Robust servo control using PI-Luenberger observers with application to nonlinear piezo-electrically actuated systems

This paper deals with servo control of SISO nonlinear systems driven by piezoelectric actuators operating in highly uncertain conditions. A proportional-integral (PI) Luenberger observer-based controller is systematically designed to achieve accurate tracking performance, enforce desired closed loop dynamics, as well as robust disturbance rejection in the presence of nonlinearities and model uncertainties. The controller presented offers many advantages including simplicity, ease-of-tuning and implementation in wide variety of applications involving piezoelectric-based actuators. Closed loop experimental results show tracking performance robustness is indeed realized in the presence of the plant nonlinearities and the actuator hysteresis.