Structural design and experimental characterization of torsional micromachined gyroscopes with non-resonant drive mode

This paper reports a novel gimbal-type torsional micromachined gyroscope with a non-resonant actuation scheme. The design concept is based on employing a 2 degrees-of-freedom (2-DOF) drive-mode oscillator comprising a sensing plate suspended inside two gimbals. By utilizing dynamic amplification of torsional oscillations in the drive mode instead of resonance, large oscillation amplitudes of the sensing element are achieved with small actuation amplitudes, providing improved linearity and stability despite parallel-plate actuation. The device operates at resonance in the sense direction for improved sensitivity, while the drive direction amplitude is inherently constant within the same frequency band. Thus, the necessity to match drive and sense resonance modes is eliminated, leading to improved robustness against structural and thermal parameter fluctuations. In the paper, the structure, operation principle and a MEMS implementation of the design concept are presented. Detailed analysis of the mechanics and dynamics of the torsional system is covered, and the preliminary experimental results verifying the basic operational principles of the design concept are reported. (Some figures in this article are in colour only in the electronic version)