UAV position and attitude estimation using IMU, GNSS and camera

The aim of this paper is to present a method for integration of measurements provided by inertial sensors (gyroscopes and accelerometers), GPS and a video system in order to estimate position and attitude of an UAV (Unmanned Aerial Vehicle). Inertial sensors are widely used for aircraft navigation because they represent a low cost and compact solution, but their measurements suffer of several errors which cause a rapid divergence of position and attitude estimates. To avoid divergence inertial sensors are usually coupled with other systems as for example GNSS (Global Navigation Satellite System). In this paper it is examined the possibility to couple the inertial sensors also with a camera. A camera is generally installed on-board UAVs for surveillance purposes, it presents several advantages with respect to GNSS as for example great accuracy and higher data rate. Moreover, it can be used in urban area or, more in general, where multipath effects can forbid the application of GNSS. A camera, coupled with a video processing system, can provide attitude and position (up to a scale factor), but it has lower data rate than inertial sensors and its measurements have latencies which can prejudice the performances and the effectiveness of the flight control system. The integration of inertial sensors with a camera allows exploiting the better features of both the systems, providing better performances in position and attitude estimation.