Software Simulation Tests and Results for Nano-Satellite Formation Flying

Q. Marji, R. Tsoi, M.E. Cannon, and R.E. Zee

Abstract:	The Canadian Advanced Nanospace eXperiment (CanX) Program of the Space Flight Laboratory at the University of Toronto’s Institute for Aerospace Studies (UTIAS/SFL) has allowed Canadian engineering researchers to test nano-scale satellites in space. The current phase of the program is to demonstrate the capability for formation-flying using two nano-satellites known as CanX-4 and CanX-5. The nanosatellites are designed to fly simultaneously in Low Earth Orbit (LEO) to demonstrate the possibility for on-orbit formation-flying involving precise relative navigation and control using several different configurations while in orbit. To make these maneuvers possible, the relative positioning accuracy required by the mission is less then 10 cm. The Global Positioning System (GPS) is capable of providing such accuracy when Carrier Differential GPS (CDGPS) techniques are used. In this paper, the uses of such techniques are demonstrated to estimate the relative position and velocity between the nano-satellites. To demonstrate the use of CDGPS for precise relative navigation, a GPS measurement software simulator, SimGNSSIITM, has been modified to replicate the GPS conditions in a space-borne environment. The GPS simulated observables are then processed using GPS carrier phase software, FLYKIN+TM, for precise relative position determination. The algorithms used by the software have been enhanced for formation flying purposes, whereby the Moving Base Station (MBS) capability has been implemented to support applications with a non-static reference station. In this paper, two test scenarios are chosen with different baseline separations. The separation varies between 100 m – 2 km. Simulation results indicate that the 3D RMS positioning error for the 100 m and the 2 km test scenarios are about 2 cm. As for the velocity, a 3D RMS of about 2 mm/s is achieved for both test scenarios.
Published in:	Proceedings of the 2007 National Technical Meeting of The Institute of Navigation January 22 - 24, 2007 The Catamaran Resort Hotel San Diego, CA
Pages:	628 - 636
Cite this article:	Marji, Q., Tsoi, R., Cannon, M.E., Zee, R.E., "Software Simulation Tests and Results for Nano-Satellite Formation Flying," Proceedings of the 2007 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2007, pp. 628-636.
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