Autonomous Recovery of a Fixed-Wing UAV Using a Line Suspended Between Two Multirotor UAVs

This article presents an autonomous recovery system for fixed wing unmanned aerial vehicles (UAVs) which is using a line suspended between two multirotor UAVs to catch a line with a hook hanging from a fixed-wing UAV. This method of recovery is particularly suitable for recovery in space constrained areas such as on small ships. A control system is presented for the proposed recovery concept and the concept is validated through experiments. The results include 17 test runs to characterize control accuracy, followed by three successful recoveries. With the selected equipment and tuning values, the multirotors were able to track the fixed-wing UAV with a mean error of 0.8 m at the moment the catch would have happened in the 17 test runs. The margins for missing for the three recoveries were 1.0-2.1 m showing that this recovery method is robust.