Based On Identifying Feature And Constraint

As an important component of advanced manufacturing technology, reverse engineering gradually developed into an important technical means of product innov-ation and new product development from the initial prototype support replication technology. Corresponding to this trend, Reverse Engineering CAD model recon-struction of the entity is no longer a traditional model, but more innovative design capabilities, supporting for product lifecycle feature model. In the context of reverse engineering technology for feature modeling, this paper start the study to focus the understanding of the product design intent and the measurement intent, to rebuild the parametric feature model supporting for product innovation, to focus the key technologies in reverse engineering CAD modeling, such as feature recognition, constraint recognition, global optimization, parametric modeling and so on.Unorganized point cloud curve parametric modeling is very valuable both for improving the accuracy and efficiency of reconstruction and innovative design and for enriching computer graphics research. This major work done mainly in the following areas.Firstly, both the nature and the mathematical expression of the common curve characteristics and the fitting techniques of Curves by the numbers was researched. The basic meaning of point cloud feature recognition and a new feature recognition criteria was introduced. Basic characteristics of point cloud data can be identified successfully by this method. Rebulided parameters was keeped consistent with the original design parameters as much as possible.Secondly, in this paper, the expression of various constraints between common curveis was introduced. On this basis, a constraint recognition criteria was established in this paper, which can identify the constraints between the various geometry characteristics.Thirdly, rebuilding constraints of the cross section, each curve which point cloud data can be fitted to can have an overall constraint approximation to construct the shape of cross section in the conditions of meeting the constraint between paragraphs. A general the global optimization model was given to solve the problems of an overall constraint approximation in this article. The fmincon function of MATLAB Optimization Toolbox was used of solving optimization calculation. That can get effective results. The results of global optimization from approximation error and constraint error was analysed.Fourthly, in this paper, parameter design method based on the curve was researched. The parameters expression of Bezier curves and the approach to satisfy the constraint relations were given. Equidistant offset of the free curve has been researched in this paper.Finally, on the basis of summarizing the work, the content and direction of the further research were given.