Radio direction finding for maritime search and rescue

Two unmanned aerial vehicles (UAVs) are required to respond to a maritime emergency beacon, localise it, and then circle around it in an optimal configuration. Each UAV is able to measure bearing to the beacon but not its range. Novel guidance and control strategies based on cost function gradient search techniques are developed to achieve a continuous reduction in the estimate of the beacon location. Simulation studies reveal the localisation and circling behaviour achieved with the various cost functions, and a new minimum estimation error configuration is discovered. A direct cost function based on an ´area-of-uncertainty´ metric achieved the best localisation considering flight and localisation time.