硅微机械陀螺仪频率调谐控制系统设计

Mode-matching control system design of silicon MEMS gyroscope

硅微机械陀螺结构的驱动和检测模态谐振频率差(Δf)是决定其结构机械灵敏度的主要因素,当Δf≈0时,陀螺结构处于频率调谐状态,此时陀螺的机械灵敏度达到最大峰值且噪声和分辨率等指标可得到有效提高。提出了一种基于正交信号和驱动位移相位差的鉴相控制方法,以判断陀螺结构是否处于频率调谐状态,并通过调节检测模态刚度达到频率调谐目的。首先,介绍了陀螺结构检测模态谐振频率调节的原理,并结合结构参数量化分析了频率调节范围。其次,分析了鉴相控制方法,并在其基础上设计了频率调谐控制系统,建立了整机系统模型,并对其进行了稳定性分析。最后,结合整机模型进行了仿真,采用所提出的方法可实现(Δf)的快速、稳定、自主调节,系统的标度因数指标调谐前后分别为13.1 m V/(°/s)和220.6 m V/(°/s),大大提高了结构的机械灵敏度,验证了设计方案。

The resonance frequency difference（Δf） between drive and sense modes of MEMS gyroscope is one of the main factors that affect the mechanical sensitivity of gyro structure. Gyro performance（such as the signal-noise ratio, resolution, etc.） could be improved obviously ifΔf≈0 when the mechanical sensitivity achieves the peak. A phase-demodulation control method based on the phase difference between quadrature error signal and drive-mode displacement signal is proposed to judge and makeΔf≈0 automatically by adjusting sense mode stiffness. First, the working principle of the sense-mode adjusting method is introduced, and the adjusting range is calculated based on the structure model parameters. Then, based on the analysis of the phase demodulation control method, the mode-matching control system and the gyro system model are established, and the system stability is investigated. Finally, the gyro model is simulated, which show that the Δf can be adjusted rapidly, stably and automatically, and the gyro scale factors are 13.1 m V/（°/s） and 220.6 m V/（°/s） respectively before and after mode-matching. The simulation results prove that the mechanical sensitivity can be enhanced obviously by the proposed method, which can improve the performance of the MEMS gyroscope.