Abstract: In order to improve contour controlling accuracy of Computer Numerical Control（CNC） system，the problem that control software of the system can directly output spline must be solved.Iterative relationship between parameters of two adjacent interpolation points on a Non-Uniform Rational B Spline（NURBS） curve is obtained based on Taylor formula.To B spline basis functions and their arbitrary order derivatives which need to be frequently calculated during interpolating a NURBS curve，a uniform calculating method of block matrix multiplying continuously is presented.Numerical calculation method is used to solve some relative problems such as curve’s length and so on during interpolating.The example demonstrated here indicates that the proposed method can be applied to actual CNC system.

摘要： 为提高计算机数字控制（CNC）系统的轮廓控制精度，需解决系统控制软件样条直接输出的问题。基于Taylor公式得到了非均匀有理B样条（NURBS）曲线上两个相邻插补点参数间的递推关系。对于NURBS曲线插补过程中需要频繁计算的B样条基函数及其任意阶导数提出了一种分块矩阵连乘积形式的统一计算方法。应用数值计算方法解决了插补过程中曲线长度等的相关计算问题。实例运算表明所提出的方法可以应用到实际CNC系统中。