Interactive Errors Analysis and Scale Factor Nonlinearity Reduction Methods for Lissajous Frequency Modulated MEMS...

Area of Science:

• * MEMS Gyroscopes
• * Control Systems Engineering
• * Signal Processing

Background:

• * Lissajous frequency modulated (LFM) mode enhances stability in MEMS gyroscopes.
• * Scale factor (SF) nonlinearity limits full-scale accuracy in LFM MEMS gyroscopes.
• * Interaction effects of coupling, phase delays, and amplitude mismatch contribute to SF nonlinearity.

Purpose of the Study:

• * To investigate the primary factors causing SF nonlinearity in LFM MEMS gyroscopes.
• * To develop and validate error compensation methods for reducing SF nonlinearity.
• * To enhance the accuracy of MEMS gyroscopes for precise measurements.

Main Methods:

• * Analyzed interaction effects among stiffness coupling, system phase delay, readout demodulation phase shift, and velocity amplitude mismatch.
• * Implemented frequency difference control and demodulation phase matching.
• * Suppressed stiffness coupling using instantaneous frequency difference observation and quadrature voltage.
• * Compensated system phase error by observing amplitude control force and tuning Phase-Locked Loops (PLLs) reference.

Main Results:

• * Identified remaining stiffness coupling and residual system phase error as key drivers of SF nonlinearity.
• * Achieved a 97% reduction in SF nonlinearity within the ±500°/s measurement range via simulations.
• * Demonstrated that a sufficiently large frequency split effectively constrains SF nonlinearity.

Conclusions:

• * Stiffness coupling and system phase error are the main contributors to SF nonlinearity in LFM MEMS gyroscopes.
• * Proposed error compensation strategies effectively mitigate SF nonlinearity, significantly improving gyroscope accuracy.
• * Maintaining adequate frequency split is crucial for constraining SF nonlinearity in MEMS gyroscopes.