Sensor Design Migration: The Case of a VRG

Vibrating ring gyroscopes (VRG) have been shown to achieve a high scale-factor with low non-linearity while some structural modification can help increase their shock resistance in space applications. With some tuning, their quadrature error can be nearly eliminated, thus, minimizing device sensitivity to external factors while keeping a good alignment between the drive and sense-mode frequencies. VRG design is optimized for high scale-factor, low non-linearity, and high shock-resistance while satisfying process related constraints. When the device wafer is processed independent of the capping wafers, the process imposes topology constraints on the device trenches and forces anchors and other stator features to be on the outside of the device. In this paper, we have shown how a VRG that has been designed with a radially outwards topology, having its anchor in the center as the innermost component, can be reconfigured into a VRG with a radially inwards topology with its anchors at the rim as the outermost component. This design transformation can be construed as a VRG design migration from a three-wafer process to a single-wafer process. The process-driven reconfiguration comes at the cost of a lower scale-factor but with no impact on the operating range of the original design. The paper further proposes the use of directional masses to achieve better inertial modal control of the VRG. The resulting radially inwards VRG has been fabricated in the standard SOIMUMPS process, and preliminary experimental results have shown the functionality of the device under atmospheric pressure.