Vibration sensitivity analysis of MEMS vibratory ring gyroscopes

Abstract

This paper presents a detailed model for possible vibration effects on MEMS degenerate gyroscopes represented by vibratory ring gyroscopes. Ring gyroscopes are believed to be relatively vibration-insensitive because the vibration modes utilized during gyro operation are decoupled from the modes excited by environmental vibration. Our model incorporates four vibration modes needed to describe vibration-induced errors: two flexural modes (for gyro operation) and two translation modes (excited by external vibration). The four-mode dynamical model for ring gyroscopes is derived using Lagrange's equations. The model considers all elements comprising a ring gyroscope, namely the ring structure, the support-spring structures, and the electrodes that surround the ring structure. Inspection of this model demonstrates that the output of a ring gyroscope is fundamentally insensitive to vibration due to the decoupled dynamics governing ring translation versus ring flexure, however, becomes vibration-sensitive in the presence of non-proportional damping and/or capacitive nonlinearity at the sense electrodes.