A look-ahead and adaptive speed control algorithm for high-speed CNC equipment

A novel look-ahead and adaptive speed control algorithm is proposed. The algorithm improves the efficiency of rapid linking of feedrate for high-speed machining and avoids impact caused by acceleration gust. Firstly, discrete S-curve speed control algorithm is presented according to the principle of S-curve acceleration and deceleration. Secondly, constraints of linked feedrates are derived from several limits, including the axis feedrate and feed acceleration limits, the circular arc radius error limit, and the machining segment length limit. With these constraints, the optimal linked feedrate is sought to achieve the maximum feedrate by using look-ahead method. Since the actual ending velocity of machining segment equals to the corresponding optimal linked feedrate, speed control of each segment can be executed. Finally, the proposed algorithm is implemented in a pipe cutting CNC system, and experimental results show that the proposed algorithm achieves a high-speed and smooth linking feedrate and improvements in productivity and stationarity.