“…Considering the UAV type, the focus of most of the studies was divided between fixed-wing UAVs and multirotor vehicles. Within the latter sub-category, fourteen papers explicitly referred to quadrotor systems [16,24,31,32,34,35,43,44,50,79,83,90,105,106], two to hexarotor UAVs [64,133], one to bicopters [85] and one to octocopter drones [108], respectively. Several papers did not specifically state a UAV type target in terms of architecture configuration, whereas others focused more properly on the drone characteristics, as the specific performance that the UAV needed to assure, or the kind of mission in which the system was expected to be engaged [36,[40][41][42].…”