硅微陀螺仪接口位移噪声对检测性能的影响

研究了基于调制解调的硅微陀螺仪检测信号提取原理,推导了开环检测传递函数。根据调制解调的频谱转移特性,提出了有效位移噪声是高斯窄带噪声。推导了开环检测时位移噪声的等效角速度公式,分析表明,要提高噪声性能可以减小噪声功率密度、带宽和增加陀螺仪机械灵敏度。同时还推导了闭环检测时位移噪声的等效角速度公式。通过比较开环检测和闭环检测情况下由接口位移噪声导致的噪声等效角速度表明:闭环检测并不能减少由接口位移噪声导致的平均噪声等效角速度。据此设计实际电路,试验结果表明在100Hz频段内,闭环检测噪声谱密度基本等于开环检测噪声谱密度,验证了理论的正确性。

Influence of Position Measurement Noise on Performance of Silicon Micromachined Gyroscope

The signal detecting means based on modulation and demodulation of Silicon Micromachined Gyroscope is research.The expression of transfer function is induced in open-loop detection.According to frequency spectrum transfer characteristic of modulation and demodulation,we think the position measurement noise is Gaussian narrowband noise.The equivalent rotational rate formula of the position measurement noise is deduced in open-loop detecting.The analysis indicateis that it can improve noise performance by increasing the mechanical sensitivity of the SMG or reducing power density and bandwidth of the position measurement noise.At the same time,the equivalent rotational rate formula of the position measurement noise is deduced in closed-loop detecting.By calculating and comparing the equivalent rotational rate of the position measurement noise both in the opened-loop detecting and in the closed-loop detecting,we find that the closed-loop detecting does not reduce the equivalent rotational rate of the position measurement noise.According to opened-loop detecting theory and closed-loop detecting theory,an experiment circuit is designed.The experiment results indicate,in 100 Hz frequency spectrum,output signal power density in closed-loop detecting basically equals the output signal power density in opened-loop detecting,which validates correct of the theory mentioned above.