Optically read Coriolis vibratory gyroscope based on a silicon tuning fork

Abstract

In this work, we describe the design, fabrication, and characterization of purely mechanical miniature resonating structures that exhibit gyroscopic performance comparable to that of more complex microelectromechanical systems. Compared to previous implementations of Coriolis vibratory gyroscopes, the present approach has the key advantage of using excitation and probing that do not require any on-chip electronics or electrical contacts near the resonating structure. More specifically, our design relies on differential optical readout, each channel of which is similar to the “optical lever” readout used in atomic force microscopy. The piezoelectrically actuated stage provides highly efficient excitation of millimeter-scale tuning fork structures that were fabricated using widely available high-throughput wafer-level silicon processing. In our experiments, reproducible responses to rotational rates as low as 1.8 × 103° h−1 were demonstrated using a benchtop prototype without any additional processing of the raw signal. The noise-equivalent rate, ΩNER, derived from the Allan deviation plot, was found to be <0.5° h−1 for a time of 103 s. Despite the relatively low Q factors (<104) of the tuning fork structures operating under ambient pressure and temperature conditions, the measured performance was not limited by thermomechanical noise. In fact, the performance demonstrated in this proof-of-principle study is approximately four orders of magnitude away from the fundamental limit.

Three-Dimensional Performance Evaluation of Hemispherical Coriolis Vibratory Gyroscopes

“…Piezoelectric quartz, used in these types of gyroscopes, showed high efficiency and quality at atmospheric pressure [ 12 ]. In addition to this, the Japanese company Murata introduced two low-cost designs in the 1990s [ 13 ]. In one of the designs, a steel-beam pattern with a triangular cross-section is used, excited and sensed by piezoelectric elements connected to the beam surfaces.…”

Development and evaluation of haltere-mimicking gyroscope for three-axis angular velocity sensing using a haltere-mimicking structure pair

“…Although they succeeded in measuring the angular velocity under atmospheric pressure, the sensor could only measure one-axis angular velocity. Lavrik and Datskos [25] also reported a haltere-inspired gyroscope that measures the Coriolis force using laser reflection. They fabricated a Y-shaped tuning fork haltere-mimicking structure and vibrated it by a PZT stage, and the reflection of the laser was utilized to measure the Coriolis force.…”

A Real-Time Circuit Phase Delay Correction System for MEMS Vibratory Gyroscopes

“…Vibratory gyroscopes work through Coriolis coupling between two orthogonal modes where one mode is forced to oscillate along the drive axis while the other operates as an accelerometer sensing the angular rate-induced Coriolis acceleration along the sense axis [ 8 , 9 ]. Limited by manufacturing imperfections and immature packaging techniques, in-phase and quadrature error, caused by damping and stiffness coupling, are inevitable for vibratory gyroscopes [ 10 ].…”