Study On High-speed And High-precision NURBS Interpolation Algorithm And Its Interpolator Implementation

NURBS curve interpolation technology has been widely applied and also been the highlight of interpolation algorithm research.This dissertation mainly researches interpolation algorithm about feedrate scheduling in adjacent sensitive points region,proposes the feedrate scheduling and acceleration/deceleration schemes aiming at different sensitive points region in order to improve the kinematics performance and guarantee the machining precision.Firstly,mathematic foundation of NURBS curve is elaborated with DeBoor algorithm to calculate coordinates of curve points and curve derivatives,and the second-order Taylor's expansion method is adopted to calculate parameters of NURBS curve.Then,the classification and searching method of sensitive points are presented.Commencing with the feedrate scheduling of adjacent sensitive points region without intersection,different feedrate scheduling schemes with S-shaped acceleration profile curve are adopted within different sensitive region.And feedrate modification method is proposed at the breakpoints,which can further smooth the feedrate profile at the neighboring of these sensitive points.Moreover,with discussion of intersection types of feedrate scheduling between adjacent sensitive points,the criterion of different intersection types is proposed,and the corresponding feedrate scheduling scheme is presented for each different intersection types.In addition,searching method for the intermediate feedrate is proposed for the specific intersection type.Furthermore,considering that the intersection influence of adjacent sensitive region in feedrate scheduling,so the algorithm for the whole NURBS curve is proposed to determinate corresponding feedrate scheduling scheme and acceleration/deceleration.Finally,utilizing the DSP chip with high-speed calculating capacity,NURBS curve interpolator is implemented by hardware.Later than that,NURBS curve interpolation algorithm proposed in this dissertation is simulated by software and is experimented in hardware,which verifies the superiority of NURBS interpolation algorithm of this dissertation compared with the general algorithm.