Research On Improving Performance Of MEMS Ring Gyroscope Based On Parametric Excitation

MEMS(Micro-Electro-Mechanical System)resonant gyroscope is a kind of sensor for measuring angular velocity.The gyroscopes have the features of low cost,low power,small size and can be mass produced.No matter in consumer electronics,automotive electronics and other civil fields,such as unmanned combat system,guided ammunition and other defense military fields,which has a very wide range of applications.However,on the one hand,due to the drawbacks of manufacturing process and material process,primary mode and sense mode of gyroscope is not matched very well,which will affect the energy transfer between primary mode and sense mode and make the response of sense mode become small,which will limit sensitivity.On the other hand,due to the parasitic capacitance,electrical feed-through between the drive and sense electrodes will corrupt the sense signal and affect zero drift stability,finally limits the improvements of gyroscopes and applications of gyroscopes.Besides,the asymmetry of the structure of the gyroscope also leads to the generation of the error signal,thus affecting the precision of the gyroscope.To solved above problems,firstly,by modeling a mass-spring-damping system,the electrostatic negative spring effect of the static electric power is discussed detailed,which is also called soften effect.Secondly,by theoretical derivation,system modeling and Simulink simulation,analysis of these errors above and propose solutions.Coherent demodulation,structural decoupling and correction are applied to gyroscope for the error signal caused by the asymmetry of the structure.Taking MEMS ring gyroscope as research carrier,the motion equation including parametric excitation method is derived and parametric excitation is applied to the drive mode of the resonant gyroscope when facing electrical feed-through and energy transfer between modes.The gyroscope system's stiffness will be modulated in a static way and will realize parametric amplification,thus,the electrical feed-through will be limited and response of drive mode will be amplified.Thus,error signals will be suppressed.Besides,through MATLAB numerical simulation and the modeling of Simulink digital system,it is noted by adjusting the parametric excitation parameters(frequency,amplitude and phase),the resonant frequency will be changed and quality factor will be improved.Hence,allowing harmonic forcing levels to be reduced whilst sustaining the response amplitude.Finally,the performance of the gyroscope will be improved.