Digital closed-loop driver design of micromechanical gyroscopes based on coordinated rotation digital computer algorithm

Abstract

A novel digital closed-loop driver is presented for a micromechanical vibratory gyroscope in this paper. Coordinated rotation digital computer algorithm is applied to generate the sine and cosine signals for driving and demodulation processing. Meanwhile, automatic gain control and phase-locked loop are adopted to maintain a constant velocity of the drive mode and guarantee the gyroscope working in the resonant mode. All the control methods are implemented in FPGA device. Experimental results demonstrate that the stability of the amplitude of the drive velocity is about 18ppm, which verifies the effectiveness and accuracy of the digital closed loop for the drive mode. The scale factor, nonlinearity and bias instability of the gyroscope with closed loop controlled sense mode are measured to be 18.5mV/deg/s, 0.088% and 19.4deg/h, respectively.