Abstract:

Since NURBS has its own particularities,a NURBS curve feedrate model was constructed based on de Boor algorithm. This model consisted two parts-feedrate adaptive control and pre-interpolation acceleration/deceleration(acc/dec).The chord error, shear acceleration and normal acceleration of whole interpolation period were monitored and controlled based on de Boor algorithm. In order to calculate the distance of deceleration zone of the NURBS curve, a concept of NURBS reverse interpolation was introduced,which was illustrated by linear acc/dec.This model feasibility has already been proved in real CNC system.

Key words: NURBS curve, de Boor algorithm, linear acc/dec, NURBS reverse interpolation, chord error

摘要：

以NURBS曲线de Boor递推插补算法为基础，针对NURBS曲线速度处理的特殊性，建立了一种NURBS曲线自适应速度控制模型,
该模型分为速度自适应控制和插补前加减速处理两部分。以de Boor算法为基础对整个插补周期的弓高误差以及切向和法向加速度进行实时监控，分析了误差产生的原因并进行了相应的速度控制；以插补前直线加减速为例引入NURBS反向插补的概念，解决了NURBS曲线减速区长度计算问题。实验结果表明，该模型满足实际的NURBS曲线插补的需要。

关键词: NURBS曲线, de Boor算法, 直线加减速, NURBS反向插补, 弓高误差