Research Of Anti-Magnetic Interference Algorithm Of Mems-based Attitude Reference System

AHRS(Attitude and Heading Reference Systems) has great application prospects in civil areas. AHRS consist of MEMS gyroscopes, accelerometers and magnetometers on all three axes and AHRS can effectively restrain MEMS gyro's low accuracy and large gyroscope drift during attitude algorithm. However the magnetometer is vulnerable to external magnetic field disturbance, thus it might produce adverse effect to the fusion results, besides, silicon material and structural properties of MEMS gyroscope are sensitive to temperature which causes larger drift of MEMS gyroscope. The main content and work of this thesis are given as follows:1. In the thesis, the basic theories of attitude calculation are first introduced, including common coordinates in inertia system, attitude matrix, quaternion and rotation vector attitude algorithms and so on. Besides, strapdown attitude algorithm is initially described.2. The composition of AHRS and the attitude calculation are introduced. After showing the attitude solutions with MEMS gyroscopes and accelerometers, magnetometers separately, the KF is used to calculating the carrier's attitude.3. Analyses the source of temperature error. It indicates that resent frequency and quality factor are the main factors which influence the motion displacement and structure sensitivity. The resonant frequency will generate excursion and quality factor will change with temperature variation,which will magnify the original error and it will bring great influence on the output precision. Then, we introduce thermal error compensation algorithm model.4. The character of disturbing magnetic field is analyzed based on analyzing the error of magnetometer, and is classified into carrier magnetic field and environmental magnetic field. There are more compensation algorithm for carrier magnetic field such as the least squares algorithm based on elliptic hypothesis while less algorithm for environmental magnetic field. Therefore some work was done on the study of the topic and an anti-magnetic strategy was raised in the thesis.At the end, a large number of experimental results prove that the temperature compensation algorithm of MEMS gyroscope and the anti-magnetic strategy proposed in this thesis are effective and have practical value.