Effects of electrostatic nonlinearity on the rate measuring performance of ring based Coriolis Vibrating Gyroscopes (CVGs)

Electrostatic nonlinearities are the dominant source of nonlinearity in ring-based capacitive Coriolis Vibrating Gyroscopes (CVGs) and have potential to parametrically amplify the sense response of the ring resonator and enhance measurement sensitivity. This paper investigates the effects of electrostatic nonlinearities on the rate-measuring performance of a ring-based capacitive CVG. A nonlinear mathematical model is used to describe the dynamics of the drive and sense modes for a ring resonator including the presence of structural imperfection. For a conventional 8 electrode configuration it is found that the direct and mode-coupled nonlinear stiffnesses for the mode pair are generally unequal, even for perfectly axisymmetric ring structures. These differences are found to affect the scale factor, bias and quadrature error of the gyroscope, and act to split the amplitude-dependent resonant frequencies but with the presence of self-induced nonlinear parametric pumping. The interaction of these effects with small structural imperfections is demonstrated and it is shown that under certain circumstances nonlinearity is able to negate the imperfection effects. [Display omitted] •Using 8 electrodes split the Duffing and cubic-order elastic coupling stiffnesses.•The split enhances growth of quadrature error at high quality factors.•Nonlinearities can enhance scale factor in the presence of imperfections.•Nonlinearities can eliminate zero-rate errors.