Adaptive Piecewise NURBS Curve Interpolator Algorithm for Entireness Process S-curve ACC/DEC Control 

An adaptive piecewise NURBS curve interpolation algorithm based on 7-segment S-curve ACC/DEC control along the entire curve was present to meet the requirements of the modern CNC high-speed and high-precision machining.The algorithm adaptively divided a NURBS curve into small segments according to the information of the

curve geometry, and calculated the value of the parameters of the curve segments.This algorithm adaptively adjusted the ACC/DEC time of the velocity curve,which was corresponding with the 17 kind of types of the S-curve ACC/DEC conditions.At a fixed interpolation cycle, compared the proposed algorithm with alone adaptive algorithm and 5-segment S-curve ACC/DEC control method, the simulation and analysis results show that the interpolation precision of the proposed algorithm is higher than that of the alone adaptive interpolation method, and is approximate to the 5- segment S-curve ACC/DEC control method under the limitations of acceleration and jerk and the maximum chord height error being less than 0.5μm. Furthermore, the average feed rate along the full curve of the proposed algorithm is increased by 21.7%,compared with that of the 5-segment S-curve ACC/DEC control method,and which can reach 594mm/s.

为满足现代数控加工的高速度、高精度要求,提出基于7段式S曲线加减速全程规划的NURBS曲线自适应分段插补算法。该算法根据NURBS曲线几何形状将其自适应分段,并计算曲线段各项参数值、对应S曲线加减速规划（速度规划为17种类型）中加减速类型和自适应调整速度曲线加减速时间。在固定插补周期下,与单独自适应算法、5段式S曲线加减速控制方法的仿真结果相比,在满足加速度与加加速度限制条件,且最大弦高误差不超过0.5μm时,该算法插补精度高于单独自适应算法,与5段式S曲线加减速控制方法近似,且其全程平均进给速度比5段式S曲线加减速控制方法平均进给速度提高21.7%,达到594mm/s。

自适应, 分段插补, S曲线加减速控制, NURBS曲线