The ONERA ReSSAC Unmanned Autonomous Helicopter: Visual Air-To-Ground Target Tracking in an Urban Environment

This paper outlines an autonomous flight system developed onboard the ONERA ReSSAC unmanned helicopter for an air-to-ground target tracking mission in an unkown urban environment. The system consists of the following three components: i) an image processor which detects the target and estimates ground motion around the detected target position, ii) an integrated vision/inertial navigation filter which simultaneously localizes the target and the own-ship UAV with an occasional loss of GPS, and iii) a guidance law which achieves target tracking as well as obstacle avoidance. Those algorithms are implemented in the Orocos robotic architecture, integrated with the auto-pilot system of the ReSSAC helicopter, and tested in closed-loop flight of vision-based target tracking.