| Micromachined vibratory gyroscope has been studied widely and deeply for its unique advantages and broad applications. In this thesis, the interface circuit of vibratory gyroscope is designed, simulated and tested, which features electrostatic driving and capacitance detection. The main contents in this thesis are described as follows:(1) Based on the mechanical model of gyroscope, the dynamic equations are deduced. The motion of the driving mode and the sensing mode is analyzed. The relationship between the driving signal and the gyro sensitivity are derived.(2) The whole interface circuit is studied, which is divided into two parts. One is the driving-circuit and the other is the detecting-circuit. Based on analyzing the C-V converting circuit, the detecting-circuit is designed in details. For driving-circuit, the phase locked loop and constant amplitude loop are described in details. In resonance condition, the driving signal and the driving mode displacement signal are in phase-quadrature. Using this characteristic, this paper adopts phase locked loop to adjust the frequency of the driving signal in accordance with the differ(?)nce of the natural frequency in the driving mode. The constant amplitude loop utilizes half-wave rectification circuit and DC voltage adjustment circuit to keep the driving signal constant.(3) In order to verify the scheme validity, a PCB has been made including a fork vibratory gyroscope. The experiment shows that the interface circuit can reduce the output noise, improve the gyro sensitivity and the stability of scale factor effectively.(4) Because of the noise and temperature drifts in analog components, most parts of the interface circuit are implemented in digital form. The digital hardware circuit is designed and the software is debugged.The study about the interface circuit of vibratory gyroscope and its digitization provide useful references for the progress in designing a gyroscope and drive the application of MEMS gyroscope. |
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