Roberto Carminati

Parametric Resonance in Electrostatically Actuated Micromirrors

We consider an electrostatically actuated torsional micromirror, a key element of recent optical microdevices. The mechanical response is analyzed with specific emphasis on its nonlinear features. We show that the mirror motion is an example of parametric resonance, activated when the drive frequency is twice the natural frequency of the system. The numerical model, solved with a continuation approach, is validated with very good accuracy through an extensive experimental campaign.

Smart System Case Studies

This chapter presents two case studies showing how the proposed approach applies to smart system design and optimization. The former is the virtual prototyping platform built for a laser pico-projector actuator, where MEMS, analog and digital components are simulated with the aim of optimizing the resulting image quality by means of firmware tuning. The latter, in the context of wearable equipment for inertial body motion reconstruction, deals with the modeling of an inertial sensor node, supporting system accuracy evaluation and sensor fusion enhancement. Finally, the Open-Source Test Case (OSTC) is described, showing a complete modeling and simulation flow on a publicly available design.

Mode Coupling and Parametric Resonance in Electrostatically Actuated Micromirrors

The main torsional mode of electrostatically actuated micromirrors is known to be dominated by parametric resonance when the actuation is performed via in-plane comb fingers. Here, we show that, for specific geometrical features of the mirror, parametric resonance simultaneously activates a spurious yaw mode. Due to the large torsional rotations, the two modes are nonlinearly coupled, inducing mutual stiffness variations and an unexpected temperature dependence of the main mode. After presenting an experimental evidence of the coupling, we develop and discuss a numerical model capable of capturing the key phenomena and of providing guidelines for a robust design.