Real-time correction of gain nonlinearity in electrostatic actuation for whole-angle micro-shell resonator gyroscope

Area of Science:

• MEMS gyroscope technology
• Nonlinear dynamics in micro-resonators
• Inertial sensing

Background:

• MEMS gyroscopes offer excellent Cost Size Weight, and Power (CSWaP) advantages, driving research.
• Increased vibrating amplitudes enhance signal-to-noise ratio (SNR) but introduce detrimental nonlinear effects.
• Understanding and mitigating these nonlinearities is crucial for advancing MEMS gyroscope performance.

Purpose of the Study:

• To investigate the general nonlinear mechanism, specifically actuation gain nonlinearity, in parallel-plate capacitive MEMS gyroscopes.
• To develop and validate a real-time correction method for electrostatic actuation gain nonlinearity.
• To quantify the performance improvements in a micro-shell resonator gyroscope (MSRG) after applying the correction.

Main Methods:

• Developed a theoretical model to analyze actuation gain nonlinearity and its impact on angle-dependent bias.
• Conducted experiments on a micro-shell resonator gyroscope (MSRG) to verify theoretical predictions.
• Implemented a real-time gain modification technique based on online parameter estimation of capacitive detection signals.

Main Results:

• Actuation gain nonlinearity was shown to cause control-force coupling and introduce a 4th-order angle-dependent bias.
• The proposed real-time correction method reduced the 4th-order angle-dependent bias by over 95% (from 0.003°/s to <0.0001°/s).
• Bias instability (BI) improved 3.5-fold (0.101°/h to 0.029°/h), and scale factor nonlinearity (SFN) decreased by an order of magnitude (2.02 ppm to 0.21 ppm).

Conclusions:

• Actuation gain nonlinearity is a significant factor affecting MEMS gyroscope performance, particularly angle-dependent bias.
• The developed real-time correction method effectively linearizes electrostatic actuation, enhancing gyroscope accuracy and stability.
• This approach offers a practical solution for improving the performance of whole-angle MSRGs across various operating conditions.