Structural Design And Simulation Analysis Of MEMS Vibratory Gyroscope For Automotive Applications

Compared with traditional mechanical gyroscope,MEMS vibratory gyroscope has the advantages of smaller size,lower cost,and lower power consumption,and is widely used in the fields of intelligent driving and safety control of automotive.However,the complex driving conditions will impose quite harsh environment on the micro-gyroscope.Affected by the processing errors and harsh working conditions(such as vibration,shock,thermal cycling,etc.),the micro-gyroscope still has large errors in vehicle attitude measurement and navigation.Based on the performance requirements of the micro-gyroscope in automotive applications,this paper proposes a dual-mass fully decoupled 2-DOF sensing structure design model of the microgyroscope.An equivalent dynamic model of the micro-gyroscope is established,and the bandwidth,anti-interference ability,working robustness are effectively improved through the dual-mass fully decoupled design,the modal frequency matching design and the 2-DOF sensing module design.(1)The dynamic model of the single-mass gyroscope is established,and the steady-state displacement response of the driving mass and the sense mass is derived.The restriction relationship between mechanical sensitivity and bandwidth is analyzed,and the influence of coupling error and common mode interference on the performance of micro-gyroscope is studied.(2)A novel structure of dual-mass fully decoupled micro-gyroscope is proposed.The fully decoupled design can reduce the coupling error of the structure,and the dual-mass driving for differential detection can reduce the common mode interference.The equivalent decoupling dynamic model of the novel structure is established.The coupling elastic structure with negative stiffness is designed,and the frequency matching of the driving mode and the sensing mode is realized by optimizing the size parameters of the sensitive elastic structure(anti-phase driving frequency: 6149 Hz,anti-phase sensing frequency: 6194Hz),while effectively increasing the modal frequency difference(1366Hz)between anti-phase and in-phase motion to improve the anti-interference ability of the structure.(3)In order to improve the bandwidth and robustness of the micro-gyroscope,a dual-mass fully decoupled micro-gyroscope with 2-DOF sensing module is designed.The equivalent dynamic model of the 2-DOF sensing system is established,the gain and bandwidth of the system are obtained by the transfer function in the zero-damping state,and the structural parameters are optimized by genetic algorithms to obtain the micro-structure with high sensitivity and wide bandwidth.The frequency response of the structure is calculated by FEA,and the 3d B bandwidth of the 2-DOF sensing micro-gyroscope is 210 Hz,which is much larger than the 40 Hz of the 1-DOF sensing micro-gyroscope.The influence of processing errors and damping changes on the performance of the gyroscope is analyzed: the 2-DOF sensing microgyroscope reduces the mechanical sensitivity attenuation caused by the processing error from 80% to 2 %,reduces the attenuation caused by the damping changes from 75% to 5%.This verifies the high sensitivity,wide bandwidth and well robustness of the proposed structure.