A New Method for Electronic Compass Magnetometer Calibration for Improving Azimuth Calculation in Magnetometer/GPS Integrated System

Hang Guo, Donghyun Kim, Richard Langley, Min Yu, Chengwu Zou, Wenwen Huang

Abstract:	In this paper, a new method for magnetometer calibration is introduced. The procedure is involved with several steps. Firstly, hard/soft iron errors in the magnetometer measurements are computed. The results showed a great reduction in error from tens of degrees to several degrees. Then, least-squares estimation using Fourier series parameters is carried out to estimate residual errors due to varying environmental factors. 1.51 degrees of residual standard deviation of the calibration was obtained. After applying the calibration results to predict azimuths for the whole test driving route, the results showed that the residual standard deviations was 3.46 degrees excluding a few magnetic disturbances due to the environment changing as car moves. Also in this paper, the continuous azimuth calculation of a magnetometer/GPS integrated system was finished. As the mutual benefit, a magnetometer has provided the continuous, high rate azimuth, and bridged the gaps of GPS azimuths. And GPS azimuth eliminated the magnetic disturbances successfully in our field test. As a result, the azimuth accuracy of below one degree in STDEV is obtained. Finally, magnetic azimuth disturbance is expressed as a first-order Gauss-Markov process and combined with the magnetic dynamic equation. The magnetic azimuth calculation results were merged into a Kalman Filter to predict the car azimuth for the purpose of bridging the gaps of GPS azimuths. In the field tests for car navigation, magnetometer data were recorded at a 69.9 Hz. Test results showed about 3 degrees accuracy in the azimuth estimates without GPS aiding.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	1641 - 1648
Cite this article:	Guo, Hang, Kim, Donghyun, Langley, Richard, Yu, Min, Zou, Chengwu, Huang, Wenwen, "A New Method for Electronic Compass Magnetometer Calibration for Improving Azimuth Calculation in Magnetometer/GPS Integrated System," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 1641-1648.
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