The landing problem of a VTOL Unmanned Aerial Vehicle on a moving platform using optical flow

This paper presents a nonlinear controller for hovering flight and landing control on a moving platform for a Vertical Take-off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) by exploiting the measurement of the average optical flow. The VTOL vehicle is assumed to be equipped with a minimum sensor suite (a camera and an IMU), manoeuvring over a textured flat target plane. Two different tasks are considered in this paper: the first one concerns the stability of hovering flight and the second one concerns regulation of automatic vertical landing on a moving platform using the divergent optical flow as feedback information. Simulation and experimental results performed on a quad-rotor UAV demonstrate the performance of the proposed control strategy.