The evolution of electrical and electronic engineering technology including nanotechnology over the last several years has led to improvements in the development of mobile underwater platforms or autonomous underwater vehicles (AUVs) enabling them to go where tethered vehicles or manned vehicles have trouble reaching, such as under the ice, other dangerous zones, and into the deepest depths. In order to survey the whole ocean efficiently, the development of intelligent underwater vehicles will be one necessary solution. For the development of practical intelligent underwater vehicles, designers need cutting-edge fundamental devices incorporated into advanced underwater vehicles. Over the past ten years, the underwater research and development team to which the author belongs has developed five custom-made underwater vehicles: Urashima (Aoki 2001 & 2008), UROV7k (Murashma 2004), MR-X1 (Yoshida 2004), PICASSO, and ABISMO. Urashima is the prototype vehicle of a long cruising range AUV (LCAUV) powered by the hybrid power source of a lithium-ion battery and a fuel cell. Urashima autonomously travelled over 300 km for about 60 hours in 2005. The LCAUV aims to make surveys under the arctic ice possible for distances of over 3000 km. The UROV7k is a tether cable-less ROV, having its power source in its body like an AUV. The UROV7k was designed to dive up to 7000 m without large on-board equipment such as a cable winch, a traction winch or a power generator. The MR-X1 is a middle-size prototype AUV for the test of modern control methods and new hardware and for the development of new mission algorithms. The plankton survey system development project named Plankton Investigatory Collaborating Survey System Operon (PICASSO) project at the Japan Agency for Marine-earth Science and TEChnology (JAMSTEC) aims to establish a multiple vehicle observation system for efficient and innovative research on plankton. By using the ROV Kaiko, which was the deepest diving ROV in the world, a number of novel bacteria were found from mud samples taken in the Challenger Deep in the Mariana Trench (Takai, 1999). However, the lower vehicle of the KAIKO system was lost when the secondary tether was sheared (Watanabe 2004). The most important goal of the ABISMO system is to obtain mud samples from the Challenger Deep in the Mariana Trench, because scientists still want uninterrupted access to the deepest parts of the oceans using a vehicle equipped with sediment samplers. ABISMO consists of a sampling station and a sediment probe. The station contains two types of bottom samplers. One launches the probe to make a preliminary survey, launching the sampler to obtain a sample.
Through the development of these vehicles, many improvements in fundamental devices for underwater vehicles were made. In this chapter, firstly, hardware information on the key devices needed to make cutting edge intelligent underwater vehicles are described. These include new original devices: a small electrical-optical hybrid communication system, an HDTV optical communication system, an inertial navigation system, buoyancy material for the deepest depths, a thin cable with high-tensile strength, a USBL system, a broadcast class HDTV camera system, an HDTV stereoscopic system, a high capacity lithium ion battery, a high efficiency closed-cycle PEM fuel cell, and a prototype of an underwater electromagnetic communication system. In the third section, we present attempts made for data processing methods for autonomous control of underwater vehicles. Finally, the details of the AUVs using the above-mentioned devices are given, including some of the sea trial results.
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