Vibration-Induced Errors in MEMS Tuning Fork Gyroscopes with Imbalance

Area of Science:

• Micro-Electro-Mechanical Systems (MEMS)
• Inertial Sensors
• Vibration Analysis

Background:

• Ideal MEMS tuning fork gyroscopes (TFGs) are assumed immune to vibrations, but real-world devices have inevitable imbalances.
• Fabrication imperfections like stiffness, mass, and damping imbalances affect TFG performance.
• Understanding vibration-induced errors is crucial for reliable TFG applications.

Purpose of the Study:

• To investigate vibration-induced errors in non-ideal MEMS TFGs.
• To analyze the impact of different fabrication imbalances on TFG vibration sensitivity.
• To compare the vibration performance of various TFG designs.

Main Methods:

• Simulation of four TFG designs with varying imbalance ratios.
• Focus on the coupling types between the two gyros in both drive and sense directions.
• Analysis of vibration sensitivities across different TFG configurations.

Main Results:

• Type CC TFGs (coupled in both drive and sense directions) exhibit the highest insensitivity to vibrations near operating frequencies.
• Sense-axis vibrations at in-phase resonant frequencies cause significant errors in sense-coupled TFGs, linked to sense capacitance nonlinearity.
• Increased stiffness coupling reduces sensitivity to operating frequency vibrations but amplifies sensitivity to in-phase frequency vibrations.

Conclusions:

• Non-ideal TFGs are susceptible to vibration-induced errors, contrary to the ideal model.
• TFG design, particularly the coupling configuration, significantly impacts vibration resilience.
• Careful design and consideration of fabrication imperfections are necessary to mitigate vibration errors in MEMS TFGs.