振动式微机械陀螺驱动控制电路研究

Study on the Circuit of Driving Loop Control for Micromachined Vibratory Gyroscope

本文分析了微机械陀螺检测灵敏度和驱动信号频率和幅度的关系,在此基础上提出了一种振动式微机械陀螺驱动控制环路方案并给出了相应的电路实现方法.它利用陀螺谐振时驱动信号和驱动模态位移信号具有900相位差这一特性,采用锁相方式完成驱动轴的稳频控制,恒幅控制环节则采用半波整流电路及后续的直流电压调整电路实现,从而完成了对驱动轴的锁相和恒幅双环路控制,保证了陀螺驱动轴的谐振和振幅恒定,有效的提高了陀螺的灵敏度和标度因子的稳定性.最后针对音叉电容式微机械陀螺进行的开闭环对比实验证明,添加控制环路的检测电路零偏稳定性提高了10倍左右.

Based on the mechanical model of the MEMS vibratory gyroscope, the relationships between the driving signal and the gyro sensitivity are derived. It shows that in order to obtain a high sensitivity and low drift, the gyroscope must be working in resonance condition, and the amplitude of driving signal must be constant. For these considerations, a driving circuit with phase locked loop and constant amplitude loop is described. 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 difference 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. The experiment shows that, with the phase locked loop and constant amplitude control, the driving circuit reduces the output noise, improves the gyro sensitivity and the stability of scale factor.