插补前S加减速在CNC前瞻中的应用

Application of pre-interpolation S-shape acceleration/deceleration in CNC look-ahead interpolation algorithm

计算机数字控制系统(CNC)中的速度前瞻处理可以在不影响插补轨迹精度的前提下极大地提高插补效率.针对前瞻算法中速度处理这一核心问题,分直线转接和圆弧转接2种情况分别建立了插补几何元素转接矢量夹角模型,并给出了一种基于插补前S型加减速的CNC速度前瞻算法.该算法根据设定的最大前瞻段数以及实际插补轨迹的几何特性,能够自适应确定轨迹的转接速度近似最优解,从而实现路径段之间进给速度的高速衔接.S型加减速由于在加速阶段和减速阶段均引入了加速度衰减,使得整个插补过程具有了高度的柔性.因此结合前瞻算法和S型加减速算法在高速加工时速度处理的优势,提出并实现了一种基于插补前S型加减速的CNC前瞻算法.该算法已经在工程实际中得到了验证.

Aiming at improving the interpolation efficiency without lowering the path accuracy, the velocity look-ahead control in CNC（computerized numerical control） was introduced. Firstly, the interpolation geometry elements linking vector angle model, which was separated into line-connect condition and circle-connect condition, was proposed. The CNC velocity look-ahead control algorithm was presented. This novel algorithm can find the approximate optimal velocity adaptatively based on the maximum number of look-ahead segments and the geometric properties of the interpolation path, then the high connected velocities between segments can be achieved. Because introducing the acceleration attenuation in acceleration zone and deceleration zone, the S-shape acc/dec（acceleration/deceleration） can improve the flexibility of interpolation. By combining the advantages of the look-ahead control algorithm and the S-shape acc/dec in high velocity condition, a novel S-shape acc/dec CNC look-ahead interpolation algorithm was introduced and realized. This algorithm feasibility has already been proved in real CNC system.