A DSP-based fuzzy robust tracking control for piezoelectric servosystems

In this paper, a DSP-based fuzzy-linear-model robust tracking control (DFRTC) is developed for the piezoelectric servosystem (PS) with dominant hysteresis. The PS is approximated by the weighted combination of N fuzzy linear pulse transfer functions. The DFRTC contains equivalent control and switching control. Based on the fuzzy model, the equivalent control is designed by the dead-beat to the switching surface for every ideal subsystem. Then the H-infinity-norm of the sensitivity function between the switching surface and the output disturbance is minimized. Although the effect of the output disturbance is attenuated, the control accuracy may not be good enough. The switching control based on the Lyapunov redesign is applied to improve the control performance. The stability of the overall system can be verified by Lyapunov stability theory. The experiments of the PS are given to confirm the usefulness of the proposed control.