Passive Navigation Using Local Magnetic Field Variations

J.M. Wilson, R.J. Kline-Schoder, M.A. Kenton, P.H. Sorensen, and O.H. Clavier

Abstract:	In the event that ground-based and satellite-based navigational aids become unavailable, an inexpensive means of providing continued navigation for aerial vehicles would be valuable. Utilizing an existing map of local variations in the magnitude of the Earth's magnetic field, in combination with magnetic measurements taken in flight, we have developed a magnetically-aided deadreckoning system that provides such a navigation solution. The resulting navigation system is completely passive. This method is expected to work best in geographic regions with sufficient spatial variation in the magnetic field. In addition, because local spatial variations in the magnetic field decrease with altitude, the method will work best for altitudes less than an upper limit that is dependent on the quality of magnetic measuring equipment used. Position accuracy using this method is sensitive to the accuracy of the magnetic field measurements in the aircraft and to the magnitude of temporal variations in wind speed and direction. Flight data taken in gusty conditions with only modest efforts to calibrate out magnetometer errors has yielded typical errors between 600 and 1200 meters for flight durations in excess of 1 hour. The position-update algorithm utilized for this navigation approach is generally applicable using any measurable scalar quantity for which a spatial map exists. One such example is vehicle height above terrain in a region with sufficient elevation variations. Combining a terrain map with the use of a sensor that detects vehicle height above ground would yield position information in a similar manner to the use of magnetic magnitude in the results reported here.
Published in:	Proceedings of the 2006 National Technical Meeting of The Institute of Navigation January 18 - 20, 2006 Hyatt Regency Hotel Monterey, CA
Pages:	770 - 779
Cite this article:	Wilson, J.M., Kline-Schoder, R.J., Kenton, M.A., Sorensen, P.H., Clavier, O.H., "Passive Navigation Using Local Magnetic Field Variations," Proceedings of the 2006 National Technical Meeting of The Institute of Navigation, Monterey, CA, January 2006, pp. 770-779.
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