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UNDERSEA EXPLORATION:
Next-Generation Robot Developed
NOVEMBER 22, 1996
New Exhaust-Free Design
A next-generation undersea exploratory robot, able to dive as deep as 400 meters and operate on its own power for as long as 24 hours, has made its appearance. Developed jointly by the University of Tokyo's Institute of Industrial Science and a private shipbuilding firm, the robot is propelled by a diesel engine. It is said to be the first free-operating undersea exploratory robot not to run on batteries. Compared to scientific investigations carried out from the surface of the ocean, those using this robot will be able to detect changes in the ocean with greatly increased precision.
The cylindrical robot measures 8.3 meters in length and 1.2 meters
in width, and reaches a top speed of 3.6 knots. Its main feature is
the newly designed propulsion system, a motor powered by electricity
generated by the robot's diesel engine. The engine itself is a completely
closed system that needs no intake of air to run and chemically processes
exhaust gas inside the robot. On-board devices reinfuse the exhaust
with oxygen after removing its carbon dioxide and reuse the gas in
the fuel mixture. The seawater is kept clean, as no gas is released.
Instruments aboard the robot take quick measurements of the seawater's oxygen content, salinity, temperature, and pH value at four-second intervals, or about every five meters. The robot can also be equipped with instruments to measure magnetic fields and metal concentrations in the water, and otherwise investigate the oceanic environment.
There are around 20 non-tethered undersea exploratory robots in the
world, but they are of limited utility as they all run on expensive
silver-zinc power cells that can be recharged no more than 50 times
or so before they become useless. The newly developed robot, on the
other hand, runs on a modified diesel engine, which both decreases
the cost of operation and increases the useful lifetime of the machine.
Japan's Successful Deep-Sea Exploration Program
In the field of Japanese oceanography, deep-sea expeditions are regarded as especially advanced. In March 1995, the Marine Science and Technology Center, affiliated with the Science and Technology Agency, sent its "Kaiko" unmanned deep-sea probe to a depth of 10,911 meters in the Mariana Trench, off the coast of Guam. And in August 1989, the manned probe "Shinkai 6500" successfully reached a depth of 6,527 meters. These are the deepest-operating manned and unmanned probes currently in commission.
Both of these probes are equipped to obtain specimens of rock and
detritus from the sea floor, and can thus increase our understanding
of ancient geology and deep-sea biology. Both probes, however, require
from two-and-a-half to three hours to reach their operating depths.
Furthermore, the "Kaiko" probe is connected to a surface ship via
a communications cable, and the "Shinkai 6500" has a limited time
that it can stay underwater. Neither, therefore, is appropriate for
extended oceanographic surveys, both having an operating radius of
only 200 meters or so. The newly designed robot is expected to be
able to perform farther-ranging survey activities in shallower depths.
Copyright (c) 2001 Japan
Information Network. Edited by Japan Echo Inc. based on domestic Japanese
news sources. Articles presented here are offered for reference purposes
and do not necessarily represent the policy or views of the Japanese
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(Photos: Mitsui Engineering and Shipbuilding Co.)

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