Closed-Loop Control and Output Stability Analysis of a Micromechanical Resonant Accelerometer

Area of Science:

• Mechanical Engineering
• Electrical Engineering
• Physics

Background:

• Micromechanical resonant accelerometers are vital for inertial navigation and sensing applications.
• Understanding electrostatic stiffness is key to improving accelerometer performance.

Purpose of the Study:

• To analyze the dynamic equation of a micromechanical resonant accelerometer based on electrostatic stiffness.
• To identify parameters influencing accelerometer sensitivity and stability.
• To evaluate the accelerometer's performance using Allan variance analysis.

Main Methods:

• Dynamic equation analysis of electrostatic stiffness.
• Establishment of the dynamic equation for closed-loop self-excited drive.
• Application of the average period method for stability analysis.
• Allan variance analysis for performance evaluation.

Main Results:

• Sensitivity is enhanced by increasing proof mass and capacitor plate area, decreasing fold beam stiffness and initial capacitor distance, and increasing detection voltage.
• A sensitivity of 321 Hz/g was achieved at 2V detection voltage.
• Frequency deviation of 0.04 Hz and amplitude deviation of 0.06 mV were observed within 30 min at room temperature.
• Resolution improved to 56ug with a temperature error of ±0.01 °C.
• The fully overlapping Allan variance analysis method (FOAV) offers the highest accuracy but requires significant data and time.

Conclusions:

• The study provides a comprehensive analysis of micromechanical resonant accelerometer dynamics and sensitivity.
• Design parameters for enhanced sensitivity and stability have been identified.
• The accelerometer demonstrates high precision and stability, with potential for further improvement.