Abstract This paper describes a carrier-phase differential GPS approach for real-time relative navigation of LEO satellites flying in formation with large separations. These applications are characterized indeed by a highly varying number of GPS satellites in common view and large ionospheric differential errors, which significantly impact relative navigation performance and robustness. To achieve high relative positioning accuracy a navigation algorithm is proposed which processes double-difference code and carrier measurements on two frequencies, to fully exploit the integer nature of the related ambiguities. Specifically, a closed-loop scheme is proposed in which fixed estimates of the baseline and integer ambiguities produced by means of a partial integer fixing step are fed back to an Extended Kalman Filter for improving the float estimate at successive time instants. The approach also benefits from the inclusion in the filter state of the differential ionospheric delay in terms of the Vertical Total Electron Content of each satellite. The navigation algorithm performance is tested on actual flight data from GRACE mission. Results demonstrate the effectiveness of the proposed approach in managing integer unknowns in conjunction with Extended Kalman Filtering, and that centimeter-level accuracy can be achieved in real-time also with large separations.
Highlights ► CDGPS for real-time relative positioning of distant LEO satellites. ► An Extended Kalman Filter is used for the float estimate. ► The LAMBDA method is used for integer ambiguity fixing. ► A closed-loop algorithm feeds back the “fixed” estimates to the EKF. ► Cm-level accuracy proved on GRACE flight data with separations of 270km.
Validation on flight data of a closed-loop approach for GPS-based relative navigation of LEO satellites
Acta Astronautica ; 86 ; 126-135
2013-01-15
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Relative Navigation of Formation Flying Satellites
NTRS | 2002
|Relative Navigation of Formation Flying Satellites
NTIS | 2002
|Relative Navigation of Formation-Flying Satellites
NTRS | 2002
|