Distributed-mass micromachined gyroscopes for enhanced mode-decoupling

A novel micromachined z-axis gyroscope with multidirectional drive-mode is presented. The design concept aims to relax mode-matching requirement, eliminate effects of directional residual stresses, and completely decouple the drive and sense modes. The proposed approach is based on denning multiple drive-mode oscillators, distributed symmetrically around the center of a supporting frame. Quadrature error and zero-rate-output are minimized, since the instability and drift is suppressed, due to the enhanced decoupling of multidirectional linear drive-mode and the torsional sense-mode. By designing each drive-mode oscillator with incrementally spaced resonance frequencies, a constant total Coriolis torque is achieved over a wide range of driving frequencies, leading to relaxed mode-matching requirements; and thus, robustness and reduced sensitivity to structural and thermal parameter fluctuations are achieved. Bulk-micromachined prototypes have been fabricated in a one-mask SOI-based process, and experimentally characterized.