Ellipsoidal design of robust tracking controller for large-stroke piezoelectric actuators

This paper presents a new robust controller for position tracking of long-stroke piezoelectric actuators (PEAs). The nonlinear hysteresis model associated with PEA is approximated as a linear part with a bounded disturbance, which is treated as an external disturbance to be rejected by the proposed controller. The invariant ellipsoids method is employed where the technique of linear matrix inequalities is the main tool. In the proposed approach, the effect of disturbance on the dynamic performance can be drastically reduced by minimizing the size of the invariant ellipsoids of the dynamical system. The proposed approach has been implemented and tested using a commercial long-stroke piezoelectric actuator. Experimental results show that the proposed controller has a better tracking performance when compared to model-free or adaptive-fuzzy controllers in motion tracking.