In-run bias self-calibration for low-cost MEMS vibratory gyroscopes

We present a method for improving bias instability and Rate Random Walk (RRW) in low-cost MEMS vibratory gyroscopes by periodically reversing polarity of the resonator drive force, yielding a 5 times reduction of RRW noise. The feasibility of the approach was experimentally evaluated using an in-production Analog Devices ADXRS800, a fully integrated MEMS gyroscope with a quadruple mass architecture. The proposed method is to use periods of alternating co-phase and anti-phase drive clock to drive-mode oscillation periods, and sampling the gyroscope sense-mode output during the equal times of co-phase anti-phase drive of the resonator, thereby canceling the drive alignment bias error term. The proposed self-calibration method allows for long and short term stability improvement in low-cost and high performance MEMS vibratory gyroscopes.