Abstract: The feed motion stability of pulse driving systems is directly affected by characters of driving pulse sequences generated by CNC interpolators. The motion stability and control strategies are investigated by theoretical analysis, modeling simulation and experimental verification. Based on the mathematical model of interpolator output, the motion stability is discussed in both time-domain and frequency-domain. For traditional interpolation mode, an approach of improving motion stability is given according to the inter-restricted relation among machining accuracy, efficiency and motion stability. Furthermore, breaking through the traditional control mode, a new interpolating control strategy —an adaptive separated-axis interpolator with random period—is proposed to achieve high motion quality by varying interpolation period and synchronization of multi-axes. The results of simulations and machining experiments show the proposed strategies are effective. The efforts described provide new ways to improve the motion stability theoretically and practically.

Key words: Interpolation period, Motion control, Numerical control system, Pulse driving system