Towed-body trajectory tracking in aerial recovery of micro air vehicle in the presence of wind

This paper presents a method for recovering Micro Air Vehicles (MAVs) in flight using a mothership and towed drogue, in which the mothership executes an orbit that places the drogue in a stable, slower orbit that can be tracked by a MAV. This paper is particularly challenging in the presence of wind. The equations of motion of the cable using an elastic model are presented. Based on the differential flatness of the system with the knowledge of the wind, the desired mothership trajectory can be calculated from the desired drogue orbit. A Lyapunov-based controller derived using backstepping is proposed that enables tracking error of mothership to exponentially converge to an ultimate bound, where the size of the ultimate bound is a function of the unknown portion of the wind. Simulation results verify the feasibility of the approach.