From Shipboard Landing to Aerial Refueling: Autonomous Relative Navigation

Shahram Moafipoor, Lydia Bock, Jeffrey A. Fayman

Abstract:	In this paper, we present experimental results of a relative navigation system developed to support autonomous relative navigation of manned and unmanned UAVs in demanding applications such as aerial refueling and autonomous landing. What is common to these applications is the interaction between two or more vehicles. We refer to two vehicles as Primary and Secondary depending on where the relative navigation calculations are performed. Relative navigation is provided between a single Primary unit and multiple Secondary units. The core of the GPS/IMU based system is an Extended Relative Navigation Filter, Rel-EKF, that is updated by the relative position vector provided by the GPS moving baseline ambiguity fixing technique. In the system, raw observations from the GPS and IMU of the Secondary are transmitted to the Primary through a datalink. The Primary uses this data to determine its Relative Position, Navigation, Time (PNT) to the Secondary. From a generic perspective, the system can utilize relative distance/attitude measurements from any non-GPS-based sources to update the Rel-EKF and calibrate relative navigation equations. Autonomous operations require that the total system error over a specific time interval be provided at the desired accuracy with a probability of 0.95%. Experiments began by validating system accuracy as a function of sensor configuration. Ground tests were conducted with different IMU’s grades and several configurations of GPS including civilian and SAASM sensors. Following performance analysis, we tested the system for use in shipboard landing and aerial refueling applications on UAV flights. Total system error and risk allocation analyses were performed for the data collected. The relative position, velocity, and attitude accuracy, under normal conditions, were expected to be at an accuracy of 0.25m,0.1m/s, and 0.5?, respectively. Future developments of the system include assured system integrity under GPS-denied conditions, including jamming and spoofing.
Published in:	Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018) September 24 - 28, 2018 Hyatt Regency Miami Miami, Florida
Pages:	1691 - 1702
Cite this article:	Moafipoor, Shahram, Bock, Lydia, Fayman, Jeffrey A., "From Shipboard Landing to Aerial Refueling: Autonomous Relative Navigation," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 1691-1702. https://doi.org/10.33012/2018.15896
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