GPS Attitude Determination of Spin Stabilized Satellites

Manuel Martin-Neira, Rafael Lucas

Abstract:	A GPS Integrated Navigation and Attitude Determi- nation System (GINAS) for spin stabilised satellites is presented in this paper. The sensor consists of an ar- ray of two antennas connected to a GPS receiver unit which performs code and carrier phase measurements. The basic observable used for attitude computation is the integrated doppler count, although pseudoranges are also needed. Thus, either a C/A or a P code GPS receiver can be utilised in this sensor, being the all- in-view type GPS receivers the most suitable for this application. The paper describes the connection between the inte- grated doppler counts and several parameters which characterise the dynamic motion of a spin stabilised satellite. Axial symmetry of the satellite is assumed in the dynamic model for simplicity but the same method could be extended to a more general case. The GPS attitude sensor outputs, for this simple case, the rates of rotation around the principal body axis and around the inertial direction defined by the angular momen- tum vector of the satellite, the angle of nutation, the components of the angular momentum vector and the phase of the rotations at an initial epoch, Prom these parameters, the instantaneous orientation of the satel- lite is derived based on adaptive deterministic meth- ods. The use of integrated doppler count as alternative to carrier phase minimises errors coming from unbal- anced antenna electrical paths, cycle slips and multi- path, while makes the sensor performance very robust. Results are presented, at simulation level, and also us- ing real GPS hardware and a GPS signal simulator, which confirm the expected behaviour of the GINAS system.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	757 - 765
Cite this article:	Martin-Neira, Manuel, Lucas, Rafael, "GPS Attitude Determination of Spin Stabilized Satellites," Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992), Albuquerque, NM, September 1992, pp. 757-765.
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