Development of a Low Cost Multiple GPS Antenna Attitude System

Chris Hide, James Pinchin, David Park

Abstract:	Current research for multiple antenna GPS attitude determination is focused on obtaining high accuracy attitude using low cost receivers and low cost antennas. Measurements from low cost sensors typically suffer from factors such as increased measurement noise, multipath, antenna phase center variation and cycle slips. This paper describes the rapid development of a low cost attitude determination system for use on an Unmanned Aerial Vehicle (UAV) that will be used as in input for georeferencing an on-board camera. The filter was developed using a plug-and-play filter design that allows combinations of measurements and states to be easily implemented in an Extended Kalman Filter. Using such an approach has the significant advantage for integrated systems where, for example, attitude measurements can also be used as measurement updates to aid inertial navigation systems (INS) in a tight coupled architecture. An overview of the plug-and-play methodology is given along with a description of the constrained LAMBDA algorithm used for ambiguity determination. This paper shows results from three trials: two with receivers connected to a Spirent Hardware simulator, and a third real-world test using a vehicle installed with a Novatel SPAN integrated GPS/INS system to provide a reference. The datasets are used to identify the primary issues related to using low cost GPS receivers for attitude determination. It is demonstrated that using hardware simulation without modelling antenna or multipath errors, heading accuracy of 0.05 degrees RMS and tilt accuracy of 0.09 degrees RMS can be achieved on a 2m baseline. It is also shown that static heading accuracies of 0.04 degrees are achieved on a 2.38m baseline using realworld data. Initial tests under dynamic conditions have achieved 0.30 degrees, however it is anticipated that with improvements in cycle slip detection and antenna type, this should be improved. The paper concludes with future suggestions that should improve the kinematic performance of the system.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	88 - 95
Cite this article:	Hide, Chris, Pinchin, James, Park, David, "Development of a Low Cost Multiple GPS Antenna Attitude System," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 88-95.
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