| 摘要: |
| 优化电容检测接口并采用力反馈控制方案能够在不影响表头敏感结构的情况下，通过改变环路参数提高加速度计的信噪比，改善加速度计性能。基于一款阵列式差分电容的加速度计敏感结构，在等效电容模型的基础上，通过电容检测接口电路的搭建与输出信号的频谱分析，验证了单载波电容检测电路具有更出色的输出信噪比。后级采用STM32H743VIT6微处理器实现调幅信号的数字解调，经PI控制算法调节后作为反馈电压施加于可动极板，实现了加速度计的数字闭环控制。实测结果显示，闭环状态下加速度计的速度随机游走（VRW）为57 μg/Hz1/2，与开环状态相当，而零偏稳定性则从开环状态的184 μg改善至58 μg，验证了单载波调制型电容检测接口和力反馈控制技术对提升加速度计静态性能的具体效果。 |
| 关键词: 电容式微机电加速度计 单载波调制 力反馈控制 阵列式结构 |
| DOI： |
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| Interface noise detection and digital closed-loop control based on capacitive MEMS accelerometer |
| GUO Zihan,HU Zhongxu,WU Xinyi,LIU Fei,LIU Weipeng,SHEN Yanchao |
| (Beijing Institute of Automatic Control Equipment, Beijing 100074, China;The First Military Representative Office of the Army Equipment Department in Beijing Area, Beijing 100070, China;Shanghai Electro-Mechanical Enineering Institute, Shanghai 201109, China) |
| Abstract: |
| Optimizing detection interface and adopting force feedback control scheme can improve the signal-to-noise ratio(SNR) and the performance of MEMS accelerometer by changing the circuit parameters without affecting the sensitive structure of the MEMS sensor. Based on an array differential capacitance sensitive structure, the capacitance detection interface circuit is constructed and the output signal spectrum is analyzed on the basis of the equivalent capacitance model. It is proved that the single carrier capacitance detection has better output SNR. The STM32H743VIT6 processor is used for digital demodulation of the amplitude-modulated signals. It is applied to the movable pad as a feedback voltage, after the demodulation value is adjusted by PI control algorithm, and the digital closed-loop control of the accelerometer is realized. Experimental results has demonstrated that the velocity random walk(VRW) of the closed-loop accelerometer is 57 μg/Hz1/2, which is equivalent to that of the open-loop state. However, the bias stability of the accelerometer is improve from 184 μg in the open-loop state to 58 μg, which verifies the effect of the single-carrier modulated capacitance detection interface circuit and the force feedback control technology on improving the static performance of the accelerometer. |
| Key words: Capacitive MEMS accelerometer Single carrier modulation Force feedback control Array structure |
