An advanced sense and collision avoidance strategy for unmanned aerial vehicles in landing phase

Unmanned Aerial Vehicles (UAVs) become promising in different civilian and military applications due to their lower cost and greater flexibility in comparison to manned aircraft. However, the growing diversity of flight makes UAVs vulnerable to mid-air collisions. To ensure the safety for manned aircraft, human pilots are responsible for detecting intruders in airspace and performing appropriate maneuvers to avoid collisions. Unlike manned aircraft with human pilots involved, UAVs must be equipped with Sense and Avoid (SAA) systems to guarantee the flight safety. Thus, SAA systems play an important role in merging UAVs into the National Airspace System. As illustrated, an SAA scheme is composed of four units, which are sensing, conflict detection, collision avoidance, and flight controller, respectively.