Demonstration of a wide dynamic range angular rate sensor based on frequency modulation

This paper reports a detailed characterization of a new rate gyroscope based on the mechanical frequency modulation (FM) of the input rotation. The FM approach tracks the resonant frequency split between two high-Q mechanical modes of vibration in a MEMS Coriolis Vibratory Gyroscope (CVG) to produce a frequency-based measurement of the input angular rate. The FM approach was implemented using a silicon micromachined Quadruple Mass Gyroscope (QMG) transducer. Structural characterization of a vacuum packaged QMG showed symmetrical Q-factors on the order of 1 million over a wide temperature range from -40 °C to +100 °C. High speed rate table testing of the FM angular rate sensor demonstrated inherent linearity up to 18,000 deg/s (50 revolutions per second, limited by the setup) with a dynamic range exceeding 125 dB. Interchangeable operation of the QMG transducer in conventional AM and proposed FM regimes provides a dynamic range above 155 dB (from sub-deg/hr to 18,000 deg/s).