Research On Interpolation Algorithm For Complex Curve Based On Forward Feed Control

Modern compute numerical control(CNC) is one of the crucial step in modern manufacture. The impirtant critrion evaluating CNC system propertis, which is always interpolation function and algorithm. Non-Uniform Rational B-Spline (NURBS) interpolation can improve the processing precision and surface smoothness, and progress production and the locus (track) function of CNC system.And it directly influences on CNC system, as well as progressing whole propertis of CAD/CAM.So, NURBS curve direct interpolation increasingly become one of the study hotspot recently.Firstly the geometry model of NURBS cueve is analyzed detailedly,. and the forward feed control of matrix expression based on NURBS cueve is established, depending on investigating and analysing adequately the study actuality for the direct interpolation of NURBS curve interiorly and oversea.In contrast with mostly arithmetic, it minishs count quantities observaly during the interpolation,and ensures the real time of arithmetic.Secondly based on analyzing conventional pulse interplation and data sampling interplation algorithm, the direct interpolation and the improving arichmetic of NURBS curve are inveatigated mainly.Aiming at its problems,for example the difficulty of controlling curve bow-high and processing safety, the improving interplation algorithm of adaption oneself that can autoregulate feeding step depending on process conditions is established.With curvature decreasing the step increases,which ensure high speed. And with curvature increasing the step decreases,which ensure mashining precision. In order to ensure the smothness of speed during interpolation, the control of speed-up and speed-down in the course of NURBS-curve interpolation are inveatigated depending on forementioned researches.Finally C++ program is used implementing the proposing interpolation algorithm,the compute simulation is carried out in the environment of VC++6.0 program and the exactness and feasibility of arithmetic are testified.At the same time,how to utilize OpenGL technology achieving the display of NURBS curve surface is investigated.This work is provide with the theoretics value for promoting the propertis of CNC system and important application value of pracitcal engineering.