一种谐振式微加速度计表芯非线性动力学分析及实验

Analysis and experiment on nonlinear dynamics of resonant micro-accelerometer

在研制基于静电刚度谐振式微加速度计过程中,发现增大激励电压可以提高输出信噪比,但响应的振动幅度将不稳定,同时谐振频率也将会出现漂移。针对上述问题,建立了静电驱动微机械谐振系统等效行为模型,非线性动力学理论分析结果与实验现象一致,总结出需要从加速度计结构参数优化和减小激励电压两个方面来减小频率漂移和提高分辨率。将结构优化准则应用到制造的微加速度计上,实验结果表明:在5 V敏感电压下,闭环条件下单梁加速度计灵敏度为58 Hz/g,分辨率为3.5 mg。

In the process of developing the resonant micro-accelerometer based on electrostatic stiffness, it is found that： increasing the driving voltage can improve the output SNR, but the vibration magnitude of the response would be unstable, and resonant frequency would have drift errors. To solve this problem, a non-linear dynamic model for the resonant accelerometer was built to characterize the phenomena, the theory analysis result using this model is in agreement with the experiment phenomena. Theory analysis and experiments results show that we can reduce the frequency drift and improve the resolution by decreasing the driving voltage and optimize the geometry of the resonator. With the above conclusions, the accelerometer was driven and tested by a self-sustained oscillation loop, and the test results show that when the sensing voltage is 5V, the sensitivity is 58 Hz/g and resolution is 3.5mg for a single vibratory beam.