Civil engineers of the hydroelectric companies, carry out periodic visual inspections of the state of the concrete. Commonly this is achieved through a careful visualization of a video recorded by a professional diver or a ROV. Our approach to this problem consist on the use of an AUV which follows a pre-programmed path facing the wall while snapping images. A localisation system based on a moored buoy equipped with a DGPS receiver, an USBL transceiver and a MRU is used to georeference the AUV position. Onboard, a navigation system based on a DVL and a MRU-FOG is used for the AUV navigation.  After the mission, the set of gathered images together with the localisation data obtained in the buoy are combined and used to setup an image mosaic of the wall of the dam using an image mosaicking system which has been also developed in our lab.

During February 2009 the final experiments about Visual Dam inspection took place in the Pasteral Dam in Girona (Spain). During the experiment the ICTINEU-AUV followed a survey trajectory while keeping a relative pose (heading and distance) with respect to the wall. Using artificial illumination and a forward looking the camera the robot grabbed images along the trajectory. For real time navigation the robot relied exclusively on DVL-FOG navigation while a USBL-DGPS-MRU system mounted on a floating buoy was used for robot tracking as well as for geo-referencing the images through post-processing. Finally a geo-referenced image mosaic of the dam wall was setup.