Aerial Landing of Micro UAVs on Moving Platforms Considering Aerodynamic Interference

Despite numerous studies of landing on moving ground platforms, landing on midair aerial platforms remains a significant challenge due to aerodynamic interference between Unmanned Aerial Vehicles (UAVs). This letter presents a systematic onboard and real-time trajectory optimization solution for the UAV landing on its midair carrier platform. With numerical calculation, the aerodynamic interference between the micro UAV and its carrier UAV is estimated. Based on the estimation result, we construct a no-fly zone around the carrier UAV to minimize the aerodynamic disturbances. A guided landing cone above the carrier is modeled to guide the micro UAV landing on the carrier. Such a design can minimize the carrier UAV position drift induced by the micro UAV's down-wash flow, ensuring flight safety and response speed constraints simultaneously. The agile and accurate landing trajectory of the micro UAV landing on either hovering or moving carrier UAV is planned by spatial-temporal joint trajectory optimization. The proposed systematic method is validated in both simulation and experimental tests. As a result, the proposed planner can generate optimal trajectories under both hovering and moving conditions of the carrier UAV in about 50 ms with a precision of around 10 cm.