Characterization of Scale Factor Nonlinearities in Coriolis Vibratory Gyroscopes

In this paper, we studied the mechanisms which contribute to Scale Factor (SF) nonlinearity in Coriolis Vibratory Gyroscopes (CVG) operating in the open-loop angular rate mode. Analytical equations were derived to quantify the effects of electro-mechanical nonlinearities, modal coupling, and nonlinear capacitive sensing on SF. Experimental results with a Dual Foucault Pendulum (DFP) gyroscope are presented and compared to simulated data of the predictive model. In our experiments, we demonstrated that by minimizing the electro-mechanical nonlinearities, the SF error is reduced by 27.7% at the angular rate of 1 Hz. We concluded that modal coupling is the major source of SF nonlinearity. We also concluded that nonlinearity in the capacitive sensing has the lowest contribution to SF nonlinearity, at angular rates up to 1 Hz. Finally, we discussed conditions under which a linear SF can be achieved.