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 de ning multiple drive-mode oscillators, distributed symmetrically around the center of a supporting frame. Quadrature error and zero-rateoutput are minimized, since the instability and drift is suppressed, due to the enhanced decoupling of multidirectional linear drive-mode and the torsional sensemode. 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 uctuations are achieved. Bulk-micromachined prototypes have been fabricated in a one-mask SOI-based process, and experimentally characterized.