Yu Sheng, Sun Jiangkun, Zhang Yongmeng, Xi Xiang, Lu Kun, Shi Yan, Xiao Dingbang, Wu Xuezhong
National University of Defense Technology, Changsha, 410073, China.
Microsyst Nanoeng. 2024 Nov 5;10(1):164. doi: 10.1038/s41378-024-00818-x.
MEMS gyroscopes are well known for their outstanding advantages in Cost Size Weight and Power (CSWaP), which have inspired great research attention in recent years. A higher signal-to-noise ratio (SNR) for MEMS gyroscopes operating at larger vibrating amplitudes provides improved measuring resolution and ARW performance. However, the increment of amplitude causes strong nonlinear effects of MEMS gyroscopes due to their micron size, which has negative influences on the performance. This paper carries out detailed research on a general nonlinear mechanism on the sensors using parallel-plate capacitive transducers, which is called the gain nonlinearity in electrostatic actuation. The theoretical model established in this paper demonstrates the actuation gain nonlinearity causes the control-force coupling and brings extra angle-dependent bias with the 4 component for the whole-angle gyroscopes, which are verified by the experiments carried out on a micro-shell resonator gyroscope (MSRG). Furthermore, a real-time correction method is proposed to restore a linear response of the electrostatic actuation, which is realized by the gain modification with an online parameter estimation based on the harmonic-component relationship of capacitive detection. This real-time correction method could reduce the 4 component of the angle-dependent bias by over 95% from 0.003°/s to less than 0.0001°/s even under different temperatures. After the correction of actuation gain nonlinearity, the bias instability (BI) of whole-angle MSRG is improved by about 3.5 times from 0.101°/h to 0.029°/h and the scale factor nonlinearity (SFN) is reduced by almost one order of magnitude from 2.02 ppm to 0.21 ppm.
微机电系统（MEMS）陀螺仪因其在成本、尺寸、重量和功耗（CSWaP）方面的突出优势而闻名，近年来受到了广泛的研究关注。对于在较大振动幅度下工作的MEMS陀螺仪，更高的信噪比（SNR）可提供更高的测量分辨率和角随机游走（ARW）性能。然而，由于其微米级尺寸，幅度的增加会导致MEMS陀螺仪产生强烈的非线性效应，这对性能有负面影响。本文对使用平行板电容式传感器的传感器中的一般非线性机制进行了详细研究，这种机制在静电驱动中被称为增益非线性。本文建立的理论模型表明，驱动增益非线性会导致控制力耦合，并给全角度陀螺仪带来与角度相关的额外四分量偏置，这在微壳谐振器陀螺仪（MSRG）上进行的实验中得到了验证。此外，还提出了一种实时校正方法来恢复静电驱动的线性响应，该方法通过基于电容检测的谐波分量关系进行在线参数估计来修改增益来实现。这种实时校正方法即使在不同温度下也能将与角度相关的偏置的四分量从0.003°/s降低95%以上，降至小于0.0001°/s。在校正驱动增益非线性之后，全角度MSRG的偏置不稳定性（BI）从0.101°/h提高了约3.5倍，至0.029°/h，标度因数非线性（SFN）从2.02 ppm降低了近一个数量级，至0.21 ppm。
