Modeling, testing and control of a parametrically-excited mirror with duty-cycled excitation

Electrostatically-actuated MEMS mirrors are used in a variety of applications ranging from mass sensing, gyroscopes, resonators, and displays to, more recently, endoscopic imaging, as for premalignant cancer detection. The aim of this work is to analytically and experimentally characterize the dynamics and stability of a 1D torsional micro-mirror undergoing parametric resonance for use in biomedical imaging. Analysis focuses on the effects of duty cycle variations on the stability and amplitude of micro-mirror motion. Additionally, the paper explores how proportional control can be implemented with duty cycle as the input to ensure that the desired scanning angles for imaging can be obtained. The paper outlines fundamental and simplifying assumptions made for each analysis, discusses the validity of associated models, and compares analytical outcomes to respective experimental results. Analytical models agree reasonably with experimental models in stability predictions at modest voltages and can provide more limited predictions of amplitudes given sufficient prior experimentation to estimate damping coefficients.