硅微静电加速度计的支承刚度特性

Suspension stiffness of micromachined electrostatically suspended accelerometers

静电加速度计通过降低带宽和量程在空间微重力环境下可以实现极高的分辨率。设计了一种采用玻璃-硅-玻璃"三明治"结构、平行六面体状检验质量、体硅加工工艺的三轴硅微静电加速度计,推导并讨论了静电支承回路的典型刚度特性与控制参数之间的关系式。采用基于DSP的数字控制器,实现了敏感质量的六自由度稳定支承,在大气环境下测试了静电支承回路的主要性能。分析与测试结果表明,在支承系统频带内,支承刚度特性与控制器参数及气膜阻尼系数密切相关;同时,改变预载电压可以在较大范围内在线调整加速度计的量程和支承刚度等指标。

Electrostatically suspended accelerometers can offer extremely high resolution in micro-gravity space measurement with significantly reduced operating bandwidth and measurement range. In this paper, a tri-axis micromachined electrostatically suspended accelerometer（MESA） was designed with a free parallelepiped proof mass, and realized in a glass-silicon-glass sandwich structure by bulk silicon micromachining. The relationships between dynamic stiffness characteristics and control parameters in a typical suspension loop were derived and discussed. A DSP-based digital control scheme was realized to achieve stable levitation of the proof mass electrostatically in six degrees of freedom. The analytical and experimental results of the accelerometer operated in the atmospheric environment show that the suspension stiffness is mostly dominated by controller parameters and air damping within the closed-loop suspension bandwidth. It is also shown that the allowable input range and suspension stiffness of such accelerometers can be varied over a wide range by changing the preload voltage online.