Study On Quadrauture Correction And Mode-matching For MEMS Ring Gyroscopes Under Force-to-rebalance Operation

Ring resonant gyroscope is one of the most promising MEMS gyroscopes.This paper takes the ring resonant gyroscope as the research object,and uses the orthogonal correction to eliminate the stiffness coupling and the electrostatic tuning to realize the mode matching.On this basis,simulations and experiments are carried out to verify the analysis.The research content is as follows:(1)The basic structure and working principle of ring resonator gyroscope are discussed.This paper discusses the modal characteristics of the ring resonator and the selection of the working modes based on the performance.Typical methods of mode matching for driving and sensing modes of ring gyroscope are introduced.Basic equations of motion of the ideal ring resonator are derived.On this basis,the operating principle of full angle mode and force re-balance mode are discussed briefly.(2)Error of ring resonator gyroscope under mode mismatch is analyzed.This paper discusses the error model under the mode mismatch from the frequency error and the damping error.The influences of various error sources of the resonator on the force re-balance mode are analyzed.Two error measurement methods based on the sweep response and the ring down method(for high Q-value harmonic oscillator)are studied,and the theory is verified through simulations and experiments.The experimental results of both methods are close to the simulation results,which proves the feasibility of the measurement method.(3)The quadrature correction of the ring resonator gyroscope.Two kinds of quadrature correction methods are discussed,which are based on the force feedback and the electrostatic negative stiffness effect to decouple the stiffness.The simplified linear model and its transfer function are derived,and the multi-physical field finite element simulation is carried out.Finally,two experiments are designed to verify the theories.(4)Online identification of frequency split of ring resonant gyroscope.Two typical mode matching methods,the pilot tone method and the quadrature modulation method,are introduced.The control block diagrams are discussed and the algorithm simulations are carried out with the same parameters.A frequency split identification method based on noise power spectrum estimation is proposed.The accuracy is verified by both simulations and experiments.(5)Test of ring resonator gyro.The experimental data show that the zero bias of gyro is reduced by 90% under the condition of mode matching.