Automatic Landing System for UAV by Laser

摘要

An alternative to the landing of UAVs by nets, airbags, parachutes or by steering commands of an external pilote is the landing by an automatic system. The key feature of the system OPATS (Object Position And Tracking Sensor) is the continuous position measurement of the approaching UAV by means of an eyesafe, infrared laser beam which is echoed back from the UAV. The measured position data are continuously transmitted to the ground control station, processed and used to control the UAV on its glide path via the data uplink to the UAV. The landing process is started when the UAV enters a predetermined window in the sky. The laser system scans the window until the laser beam is reflected by the UAV. From that moment onwards the UAV is caged and the positions are continuously measured while the laser beam follows the UAV. This enables to control the UAV on a predetermined landing approach path until the end of the landing phase. The system on ground consists of a Laser Radar on a moveable platform and an Electronic Unit, powered by a rechargeable battery. On the UAV a heatable retroreflector is mounted at the front side of the UAV. The Laser operates in the near infrared spectum. It uses simultaneously two wavelengths in order to improve the penetration through the atmosphere at poor visibility. OPATS is in operation with the Swiss Air Force since four years and some other countries have started to use it. The experiences with more than 500 automatic landings have shown that OPATS is a reliable, precise, easy to operate and cost effective system for UAV autolanding. It was shown that a landing area of 20m x 200m for touch down and full stop is sufficient. The performance was achieved in cold and hot areas, at day and night.