Adaptive tracking control solely using displacement feedback for a piezo-positioning mechanism

An adaptive displacement tracking control using only displacement feedback is proposed for a piezo-positioning mechanism. In order to develop a dynamic model to represent the overall system dynamics of the controlled piezo-positioning mechanism, a specific function is proposed. This function that describes the hysteresis of the controlled mechanism contains information on the mechanical. motion dynamics, hysteresis friction, disturbance load and parameter variations. Based on the developed model, an adaptive backstepping displacernent tracking control is proposed, in which the backstepping adaptation of the specific function and the estimation of the reconstructed state with an unknown specific function are presented. The proposed control design leads to an improved tracking performance, and robustness to the external load-disturbance, and variations in system parameters. The validity of the proposed control design is demonstrated by experimental results.