MEMS陀螺仪结构模型及系统仿真

Structure model and system simulation of MEMS gyroscope

为了减小MEMS陀螺仪的正交误差,进一步提高陀螺精度,在Simulink环境中对陀螺结构和测控系统进行了建模和仿真。首先在理想状态的陀螺结构模型基础上建立了包含机械热噪声、模态间耦合等非理想因素的结构模型,并给出了陀螺结构的相关设计参数。其次在陀螺结构模型上以自激振荡和AGC控制技术为基础设计了驱动回路,该回路可在短时间内将驱动幅度稳定在10μm,且驱动频率为4048 Hz(驱动模态的谐振频率)。然后分析了模态间耦合信号的作用方式并建立了正交校正和检测闭环力反馈回路,仿真结果显示,在全闭环状态下检测模态所受耦合力的幅度比未校正状态下降了5个数量级,等效输入角速度也从205(°)/s下降到了6.58(°)/h。最后对陀螺模型进行了整体测试,得到其标度因数和阈值分别为21.76 mV/(°)/s和0.002(°)/s。

The model of micro-electro-mechanical system （MEMS） gyroscope structure and monitor circuit is investigated and simulated in Simulink in order to decrease the quadrature error and enhance the gyroscope＇s precision. Firstly, the model is established based on the ideal gyroscope＇s model and some imperfect elements, such as the mechanical thermal noise, coupling signal between two modes, and then the parameters are proposed. After that, the close loop drive system is designed based on self-resonant and AGC technology, the amplitude and frequency of drive frame are stabilized at 10 μm and 4048 Hz （drive mode＇s resonant frequency） respectively within one second. Then, the quadrature error correction and sense force feedback rebalance loops are built. The simulation result indicates that, after correction, the coupling force＇s amplitude is decreased by 105 times, and its equivalent input angular rate is reduced from 205 （°）/s to 6.58 （°）/h. Finally, the overall test is made which shows that the scale factor and the threshold value are 21.76 mV/（°）/s and 0.002 （°）/s.