Key Technologies Research On The Bias Stability Improvement Of The MEMS Disk Resonator Gyroscope

High-precision Microelectromechanical System(MEMS)gyroscope is the core device in the fields of unmanned systems,autonomous navigation and intelligent equipments etc.and it has urgent needs and broad application prospects.The MEMS disk resonator gyroscopes(DRG)is a vibrating gyroscope based on the Coriolis effect.In addition to the advantages of small volume,low cost and mass production which is commom advantages of micro gyroscopes,the DRG has a fully symmetrical resonant structure,a central fixed anchor and a large number of internal holes,which makes it has better robustness to processing,better temperature stability,more flexible electrode configuration and larger capacitive area.Thus,the DRG is the most promising micro gyroscopes solution up to now.At present,the performances of the MEMS DRG are still need to be improved,and there is still a lack of systematic research on performance improvement.In this paper,the research on the theory and key technologies of the bias stability improvement of the MEMS DRG is carried out to realize the high-performance gyroscope prototype.The main research contents of this paper are as follows:1.The basic theoretical model of MEMS DRG is established and it lays a theoretical foundation for the optimization of the gyroscope.According to the structural characteristics and working principle of the MEMS DRG,the distributed-parameter dynamic model of the gyroscope is established with the component modal synthesis method,which solves the problem of the theoretical analysis of the vibration mode of the complex disk resonator structure.Meanwhile,based on the lumped parameter equivalent method,the lumped-parameter dynamics model under ideal condition and with structural error are established.Besides,the effects of gyroscope structure error and circuit phase error are studied.2.The basic theory and key technologies for the bias stability improvement of the MEMS DRG are proposed,which provides a specific direction for the research of highperformance gyroscope.Noise and bias drift are the main influencing factors of the bias stability.Through the noise analysis and bias drift mechanism analysis the gyroscope's noise model and bias drift model are established.According to these models,the basic theory and key techniques such as effective displacement ratio improvement,quality factor improvement,frequency and damping matching are proposed for the reduction of the gyroscope's noise and bias drift.3.The research on the key technologies for the bias stability improvement of the MEMS gyroscope are carried out,and the performance of the gyroscope is effectively improved.In the aspect of the effective displacement ratio improvement,the nonlinear theoretical model of the MEMS DRG is established.And based on the vibration amplification effect,an electrode arrangement scheme combining driving with inner electrodes and sensing with outer electrodes is proposed,which breaks the nonlinear effect on the effective displacement ratio of the gyro and realizes the great improvement of the gyroscope's effective displacement ratio.In the aspect of Q factor improvement,the Q factor improvement theory and the Q factor improving method based on the massstiffness decoupling are perfected,which effectively improve the gyroscope's Q factor.In terms of the frequency and damping matching,the frequency trimming and matching theory is deduced and the multi-electrode synchronous trimming is proposed for the reduing the influence of the electrodes error.Meanwhile,the frequency is accurately matched with the dither signal monitoring method.Besides,the damping trimming and matching theory and method based on the energy dissipation method is derived and verified.4.A high-performance MEMS DRG prototype is developed,and its performance reaches the international advanced level.Based on the relevant theories and techniques proposed in this paper,a high-performance gyro prototype is obtained through continues optimization,and a comprehensive performance test is carried out.Testing results show that the gyroscope's range reaches ±300o/s and the resolution reaches 0.0002o/s.In seven repeated tests,the average level of bias instability at room temperature is 0.077o/h,and the angular random walk(ARW)is 0.013o/?h.According to public reports at home and abroad,this performance reaches the international advanced level in the MEMS disk resonator gyroscopes.Furthermore,it can be learnt that the MEMS DRG has high precision and good repeatability,showing great performance potential.