Machining, Measurement, and Control Laboratory

1 9 9 9    J o u r n a l    P a p e r

A study on multi-axis contouring error on the transient state in NC machine tools
Jun Fujita (Toshiba Machine Co., Ltd.)
Sadaji Hayama (Toshiba Machine Co., Ltd.)
Minoru Hamamura (Toshiba Machine Co., Ltd.)
Kazuhiro Shiba (Toshiba Machine Co., Ltd.)
Atsushi Matsubara (Kyoto University)
Yoshiaki Kakino (Kyoto University)

This project focuses on the analysis and compensation of dynamic motion errors in two- dimensional synchronous motions of an NC machine tool. First, by analytical calculations as well as numerical simulations, it is shown that the difference of the velocity feedback loop bandwidths and natural frequencies between each of X- and Y-axis feed drive systems causes transient motion errors, when linearly interpolated motions inclined from the X-axis by 45 degrees are considered. Compensation methods based on dynamic matching of each axis and an acceleration feedforward control scheme are proposed to reduce such transient motion errors. Contouring error profiles simulated by using the proposed model are compared to measured profiles for several different combinations of servo controller gains. The results validate the effectiveness of proposed tuning methods for parameters in a velocity feedback controller and an acceleration feedforward controller.

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