Design and experiment of micro machined vibratory gyroscope

A novel MEMS vibratory gyroscope was fabricated by our research group, and its structure, packaging, signal detection and performance measurement were described. The dual-mass MEMS vibratory gyroscope was designed by a structure-decoupled method and prepared by the Deep Dry Silicon On Glass (DDSOG). To improve the mechanical sensitivity, reliability and stability, the gyroscope was packaged by vacuum technology and the common mode disturbance caused by axial acceleration was also eliminated. A self-resonance drive circuit with Automatic Gain Control (AGC) was employed in the drive closed loop to keep the stable amplitude and frequency of the drive-mode. The open loop detect circuit was adopted to simplify the whole control system. In order to reduce the temperature impact on the bias of gyroscope, the gyroscope's outputs within a certain temperature range were studied, and the relationship model between gyroscope outputs and temperature was established. On the basis of the model, a proper temperature real-time compensation system using a platinum resistor was designed to reduce the power comsumption, meanwhile to minimize the volume of the system. The experiment results show that the gyroscope has a quality factor above 100 000, the operating range of ±500(°)/s with the scale factor of 21.453 mV·(°)-1·s-1 and nonlinearity and asymmetry errors of 36.905×10-6 and 184.125×10-6 respectively. Moreover, at room temperature the bias of the gyroscope is 7.7143(°)/h over a 100 Hz bandwidth, the whole system volume is 31 mm×31 mm×12 mm and the power consumption is 288 mW. The proposed vibratory gyroscope has a promising prospect for the inertial navigation system with a medium accuracy due to its high performance, small volume and low power consumption.