A self-centering and stiffness-controlled MEMS accelerometer

Area of Science:

• Micro-Electro-Mechanical Systems (MEMS)
• Inertial Sensors
• Advanced Control Systems

Background:

• MEMS accelerometers are crucial for various applications but suffer from temperature drift and instability.
• Existing tuning methods often lack comprehensive control over critical parameters like stiffness and reference position.
• Effective compensation for environmental factors is essential for high-performance inertial sensing.

Purpose of the Study:

• To present a high-performance MEMS accelerometer with DC/AC electrostatic stiffness tuning.
• To develop a dynamical model incorporating electrostatic tuning and temperature effects.
• To implement a novel control strategy for enhanced stability and accuracy.

Main Methods:

• Development of a dynamical model for a double-sided parallel plate (DSPP) MEMS accelerometer.
• Implementation of DC/AC electrostatic stiffness tuning for effective stiffness adjustment and geometric offset calibration.
• Design of a self-centering closed loop for optimal force-to-rebalance (FTR) positioning.
• Integration of a stiffness closed-loop to prevent pull-in instability.
• Real-time temperature drift compensation using reference position and DC tuning voltage adjustments.

Main Results:

• Achieved a temperature drift coefficient (TDC) of approximately 7 μg/°C.
• Demonstrated an Allan bias instability of less than 1 μg.
• Successfully implemented a novel control approach combining self-centering, stiffness control, and temperature compensation.
• Validated the effectiveness of electrostatic tuning for accelerometer performance enhancement.

Conclusions:

• The proposed MEMS accelerometer with integrated control strategies offers superior performance and stability.
• The novel control approach effectively mitigates temperature drift and ensures reliable operation.
• This design represents a significant advancement in high-performance inertial sensing technology.