一种改进的NURBS曲线插补算法

针对NURBS曲线曲率变化过快或出现曲率不连续点会导致插补进给速率变化过快,超出机床的加减速能力。提出一种利用NURBS曲线曲率特征的改进插补算法。该算法根据NURBS曲线曲率的变化情况将曲线分成曲率平缓段和曲率突变段,在前瞻过程中扫描出曲率突变段,获得该段的起始点、终止点及最低速率点等信息,采用梯形加减速方法对该段进行速度规划,以满足机床动态特性,实现在曲率平缓段以指令速度插补,在曲率突变段以规划速度平滑插补。仿真实验结果表明,在保证加工精度的前提下,该增强算法以较高效率实现了曲率突变段的平滑插补。

Improved algorithm of NURBS interpolation

For the large change of NURBS curve curvature or curvature discontinuous may cause fast change of speed, and beyond the machine’s acceleration and deceleration capability, an improved NURBS interpolation algorithm is proposed by using curve’s geometrical features. The curve is divided into two parts named gentle curvature segments and sudden change curvature segments. According to the sudden change curvature segment’s beginning point, ending point and the lowest speed point, trapezoidal acceleration and deceleration method is used for speed optimization to realize fast and smooth interpolation. The simulation results indicate that this improved NURBS interpolation algorithm can get a smooth feedrate profile with high efficiency and ensure the machining accuracy.