Exploitation of Cooperative GNSS/IMU Systems for Positioning within UxV Swarms

Simon Batzdorfer, Ulf Bestmann, Alexander Schwithal, Martin Becker, Prof. Peter Hecker

Abstract:	The usage of unmanned air (UAV) or ground (UGV) vehicles for different applications has been increased in recent times. The vehicles can be used for exploration and search and rescue applications in areas which are destroyed by natural or industrial disasters. Due to time efficient operation, swarms of unmanned air and/or ground vehicles (UxV) could be used to cope with large areas. Independent from special application, the knowledge of the absolute position of each rover als well as the relative position between them is indispensable. Absolute positioning is essential for precise controlling and an exact mapping of exploration results. Positioning using Global Navigation Satellite Systems (GNSS) with high demands towards accuracy is state of the art using GNSS phase measurements and reference stations to be supported with correction information. Such information may be not available due to loss of reference stations in catastrophic scenarios. Thus standalone GNSS accuracy is assumed for the swarm participants. Following this assumption, this paper will investigate different techniques that aim at the relative positioning between the participants. Therefore, interchanged GNSS raw measurements are used for determining three dimensional baselines between the UxVs. This approach has the advantage that certain error components are compensated. The challenging difference is that the UxVs do not have a well known fixed position and geometry those varies with time. To provide reliable position information with high data rates and to compensate GNSS outages, a custom-build Inertial Measurement Unit (IMU) has been integrated into the UxVs. Finally, the IMU provides accurate attitude information that is mandatory for UxV control and sensor data analysis. The coupling of GNSS and inertial measurements is realized based on a navigation software framework at the IFF. A tight coupled approach has been chosen using GNSS raw measurements which offers the possibility to apply UxV autonomous failure detection and exclusion methods as well as using less than four GNSS raw measurements for aiding the GNSS/IMU coupling filter.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	3835 - 3841
Cite this article:	Batzdorfer, Simon, Bestmann, Ulf, Schwithal, Alexander, Becker, Martin, Hecker, Prof. Peter, "Exploitation of Cooperative GNSS/IMU Systems for Positioning within UxV Swarms," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 3835-3841.
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