Macro-modelling of a double-gimballed electrostatic torsional micromirror

Abstract

This paper presents the development of a reduced-order macro-model for the double-gimballed electrostatic torsional micromirror using the hierarchical circuit-based approach. The proposed macro-model permits extremely fast simulation while providing nearly FEM accuracy. The macro-model is coded in MAST analog hardware description language (AHDL), and the simulations are implemented in the SABER™ simulator. Both the static and dynamic behaviour of the double-gimballed electrostatic torsional micromirror have been investigated. The dc and frequency analysis results obtained by the proposed macro-model are in good agreement with CoventorWare™ finite element analysis results. Based on the macro-model we developed, system-level simulation of a closed-loop controlled double-gimballed torsional micromirror is also performed. Decentralized PID controllers are proposed for the control of the micromirror. A sequential-loop-closing method is used for tuning the multiple control loops during the simulation. After tuning, the closed-loop controlled double-gimballed torsional micromirror demonstrates an improved transient performance and satisfactory disturbance rejection ability.