Observation of breakwaters and their rock mound by AUV "Tri-Dog 1" at Kamaishi Bay

This paper proposes a navigation method for an Autonomous underwater vehicle (AUV) operating around structures whose major configuration given in advance. The method consists of a state estimator and a motion controller, enabling localization in the configuration map as well as following pregiven waypoints without any external help. The state estimator is based on a "particle filter" where the vehicle\´s state, horizontal position and heading, is stochastically updated in real time using multisensor data. This method was implemented on the AUV "Tri-Dog 1" and experiments were carried out around breakwater caissons at the mouth of Kamaishi bay, Iwate Prefecture in Japan. This is the first time a vehicle has succeeded in fully autonomous observation around breakwater caissons. Mosaics of the foot protection blocks, rock mound and caisson\´s surface are made from the observed images based on the estimated state of the AUV, to verify the performance of the method.