Broadcast transponders for low flying unmanned aerial vehicles

Present day unmanned aerial vehicle (UAV) technology in urban mobility applications is severely limited in use due to lack of reliable collision avoidance mechanisms. There are numerous applications for UAVs in urban environments, including information awareness, urban management, on-demand goods deliveries, and even parking assist, but present day legal regulations preclude their use over safety concerns, requiring presence of a pilot and restricting UAV use in urban areas. Indeed, possibility of midair collision is a significant concern in a densely populated urban area, and will only get worse as UAV use becomes widespread. Collision avoidance cannot be done effectively using onboard sensors. A transponder system like automatic dependent surveillancebroadcast (ADS-B) could be used to augment airspace awareness of UAVs, greatly reducing collision risks. SPH Engineering has successfully integrated such transponders with two of the most popular consumer class autopilots. In each case a device by Sagetech was used, the smallest commercially available transponder to date. This is a major step towards commercial UAV integration into regulated airspace. Unfortunately, ADS-B is ill suited for small low flying UAVs that are navigating unregulated airspace. While weight and power are the more obvious limitations, the use of ADS-B also requires International Civil Aviation Organization (ICAO) certification, which is both expensive and lengthy. Furthermore, at close range receiver was overwhelmed by transmit power. In a collision avoidance scenario for delivery drones short range is exactly where reliable reception is most needed. This article presents an approach, which is used to design a collision avoidance system in accordance with safety regulations of manned aviation that would be specific to small, commercial UAVs operating in unregulated airspace. (C) 2017 The Authors. Published by Elsevier B.V.