Modified ADRC with composite nonlinear feedback for a piezoelectric-actuator driven nano-manipulating stage

In this paper, a modified active disturbance rejection control (ADRC) structure composed of a linear extended state observer (LESO) and a composite nonlinear feedback controller (CNFC) is developed to improve the transient performance of the micro/nano-manipulating systems. In particular, the controller adopts the LESO to estimate the “total disturbance” and then compensates it through the CNFC. The linear feedback part is designed with a small damping ratio such that the closed-loop system yields a fast response. The nonlinear feedback controller composed of the specific structure of the augmented system is exploited to eliminate the overshoot of the closed-loop system as the system output approaches the target reference. The proposed control architecture is deployed on a customize-designed nano-stage driven by a piezoelectric (PZT) actuator, where real time experiments demonstrate good transient performance and stead-state accuracy in high precision positioning.