Digital Closed-Loop Control Method for MEMS Quad-Mass Gyroscope Based on Synchronous Integrator Demodulation

Traditional demodulation algorithms for microelectromechanical systems (MEMS) gyroscopes exhibit poor noise resistance and demodulation misalignment. This paper proposes a digital closed-loop control method for MEMS Quad-Mass Gyroscopes (QMG) based on a synchronous integrator demodulation (SID) algorithm, achieving demodulation output of drive/detection signals. Utilizing the SID algorithm, a digital closed-loop measurement and control system for MEMS gyroscopes is established. In the drive mode closed-loop, phase-locked loop technology and automatic gain control technology ensure constant amplitude and frequency resonance of the gyroscope. For the sensing mode, the quadrature stiffness correction method is employed to correct quadrature errors, suppressing the impact of these errors on bias output. Electrostatic feedback is used to suppress the Coriolis force signal, allowing the gyroscope to operate in a force balance mode. Experimental results show that with the multiplication demodulation (MD) method, the bias instability of the MEMS QMG is 0.407°/h and the angle random walk is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.137^{\circ}/\sqrt{\mathrm{h}}$</tex>. With the SID, the bias instability reduces to 0.192°/h and the angle random walk to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.039^{\circ}/\sqrt{\mathrm{h}}$</tex>, representing a 2.1 times reduction in bias instability and a 3.5 times reduction in angle random walk. These results verify the effectiveness of the proposed method.