基于低频调制激励的硅微陀螺仪自动模态匹配技术

Automatic mode-matching technology for silicon MEMS gyroscope based on low-frequency modulation signal

根据二阶质量-弹簧-阻尼系统的幅频特性和相频特性关于谐振频率对称的特点,提出了一种低频振荡激励的实时模态匹配技术,根据检测模态的输出响应来判别驱动模态和检测模态的匹配程度。首先简要介绍了带频率调谐功能的双质量线振动硅微陀螺仪,该陀螺利用负刚度效应来调节检测模态的谐振频率;然后通过理论推导以及系统仿真验证了基于低频调制激励的自动模态匹配技术的可行性和有效性;最后设计了一种基于现场可编程逻辑阵列(FPGA)的数字控制电路,并且对同一测试陀螺进行了模态匹配和模态不匹配下的性能对比。试验结果表明,相比模态不匹配条件下,陀螺零偏稳定性从5.89(°)/h提高到1.26(°)/h,角度随机游走从0.36(°)/√h提高到0.079(°)/√h,性能分别提高了4.7倍和4.6倍。

In view that the 2nd-order mass-spring-damper system has approximate symmetry resonance frequency characteristics, an automatic mode-matching technology driven by low-frequency modulation signal is presented. At first, the dual-mass silicon MEMS gyroscope with the function of frequency tuning is introduced, which uses the gyroscope＇s negative stiffness effect to adjust the resonance frequency of the sense mode. Then, the automatic mode-matching technology of low frequency modulation is verified by theoretical derivation and system simulation. Finally, the digital control circuit based on field programmable logic array（FPGA） is designed, and the performances of the proposed gyroscope are tested under the mode-matching condition and mode-mismatching one, respectively. Experiment results demonstrate that the gyroscope＇s performances under mode-matching condition are significantly improved compared with those under mode-mismatching condition, in which the bias instability is improved from 5.89（°）/h to 1.26（°）/h, and the angle random walk is improved from 0.36（°）/√h to 0.079（°）/√h, showing that the performances are improved by about 4.7 times and 4.6 times, respectively.