A Resonant Controller Design of Piezo-electrically Driven Micro-lens Actuator

A novel controller and its experimental implication for fast auto-focusing capability of a piezo-electrically driven micro-lens actuator is presented in this paper. Negative imaginary (NI) theory is used to design the feedback controller for the micro-lens actuator. A resonant controller is also a part of overall feedback control. The design is based on the identified model of the cantilever and it is implemented on a micro-lens actuator. The result shows that the application of the designed controller damps the first resonance mode of the actuator by 17 dB. The closed-loop system also demonstrated a reduction of settling time from 119 ms to 8 ms which indicates the significant improvement in auto-focusing as well as optical zooming of the micro-lens.