Research On Composite Surface Reverse Based On Bounding Box And Tracking Method

Surface reconstruction and surface joining are important factors in determining the precision of parts with composite surface. How to store the feature information of reconstructed surface fully after the surface reconstruction is an important part to improve the reverse accuracy in the reverse process of composite surface. The composite surface is divided into a number of single surface. After measuring and reconstructing each surface, there is a gap between surface and surface. Surfaces are extended according to the characteristic of the surface and surface intersection is conducted so as to carry out surface splicing. Surface measurement ? single surface reconstruction and surface joining are combined into reverse system.According to the law of point cloud obtained by adaptive measurement, non uniform B spline surface reconstruction is carried out by using node insertion method. The reconstructed curve and surface can only be stored in the form of the point currently which can result in a decline in the accuracy of reverse at the time that they are used in the third software. Oriented bounding box has the characteristics of closely surrounding objects. A new storage method of curve and surface is proposed based on oriented bounding box. The characteristic information of the reconstructed curve and surface is stored fully in the reverse system which realize the exchange of the reverse system and the existing software and improve the overall accuracy of the reverse of composite surface. B spline surface is reconstructed of the same point cloud with the same order in the reverse system and the existing software. The error between two surfaces is below 3 microns. The reconstruction efficiency is more than 80% faster than the existing software. Experimental results show that the saved surface information is more complete by using the proposed method.Because there has gap between surfaces and existing problems of the rigid connection of surfaces. Surfaces are extended naturally and surface intersection is conducted so as to make surfaces connected based on the reconstruction of multiple free surfaces. In view of the problem of slow speed of existing surface intersection, the tracking step is connected with the radius of curvature of the intersection. The improved tracking method is proposed based on the adaptive step which make the intersection conform to the surface features with high precision. In order to verify the effectiveness of the improved tracking method, the intersection test between different types of surfaces is carried out, and the accuracy of the intersecting line is above ?m level. The intersection of surfaces is carried out with fixed step and adaptive step. The improved tracking method has less computation. Surfaces are connected naturally in the acquisition of original point cloud of surface and surface intersection. The realization of surface intersection, creating curves and creating surface make the reverse system more perfect.