Research On Structure Design And System Simulation Of Integrated MIMU

Micro inertial measurement unit(MIMU)is a kind of micro inertial system which can measure the inertial parameters in six directions.It has a great development prospect in civil and military fields.In this paper,based on the basic theory of MIMU,an integrated MIMU structure is designed,which is composed of a capacitive accelerometer and a vibrating gyroscope.The simulation and analysis of the integrated MIMU system are carried out by combining the measurement and control circuit.The main research of the dissertation are as follows:(1)The development status of accelerometers,gyroscopes,MIMU and integrated MIMU at home and abroad are analyzed;based on the principle of micro inertial sensors,the dynamic analysis of capacitive accelerometer and vibrating gyroscope is carried out,and the basic equations of motion of capacitive accelerometer and vibrating gyroscope are obtained;the common comb structure and related driving modes and detection methods of capacitive accelerometer and vibratory gyroscope are summarized,which lays the foundation for the structural design and simulation of the integrated MIMU.(2)Based on the analysis of domestic and foreign MIMU integration scheme,the integrated structure of accelerometer gyroscope is proposed,which can measure the acceleration and angular velocity of single direction simultaneously;the crab legs beams,straight beams and rectangular beams are chosen as the supporting beams of the integrated MIMU structure,coupling effect between driving mode and detection mode is eliminated,the disturbance caused by the accelerometer detection mode in the horizontal axis is reduced;aiming at the problem that the accelerometer detection mode is affected by the driving mode and detection mode,the structure adopts the comb structure with equal height and unequal height,and adopts the differential detection method of variable pitch and variable area type,ensure the accuracy and precision of the measured acceleration;based on the above design principles,the main dimension parameters of the integrated MIMU structure are determined(3)In order to verify the rationality of the integrated MIMU structure,the finite element software is used to analyze the micro displacement,gravity analysis,modal analysis,harmonic response analysis and transient response analysis.The displacement sensitivity of the acceleration and angular velocity of the structure is obtained by the micro displacement analysis,which provides an important reference for the design of the measurement and control circuit;the maximum stress intensity of the structure in the free state is 449KPa,which can fully satisfy the requirement of theoretical stress intensity;the amplitude frequency response curve of each frame is obtained by the harmonic response analysis,and then the cross sensitivity between the integrated MIMU structure is calculated,which lays the foundation for improving the detection accuracy of the integrated MIMU system;the transient response analysis shows that the structure can withstand the transient impact load of 100g.(4)Analysis of capacitive accelerometer and gyroscope common control circuit based on the measurement and control system are designed for integrated MIMU structure,and analyzes the working principle of the phase-locked loop system module,AGC module,carrier module,modulation module,demodulation module.The Simulink modeling and simulation based on Y axis gyroscope driving system,detection system and Y axis accelerometer system,the integrated MIMU system for measurement of angular velocity and acceleration of the scale factor is 8.552mV/°/s and 65mV/g respectively.The simulation results show that the integrated MIMU system is feasible,and the gyro drive system is robust.