Study On The Structural Vibrating Nonlinearity Of The MEMS Tuning Fork Gyroscope And Its Suppression Technique

Silicon micro-machined gyroscope has an extensive application prospects in both military and civil fields for its advantages such as small size,light weight and low cost.It becomes increasingly attractive over the world since its arrival.This paper focuses on the vibrating nonlinearity of the sensitive structure of the double-mass line-vibration MEMS tuning fork gyroscope.Firstly,the structure and operation principle of the gyroscope are illustrated,And its mechanical model is presented with the second order mass-spring-damper harmonic systems,the cubic nonlinear stiffness is introduced,and the Duffing equation is used to describe the nonlinear dynamics of the gyroscope,which is solved by multiple scales method.Secondly,this paper focuses on the vibrating nonlinearity of the drive mode of the gyroscope.The stiffness of the drive beam is obtained by energy method and ANSYS simulation tool,meanwhile,the stiffness of the comb is obtained by theoretical analysis.The results show that the stiffness of the beam is much larger than that of the comb.Therefore,the nonlinear stiffness of the beam is the main reason for the vibrating nonlinearity of the drive mode of the gyroscope.The mathematical relation between the vibrating nonlinear coefficient and the drive amplitude threshold before the nonlinear hysteresis arises is derived.An innovative method to measure and characterize the nonlinear coefficient of the gyroscope is presented.Based on the nonlinear coefficient determined by the experimental data,the amplitude threshold is obtained,which agrees well with the experimental results.Thirdly,the sensitive structure of the line-vibration MEMS tuning fork gyroscope is designed and implemented.The parameters of the structure of the gyroscope are confirmed.The design of the structural beam,modal error compensation,the ability of resisting overload are discussed.The layout of the gyroscope are designed.The partial technology and packaging of the gyroscope are given.Finally,the structure performance of the gyroscope is tested.The nonlinear coefficient of the gyroscope is reduced to 1/270,and the drive amplitude threshold of the gyroscope increases about 21.83 times than before.The results agrees well with the simulation data.