Model reference compensation for hysteresis system based on Extended State Observer

The exists of hysteresis nonlinearities in some physical system such as piezoelectric actuators can cause reduction of control accuracy and even instability of system. In this paper, a control strategy based on Extended State Observer (ESO) is proposed for systems with hysteresis characteristics to achieve accurate output tracking for the reference model which provides the desired performance. Firstly, a hysteresis nonlinear system was transformed into linear system preceded by hysteresis nonlinear disturbance in input. Secondly, the controlled object model is transformed into Equivalent Feedback Model (EFM) with reference model in forward path and internal disturbance in feedback loop. Then, ESO is designed to estimate and compensate the equivalent disturbance and control law was developed to alleviate the hysteresis effect and achieve desired tracking performance. Simulation results of a piezo-positioning mechanic system illustrate that ESO-based controller has good tracking performance.