Modal harmonie simulation of decoupled resonators for developing MEMS tuning fork gyroeope with low acceleration sensitivity

This paper presents analysis of the acceleration sensitivity (output) in decoupled resonators and a proposal of a new method to suppress acceleration output by controlling frequency decoupling of coupled resonators for developing MEMS tuning fork gyroscope (TFG) with low acceleration sensitivity. We identified that unbalancing of two sense resonators in TFG caused by fabrication error converts external acceleration into anti-phase vibration. This anti-phase vibration appeared as the rate output, which is called acceleration output in gyroscope. In order to reduce the acceleration output, decoupling between in-phase and anti-phase modal frequency is crucial, since coupled resonators may cause large anti-phase vibration from acceleration. To confirm the acceleration output model, we designed two types of decoupling methods of artificially unbalanced resonators. Through modal harmonic analysis, the anti-phase vibration reduced by one-tenth by increasing decoupling ratio from 0.09 to 0.29, irrespective to resonator designs.