Frequency modulation based angular rate sensor

We report, for the first time, a quasi-digital angular rate sensor based on mechanical frequency modulation (FM) of the input rotation rate. The new approach relies on tracking of the resonant frequencies of two ultra-high Q-factor mechanical modes of vibration in a MEMS vibratory gyroscope to produce a frequency based measurement of the input angular rate. Rate table characterization of the new FM angular rate sensor with quality factors of 1 million revealed a linear dynamic range of 2000 deg/s limited by the setup, with a fundamental performance limit in excess of 72,000 deg/s. Temperature characterization of the FM rate sensor exhibited less than 0.2 % variation of the angular rate response between 25 °C and 70 °C environments, enabled by the self-calibrating differential frequency detection.