Wireless Local Positioning System for Controlled UAV Landing in GNSS-Denied Environment

A novel concept for ad-hoc landing of unmanned aerial vehicles (UAV) in GNSS-denied environment is presented in this paper. In our concept at the beginning of the landing phase the UAV drops several active beacons down to the landing site. It enables the UAV to localize itself via distance and angle information to the deployed beacons. The presented wireless local positioning system is based on 24 GHz secondary radar sensors and allows for accurate and robust 3D-positioning even in harsh weather conditions. The specially designed antennas with large angular coverage assure UAV localization disregarding the beacon's position and orientation. The developed beacon design has small size, low weight and power consumption that perfectly suits the application goal. Measurements of localization and landing scenario using four beacons and the radar unit installed on the drone are shown. The 3D-positioning of the UAV with the RMSE under 36 cm using only a single beacon and 31 cm using four beacons were achieved. These results verify the application of the proposed system as an accurate and redundant UAV landing solution.