Towards sonar based perception and modelling for unmanned untethered underwater vehicles

Experimental results obtained with the authors´ calibrated computer-controlled, frequency-modulated subbottom penetrating sonar are presented. A topographic model of the sea-floor surface and a sequence of sonar images, obtained with the same FM sonar, is given. This latter sequence shows a vertical section through the sea-bed itself. Despite the absence of surface features, the variations in stratigraphy of this vertical section and the automation of the interpretation of these features open the possibility of using these data to navigate when resurfacing is either not an option or undesirable