GPS Attitude Determination by Adaptive Kalman Filtering

R. Campana, L. Marradi, S. Bonfanti

Abstract:	This paper presents current results of a work carried out at LABEN (a FINMECCANICA Company) in the frame of an ESA research study on GPS-based Spacecraft Atti-tude Determination. The aim is to find an attitude deter-mination algorithm that could provide a high accuracy even in presence of large multipath errors. This algorithm would be implemented on the GPS Tensor TM space-qualified receiver and tested in the frame of the Argentine SAC-C mission. The Tensor receiver, provided by LABEN, will be primary sensor on the argentine SAC-C mission and will provide both navigation and attitude data to the on-board computer. An important part of the work was therefore dedicated to the simulation of the ef-fects of multipath, as seen by the receiver antennas on the reference SAC-C spacecraft configuration. Multipath in-duced differential phase measurement errors are simu-lated by an electromagnetic model that provides signal reflections and diffraction from a CAD model of the spacecraft. Due to the presence of a long boom on the re-ceiver antenna side, SAC-C presents a very challenging multipath environment. The design that currently shows best results is based on a Kalman filter attitude solution that uses differential phase measurements and an adaptive scheme based on meas-urement residuals. Three different algorithms, which are presented in the paper, have been evaluated within a SW simulation environment. The selection of the algorithm to be used on SAC-C is based on the results obtained in terms of estimation accuracy and required CPU load. Simulation results show that the filtering process is able to significantly reduce the effects of both receiver meas-urement noise and multipath colored noise with minimal increase in CPU load and to achieve more than 35% im-provement in estimation accuracy, compared to the appli-cation of a standard least-squares solution.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1979 - 1988
Cite this article:	Campana, R., Marradi, L., Bonfanti, S., "GPS Attitude Determination by Adaptive Kalman Filtering," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1979-1988.
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