Quadruple Mass Gyroscope Angle Random Walk Reduction Through Linearized Transduction

Abstract

A quadruple mass Coriolis vibratory gyroscope operating in the mode-matched condition has been redesigned with the singular focus of minimizing nonlinear transduction mechanisms, thereby allowing for angle random walk (ARW) noise reduction when operating at amplitudes higher than $2~\mu \text{m}$ . This is achieved through the following steps: (i) redesigning the Coriolis mass folded flexures and shuttle springs, (ii) linearizing the antiphase coupler spring rate while maintaining parasitic modal separation, (iii) replacing parallel plate transducers with linear combs, (iv) implementing dedicated force-balanced electrostatic frequency tuners, and (v) microTorr vacuum packaging enabling operation at the thermoelastic dissipation limit of silicon. Additionally, cross-axis stiffness is reduced through folded-flexure moment balancing to further reduce ARW. By the balancing of positive and negative Duffing frequency contributions, net frequency nonlinearity was further reduced to −20 ppm. The gyroscope presented in this study has achieved an ARW of 0.0005 deg/ $\surd $ hr, with an uncompensated bias instability of 0.08 deg/hr. These advancements hold promise for enhancing the performance of precision vibratory gyroscopes for navigation and North-finding applications. [2023-0144]