基于模态匹配和正交抑制的微机电陀螺闭环控制技术研究

Closed-loop control of a MEMS gyroscope with mode match and quadrature trimming

模态匹配和力反馈控制可以在不牺牲检测带宽的情况下,利用机械谐振放大特性有效提高微机电陀螺信噪比、改善陀螺性能。结合一款高Q值对称式四质量敏感结构的陀螺表头,在陀螺动力学平均模型基础上,通过对检测模态同相分量和正交分量的控制,实现陀螺的闭环检测控制。基于静电负刚度原理,通过改变陀螺敏感结构梳齿与质量块之间的电压,构建实时正交抑制系统和精确模态匹配环节,推导出陀螺的静电刚度矩阵,完成了对正交耦合信号的实时抑制和驱动、检测模态的精确模态匹配并且实现对两环节的解耦控制。实测结果显示,陀螺频差由24 Hz缩小到0.05 Hz以内,全温条件下,陀螺的正交耦合量由3(°)/s抑制到0.01(°)/s,陀螺全温零偏稳定性由初始的11.48(°)/h改善到1.95(°)/h,验证了实时正交抑制和模态匹配等技术对提升陀螺性能的具体效果。

Mode matching and force rebalance control can effectively improve the SNR(signal-noise ratio)and performance of MEMS(micro-electro-mechanical system)gyroscope by using mechanical resonance amplification without a bandwidth trade-off.A measurement and control circuit is built based on a high-Q quad mass MEMS gyroscope sensor.On the basis of the average model of the gyro dynamic equation,the closed-loop detection control of the gyro is achieved by controlling the in-phase and quadrature components of the detection mode.Based on the principle of electrostatic negative stiffness,a real-time quadrature trimming system and an exact mode matching are constructed by changing the voltage between comb and mass block of the gyro sensitive structure,and the electrostatic stiffness matrix of the gyro is deduced.The real-time quadrature trimming of quadrature trimming signals and the exact mode matching of detection mode are completed,and the decoupling control of them is realized.Experimental results have demonstrated that the frequency difference of the gyroscope is reduced from 24 Hz to less than 0.05 Hz,and the quadrature coupling of the gyroscope is suppressed from 3(°)/s to 0.01(°)/s at full temperature.The bias stability of the gyroscope over a full temperature range is improved from 11.48(°)/h to 1.95(°)/h,which verifies the effect of mode matching and real time quadrature trimming on improving the performance of the gyroscope.