Tracking Control for Free-Space Optical Communication of Unmanned Aerial Vehicle

The acquisition and tracking control strategy is addressed in this study for FSO (Free-Space Optical) communication between GCS (Ground Control Station) and UAV (Unmanned Aerial Vehicle) such as a drone. In comparison with the FSO communication system for a satellite, the UAV FSO system requires precise tracking control to cope with the fast changing rate of directional angle due to its short relative distance. Two modes of the control strategies are presented in this study: 1) From an initial state, GCS optical laser module is driven by PTU (Pan Tilt Unit) to acquire LOS (Line Of Sight) between the GCS and the UAV and 2) the optical module on the UAV is finely controlled to coincide its direction with the direction of GCS optical module. By using the computer simulation, the output value of the optical sensor is obtained in accordance with the incidence angle and the position of Gaussian laser beam onto the optical sensor. Based on the results of simulation, experiments are carried out to verify the proposed control strategies in this study.