Magnetic Beeline - Satellite Derived Attitude for Marine Navigation

Tom Ford, Mamoru Kuwata, Hisakatsu Itoh, D. Otsu

Abstract:	In the past, the heading of a ship has been provided with a redundant set of north seeking gyros. The function of these is to provide to the vessel uninterrupted and continuously smooth heading to be used as an input to a rudder control loop, and to the orientation function of a radar image. While these have proven to be reliable and have become the standard for shipboard navigation, GPS in conjunction with a magnetic sensor can provide a low cost and reliable alternative. The challenges posed to this system are threefold. First, the integrity of the combined GPS/magnetic solution must be ensured. Second, the high frequency noise in the combined system caused by multipath, satellite constellation changes and usual ship heave must be damped. Finally, the combined system must provide continuous heading, in spite of satellite blockages. This system uses a single axis attitude GPS sensor called Beeline, together with a shipboard magnetic sensor. Beeline uses L1 carrier observations generated from a pair of antennas connected to a single GPS receiver to provide azimuth and pitch with accuracies of 0.4 degrees one sigma, provided the satellite coverage is sufficient. This is a complementary pairing of two systems, one (Beeline) which is unbiased but with intermittent integrity errors and the other (magnetic sensor) with slowly moving biases but with good continuity. The output of the beeline is used to monitor and model the low frequency magnetic sensor biases. The corrected magnetic output is used ensure the integrity of the beeline ambiguity resolution and to provide continuous azimuth output to the vessels control system when the Beeline data is poor or unavailable. In this paper, the navigation problem is described, the solution to this problem is offered and tests used to validate the system are described.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1245 - 1255
Cite this article:	Ford, Tom, Kuwata, Mamoru, Itoh, Hisakatsu, Otsu, D., "Magnetic Beeline - Satellite Derived Attitude for Marine Navigation," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1245-1255.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In