MATHEMATICAL MODEL OF RR-TYPE MICROMECHANICAL GYRO CAPACITIVE COMB-TYPE SENSORS WITH ACCOUNT FOR VIBRATIONS

Abstract

Subject of Research.The reasons for subharmonic resonances in RR-type micromechanical gyro output under linear vibrations are investigated. In ideal case, this type of gyro should be insensitive to this kind of impact due to primary and secondary angular oscillations. However, experimental results reveal significant increase in output signal under external vibrations in 20 Hz - 2 kHz bandwidth, though the device natural frequencies are above 3 kHz. This effect is caused by characteristicsnonlinearity of plate-type and comb-type capacitive sensors. Method. Mathematical model of the capacitive comb-type sensors is clarified. Electromechanical interactions in the sensors under external vibrations are described. Simulink modeling of specified mathematical model is carried out. External vibration modeling is doneby “oscillating frequency” method with constant accelerationamplitude in 20 Hz - 2 kHz bandwidth. Main Results.We have received good agreement of modeling and experimental results in the form of occurrence of subharmonic resonances under linear vibrations in three orthogonal directions. Obtained effects are explained by proposed mathematical models. The main reason for subharmonic resonances in RR-type micromechanical gyro output is that combs of stator and combs of proof mass jump out of mesh. Practical Relevance. The provided investigation gives the possibility to determine algorithmic and construction compensation methods of studied interactions for enhancing vibration resistance of RR-type micromechanical gyro.

Keywords

• micromechanical gyro
• vibration
• subharmonic resonance