Collaborative GPS/INS Navigation in Urban Environment

F.Berefelt, B.Boberg, J.Nygårds, P.Strömbäck and S.-L. Wirkander

Abstract:	The Swedish Defence Research Agency is currently conducting research aiming at the creation of a Net work Based Defence (NBD). This research includes areas such as GPS/INS navigation and collaboration of Unmanned Ground Vehicles (UGV:s). A large problem with navigation systems that use GPS is that, due to the possibility of satellite out ages, there are many occasions when the GPS receiver fails to deliver enough information to support an error free navigation. In this paper, techniques will be presented to increase position accuracy and navigation robustness in an urban environment by means of collaborative navigation. When a vehicle is navigating in an urban environment, lines of sight (LOS) to satellites will often be blocked. However, two vehicles at different locations can have different sets of visible satellites, and by collaboration the satellite information can be shared between the vehicles, which results in better navigational performance. The three collaborative techniques investigated in this paper are based on communication between the two vehicles, as well as measurements of their relative range or range vectors. In many ways the techniques are similar to using pseudolites, but with the important difference that here the pseudolites are mobile and also navigating. The case with two collaborating vehicles is considered. Both vehicles are equipped with complementary GPS/INS navigation tools using extended tightly coupled Kalman filters. When the vehicles are not collaborating with each other, their observations consist of acceleration and angular velocity measurements for the INS, together with pseudoranges as measured by the GPS receiver. An alternate method for acquiring accurate and robust navigation of a single vehicle in urban environments is Simultaneous Localization and Mapping (SLAM). In SLAM, a range measuring device (e.g. a laser range finder) is used to extract features from the environment. Accurate navigation will be accomplished as long as the features are correctly associated. A comparison between this technique and the collaborative GPS/INS methods mentioned above is also done in this paper. Simulations for a carefully chosen urban scenario are performed. The results indicate increased accuracy when using the investigated algorithms. Collaborative navigation opens up for cheap navigational platforms where several relatively simple vehicles can achieve the same performance as expensive and complex platforms.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	1114 - 1125
Cite this article:	F.Berefelt,, B.Boberg,, J.Nygårds,, P.Strömbäck,, Wirkander, S.-L., "Collaborative GPS/INS Navigation in Urban Environment," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 1114-1125.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In