Modeling stress effects on frequencies of a MEMS ring gyroscope

We present, for the first time, an analytical model for the external stress effects on the frequencies of a vibrating ring gyroscope (VRG). The stress-induced anchor displacements cause gap changes in the electrodes and nonhomogeneous boundary conditions in the VRG’s suspension structure. Stress stiffness arising from the geometric nonlinearity in the suspension is the principal mechanism affecting VRG’s frequencies as it dominates variations of the electrostatic softening. We validate our model using external stress tests performed on a 57kHz VRG equipped with 16 symmetrically distributed, on-chip capacitive stress sensors, which provide anchor displacement measurements.