The underwater platform which has enough ability to cruise globally and freely in vast deep sea will allow us to make the survey of entire oceans. We aim to develop an underwater platform which travels and surveys across entire oceans for the research into the global change, ocean-trench earthquake, and biodiversity and so on. We have developed the first prototype underwater platform or the long-range cruising autonomous underwater vehicle (LCAUV) named Urashima since 1998. The vehicle powered by a polymer electrolyte fuel cell system marked the world record of cruising distance of 317 kilometers in 2005. The vehicle has the following specifications: length; 10 m, weight; 10 tons, maximum depth ratings; 3500 m, maximum cruising speed; 3.2 knots, and endurance; 60 hours. This large vehicle has large user payload of a few hundreds kilograms. In 2007, we started research and development of the elemental technologies which will be utilizes for development of the second generation LCAUV to achieve cruising range of over 3000 kilometers. The technologies under research and development are power sources, navigation methods, communication methods, vehicle controllers, materials for body, and advanced sensors for highly resolution survey. The fuel cell and secondary battery hybrid system is had to improve at energy efficiency to generate electricity as possible for long time running with limited energy. A high accuracy inertial navigation system and an underwater positioning system being covered area of over 1000 km are under development. A synthesized aperture sonar is also under development.
A robust phase gradient bearing estimation algorithm for a tri-axis cross-dipole acoustic array, with application to a long range autonomous underwater vehicle homing and tracking system
