Passive Ranging for UAV Sense and Avoid Applications

*† ‡ Unmanned Air Vehicles (UAVs) are currently not authoriz ed by the Federal Aviation Administration to operat e freely within the National Airspace (NAS) due to the lack of an onboard system capable of providing an “equivalent level of safety ” (ELOS) to manned aircraft regarding the ability to “sense and avoid ” (SAA) other aircraft. This paper describes the effort s t o integrate component technologies developed for electro -optical (EO) camera -based aircraft detection system into a SAA capability for High Altitude Long Endurance (HALE) UAVs such as Global Hawk and Predator B . The major technology gap preventing EO m easurements from be ing directly us ed with a collision avoidance system is the lack of range information. In this paper, the authors investigate the feasibility of estimating the range and velocity of other air t raffic by performing a small self -maneuver . The authors explore the performance of ra nge estimation while subject to the ownship maneuverability and other mission and operational constraints such as staying within the assigned Air Tra ffic Control (ATC) corridor . Furthermore, the authors investigat e the effects of range estimat ion errors on the collision avoidance performance .