Experimental Study of Two-channel UWB-OFDM Radar for Indoor Navigation with INS Integration

K. Kauffman, J. Raquet, Y. Morton, D. Garmatyuk

Abstract: There is a great need to develop alternative navigation sensors for situations where GPS is not available. In our previous work, we developed a set of navigation algorithms for a novel indoor/outdoor navigation sensor, a UWB-OFDM radar. The previously developed experimental prototype system was mounted on an indoor vehicle and used in combination with an HG1700 tactical grade INS to provide a position and velocity solution. The algorithms extracted stationary radar features from the environment and used the relative motion between the features and the platform to correct the inertial solution errors. This test experimentally validated the use of a UWB radar as a navigation sensor. However, due to technical limitations the radar was only able to operate in single channel mode. With a single channel available, the radar would intermittently stop tracking features and therefore stop providing error corrections. The accuracy of the error corrections applied was also greatly limited by the intermittently available features. In this paper, the radar has been upgraded to operate in two-channel mode to allow for more robust and reliable navigation. In addition, the transmitted OFDM symbol uses a random sub-carrier modulation. This spreads out the transmitted energy to the full 1GHz spectrum and allows the waveform to be a discrete approximation to a noise waveform, enabling the radar to operate in LPI/LPD and jamming scenarios of interest to many military applications. The previous single-channel navigation experiment is repeated, moving the platform through a hallway containing metallic reflective surfaces. The range and Doppler measurements to each tracked reflector are used as updates to the navigation filter, implemented as a modified EKF. The EKF combines the radar measurements with INS measurements to compute an optimal estimate of the platform position error. The navigation solution is compared for two scenarios: INS-only position and INS position corrected by the EKF error estimate. These two navigation solutions are compared to the true trajectory. In the end, this paper demonstrates that an all-weather UWB-OFDM radar combined with an inertial system can be a viable alternative navigation sensor in GPS-denied environments.
Published in: Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013)
September 16 - 20, 2013
Nashville Convention Center, Nashville, Tennessee
Nashville, TN
Pages: 756 - 761
Cite this article: Kauffman, K., Raquet, J., Morton, Y., Garmatyuk, D., "Experimental Study of Two-channel UWB-OFDM Radar for Indoor Navigation with INS Integration," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 756-761.
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