Experimental Demonstration of GPS as a Relative Sensor for Formation Flying Spacecraft

The development of a GPS-based relative position and attitude sensing system in a laboratory environment is presented, with application to spacecraft formation flying. Previous papers have discussed the demonstration of spacecraft rendezvous and capture in two dimensions, in a fully functional indoor GPS environment using simulated spacecraft on an air-bearing table [1]. The work presented in this paper extends the previous GPS-based sensing to a formation of three prototype spacecraft, and experimentally demonstrates very accurate real-time solutions (≥ 2 cm and ≥ 0.5 deg errors) for the three relative vehicle positions and attitudes. In addition, candidate estimation architectures for the three vehicle formations are studied in simulation. Search-based techniques for carrier-phase integer ambiguity resolution are also demonstrated on simulation data.