Vision based attitude and altitude estimation for UAVs in dark environments

This paper presents a system dedicated to the real-time estimation of attitude and altitude for unmanned aerial vehicles (UAV) under low light and dark environment. This system consists in a fisheye camera, which allows to cover a large field of view (FOV), and a laser circle projector mounted on a fixed baseline. The approach, close to structured light systems, uses the geometrical information obtained by the projection of the laser circle onto the ground plane and perceived by the camera. We present a theoretical study of the system in which the camera is modelled as a sphere and show that the estimation of a conic on this sphere allows to obtain the attitude and the altitude of the robot. We propose some experiments based on simulated data and real sequences. The estimated attitude and altitude from our method are comparable with commercial sensors in terms of its accuracy and correctness. The results also prove its suitability for autonomous take-off and landing as well as for the case of low altitude manoeuvre in dark environments. It also provides room for additional payload to be used for different applications due to use of light weight micro-camera and laser system.