Piezoelectric Disk Gyroscope Fabricated With Single-Crystal Lithium Niobate

Abstract

A piezoelectric disk gyroscope fabricated with a single-crystal lithium niobate (LN) wafer has been developed for inertial navigation systems for localization during automated driving. LN has a high electromechanical coupling coefficient and a resonator made of a low-cost single-crystal wafer shows a high quality factor, which is suitable for high-performance vibratory gyroscopes. In this study, its crystallographic anisotropies in both in elastic and piezoelectric properties were considered to realize mode matching in the two-wine-glass-mode vibration of a disk resonator. We chose a 155°-Y-cut LN wafer because we found that its elastic compliance is uniform in any in-plane direction. Its anisotropic piezoelectric properties were considered to optimize the electrode design to oscillate the wine-glass modes efficiently. A 25.8-mm-diameter, 330- μm-thick disk resonator with 16 electrodes on each side was designed and fabricated by photolithography and grinding. The as-fabricated LN disk resonator was successfully oscillated in two wine-glass modes with a small frequency split of 0.7% at 95 kHz resonant frequency. Gyroscope operation was successful and the scale factor was 0.35 μV/°/s without any preamplifier.