Robust Nonlinear Control for a Piezoelectric Actuator in a Robotic Hand Using Only Position Measurements

A robust nonlinear control based only on position measurements to compensate for the strong hysteresis nonlinearity in a piezoelectrically actuated robotic hand is proposed. Based on a high-gain observer to estimate the hysteresis response and nonlinear control law, locally exponential stable results are obtained. The observer and controller are arranged to conform to an output-feedback scheme, which is simple to implement and does not require additional computation as soon as the model parameters are identified and known. The proposed control technique is valuable for hysteresis that is modeled with the classical Bouc-Wen model. The results provide a closed-loop system that is robust under external disturbances in all the system states. Simulations show the effectiveness of the approach.