Bottom estimation and following with the MARES AUV

It is becoming more and more common to use Autonomous Underwater Vehicles to perform tasks underwater. The use of this vehicles is affordable and its use doesn't raise any significant risk nor does it requires any human intervention. The traditional applications for the use of such vehicles were related with bathymetric tasks. But nowadays AUVs are being more and more used for variety of missions in open water environments, including the inspection of underwater structures and environmental monitoring in diverse oceanographic expeditions. Following some previous work, this paper addresses the problem of bottom following by an Autonomous Underwater Vehicle in an environment which is not previously known. In particular, the focus is on integrating a reactive behaviour based on environment sensing, with the on-board navigation software of the MARES AUV. For this, a guidance algorithm will provide the necessary pitch and depth references to the control layer of the vehicle. While the altitude towards the seabed can be measured with an altimeter, the pitch reference values are based on realtime estimation of the slope of the seabed. By doing so, it is possible to control the vehicle in a way that it will always maintain a constant attitude towards the bottom, and the trajectory followed will remain parallel to bottom, regardless of it's profile.