High Precision Real-Time Navigation for Spacecraft Formation Flying

S. Leung, O. Montenbruck

Abstract:	In view of intensifying interest in spacecraft formation flying and autonomous rendezvous & docking capability for future space missions, a high precision real-time GPS navigation system has been developed and validated at the German Space Operations Center (DLR/GSOC). The system employs a decentralized and scalable architecture in which each spacecraft is equipped with a L1-C/A code GPS receiver, a pair radio modems and a navigation computer. Using sophisticate real-time navigation algorithms, the system is able to provide accurate absolute and relative state estimations onboard formation flying spacecraft. Hardware-in-the-loop simulations have demonstrated real-time relative navigation accuracies on the sub-centimeter and µm/s level for baselines of up to 10 km. The highly accurate relative state, in particular for the relative velocity estimation, enables the system to fulfill the requirements for precision formation control. Due to the limited processing power available onboard the navigation computer, the state updates only at 10-30 s intervals depending on the number of spacecraft in the formation. To increase the data output rate, the system interpolates and output the filter solutions at 1 Hz to bridge the estimation gaps. The more frequent update makes the system suitable for close proximity autonomous spacecraft operation.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	2182 - 2193
Cite this article:	Leung, S., Montenbruck, O., "High Precision Real-Time Navigation for Spacecraft Formation Flying," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 2182-2193.
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