Study On The Nonlinear Vibration And Mode Coupling Of The Miniaturized MEMS Butterfly Gyroscope

With the rapid development of micro-electro-mechanical systems(MEMS),MEMS gyroscopes have been widely used in aerospace,inertial navigation,intelligent electronics,automotive safety and other military and civilian fields.The butterfly gyroscope has become an important research direction in the field of MEMS gyroscope due to its advantages of easy processing,high sensitivity and environmental adaptability.The miniaturization design is very important for reducing volume,decreasing cost,reducing power dissipation and increasing output of the butterfly gyroscope.However,due to the reduction of the overall size of the MEMS gyroscope,the nonlinear vibration and the modal coupling are inhanced.The nonlinear vibration of operating modes causes the large drift of the natural frequency and supperessing the nonlinear vibration of operating modes is one way of further improving the detection accuracy.The modal coupling is the response of one mode caused by the input of the other mode.On the one hand,the modal coupling between operating modes needs to be suppressed,as it leads to the quadrature error of MEMS gyroscope directly.On the other hand,the dynamic characteristics of MEMS gyroscope can be effectively improved by sideband excitation based on the modal coupling between non-operating modes and operating modes.However,the research on nonlinear vibration and modal coupling of MEMS gyroscopes is rarely reported currently.In this paper,a miniaturized MEMS butterfly gyroscope is designed and fabricated.Then,the characteristics of the nonlinear vibration in the butterfly gyroscope are analyzed and a method of improving the dynamic characteristics of the nonlinear vibration is proposed from the aspect of the structure design.Also,a quadrature error suppression method is proposed based on the coupling mechanism between the operating modes.Finally,the characteristics of the sideband excitation in the butterfly gyroscope are studied and a method of adjusting the quality factor(Q)is proposed based on the sideband excitation.The main contents of this dissertation are as follows:1.The design,fabrication and working principle of the miniature butterfly gyroscope are introduced.Firstly,the structure and the working principle of the gyroscope are introduced.Then,the dynamic characteristics of the gyroscope are analyzed and the key dimensions of the gyroscope are designed and compared with the traditional butterfly gyroscope.Finally,the processing of the gyroscope is introduced.2.The characteristics of the nonlinear vibration in the miniature butterfly gyroscope are studied.Firstly,the generating mechanism of the nonlinear vibration is introduced.Then,the nonlinear vibration of operating modes is modeled and analyzed respectively.Also,the method of suppressing the nonlinear vibration of operating modes is proposed from the aspect of the gyroscope design.3.The generating mechanism and the suppression method of the quadratue error are studied.Firstly,the mechanism of the quadrature error and zero-offset output of the gyroscope is introduced.Then,the influence mechanism of the quadrature error on zero-offset output is analyzed.Finally,a method is proposed to suppress the quadrature error based on the modal decoupling.4.A method of adjusting the Q factor of the sensing mode based on the sideband excitation in the miniature butterfly gyroscope are studied.Firstly,the generating mechanism of the sideband excitation is introduced.Then,the theoretical model and analysis of the sideband excitation are carried out.Finally,a method of adjusting the Q factor is proposed based on the sideband excitation.