Robust Aerial Docking in Carrier-Centered Frame: A Relative State-Based Approach

Aerial docking of micro uncrewed aerial vehicles (UAVs) onto aerial carrier platforms is significantly affected by various disturbances, particularly in the terminal docking phase. The downwash generated by the micro UAV and gust wind can induce considerable disturbances to the carrier, resulting in position drift that compromises docking success. Conventional disturbance-rejection control on the carrier UAV is often insufficient to effectively suppress various disturbance. To address this challenge, this letter proposes an efficient aerial docking framework entirely formulated in the body-fixed reference frame of the carrier UAV. By modeling the relative dynamics of micro UAVs in the non-inertial carrier-centered frame, we design a docking trajectory planning and tracking control method that relies on relative state measurements without prior knowledge of the carrier UAV's moving trajectory in the world frame. This formulation converts the docking position deviation induced by the drift or unknown motion of the carrier UAV into a docking trajectory tracking error, thereby avoiding frequent trajectory replanning. Real-world results demonstrate that compared with prior works, proposed method achieves accurate docking performance under the carrier's unpredictable motion or drift due to wind gusts.