Research On Potimal Reconstruction Method Of Sectional Profile Based On Features And Constraints

With the rapid development of industrial manufacturing technology and computer technology, and the new theory and technology is introduced, the new product development speed and technical requirements are also getting higher and higher. Reverse engineering can rapid digestion and absorption of advanced technology, occupies an important position in the process of product innovation and development. The reverse engineering modeling technology based on the features has been proved to be a kind of reverse modeling method which is the most can reflect product design intentions, but in the reverse modeling method based on section contour feature, to reverse the high precision industrial parts, reconstruction quality of section contour curve is still inadequate. Based on the maximum restore of the initial design intent and reconstruct of high quality section contour curve as the goal. Mainly launches the research from the aspects of section data preliminary segmentation, segmentation points accurate extraction of section contour curve,construction section contour optimization reconstruction model based on the G1 continuity constraints, and nonlinear constraint simplification etc.In the reverse engineering modeling technology based on the features, section data acquisition and data preprocessing is the precondition of reconstruction section contour curve. Introduced the use of three coordinate measuring machine for section data of traditional measurement method, further illustrates the measure before the data measurement, and to follow certain rules of measurement. Studied as a main method for section data of point cloud slicing, based on detailed point cloud slicing algorithm, studied the method of slicing direction on simple quadric surface and free surface.Studied the section data preliminary segmentation method by using the discrete curvature estimation and interactive experience, Given the section feature type identification method in detail based on curve fitting. In the cross section data preprocessing phase,the segmentationaccuracy has an important influence on the subsequent reconstruction of sectional contour between adjacent different feature data. Straight line, arc and B-spline curve is the main feature of the cross section outline curve, use the function of smoothing filter can soften the boundary features, segmentation point interval extraction algorithm is proposed when the boundary constraint is G1 continuous, for precise segmentation points provide search range for the next step. In the case of arc features and freedom adjacent, proposed arc features linearization method, simplified solution model of segmentation point interval and the segmentation point.Cross section feature curve fitting expression and the G1 continuous constraint expression between curve is studied, two kinds of segmentation point accurate extraction algorithm is proposed: With B-spline curve approximation error expectations for judgment conditions, within the range using dichotomy iterative spline first control vertices to search the accurate segmentation point; According to the angle information between the tangent direction of spline curve initial fitting on the boundary and line direction, setting up the appropriate threshold value to judge the segmentation point location. Make a comparative analysis to these two kinds of methods from the efficiency and accuracy.Combined with the example of section contour reconstruction, respectively using simulated data and actual measurement data, By using this method and the existing methods are analyzed on the segmentation point extraction accuracy and the cross section contour curve reconstruction quality, verified the feasibility and applicability of this method.