MEMS-IMU Error Analysis Compensation Method And Experiment Research

In order to implement the attitude measurement of the tactical ballistic trajectoryweapon, this dissertation focused on the research of the Micro-Electro-MechanicalSystems Inertial Measurement Unit(MEMS-IMU) error mechanism and correspondingcompensation method under the actual combination condition, including large angle rate,acceleration and temperature variation. Since the principal of the MEMS inertial sensorwhich comprised the MEMS-IMU are different from the other kinds of inertial sensors,the traditional compensation models are not optimized. The research on theMEMS-IMU error mechanism is the basis of the compensation method.This dissertation firstly introduced the principle of MEMS-IMU and the fabricatedtactical grade accuracy MEMS-IMU. The errors of the MEMS-IMU were estimatedunder the certain condition to provide the importance of certain errors includingtemperature drift and g sensitivity. Part of this dissertation would focus on theinterpretation of these errors.Then, this dissertation proposed a statistical parameter method to analyze thesensor output error caused by the manufactured dimension variation. It connected thevery beginning of the sensor fabrication and output of the sensor. It also can predict therange of the output error with the certain fabrication process. The possibleinterpretations of the accelerometer thermal drift based on the width parameters and thefabrication process were analyzed. The contribution of the stiffness asymmetry of theU-springs of the structure and relative displacement caused by the mismatch in thermalexpansion coefficients between the Pyrex glass substrate and heavily boron-dopedsilicon structure was investigated, modeled and simulated. The analytical model andmultiphysics simulation model were established to calculate and simulate the thermaldrift. The temperature experiments were carried out to compare and verify the analysisresult.Next, this dissertation analyzed the possible error mechanism of the thermal driftand g-sensitivity of doubly decoupled MEMS gyroscope. The phenomenon of thenon-zero detection capacity difference caused by the twist of the center mass, whichwas caused by the acceleration force and driven force and the U-spring width variation,was mainly investigated. The finite element model of the gyroscope's structure was established and simulated. The simulation result of zero rate output, thermal drift andg-sensitivity were given and compared with the analysis value and experiment result.Furthermore, this dissertation proposed a magnetometer aid over-range rotationrate combination measurement method which can compensate the large angle rate errorcaused by the gyroscope. The overall MEMS-IMU calibration method was proposedbased on the analysis of the error principle above. A compensation method for thecalibration of the MEMS-IMU was also designed to improve the performance ofMEMS-IMU.Finally, this dissertation introduced the successful flight experiment which verifiedthe entire work of this dissertation. The overall compensation method, themagnetometer aid method and the analysis of the error of MEMS-IMU were verified bythis experiment.