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Spiral landing guidance law design for unmanned aerial vehicle net-recovery

Abstract A spiral landing guidance law is proposed for a net-recovery landing of a fixed-wing unmanned aerial vehicle (UAV). In this study, the net-recovery landing is divided into two phases: a spiral descent phase and a final approach phase. In the spiral descent phase, a spiral descending path is designed from any initial position to a final approaching waypoint. The flight path angle of the UAV is controlled to align with the approaching direction at the end of the spiral descent. In the final approach phase, the aircraft is directly guided from the approaching waypoint to the recovery net by a pseudo pursuit guidance law. Sequential imaginary landing and approaching points are generated using a cubic polynomial in the pseudo pursuit guidance law. Therefore, the UAV at a high altitude with an arbitrary heading angle spirals down towards the recovery net without loitering and flies into the recovery net along a desired approaching path. Six-degree-of-freedom numerical simulation is performed to verify the performance of the spiral descent and final approach guidance laws.