Design and Implementation of Robust Resonant Controller for Piezoelectrically Driven Micro-Lens Actuator

MEMS based piezoelectrically driven micro-lens actuator experiences resonance frequency shift with changing actuation voltage and exhibits low level of damping. In this paper, we present the design and experimental implementation of a resonant controller, robust against the variation in dynamics, to enhance the damping at the first resonance frequency. The controller is designed using an identified model of the micro-lens actuator from experimental frequency response data at a fixed actuating voltage. The closed-loop stability is guaranteed using the mixed negative-imaginary and small-gain approach. The experimental results demonstrate a damping of 21dB of the first resonance mode. The designed controller achieved the similar level of damping for the shift in resonance frequency due to the change in the actuation voltage. The settling time, due to a step change, of the piezoelectric micro-lens actuator is reduced to 7ms from 120ms. Such quick settling time is necessary for the fast auto-focusing functionality of the piezoelectrically driven micro-lens actuator in a miniaturized camera module. [2022-0137]