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The ocean covers about two-thirds of the earth and has a great effect on the future existence of all human beings. About 37% of the world's population lives within 100 km of the ocean. The ocean is generally overlooked as we focus our attention on land and atmospheric issues; we have not been able to explore the full depths of the ocean and its abundant living and non-living resources. For example, it is estimated that there are about 2,000 billion tons of manganese nodules on the floor of the Pacific Ocean near the Hawaiian Islands. We discovered, by using manned submersibles, that a large amount of carbon dioxide comes from the seafloor and extraordinary groups of organisms live in hydrothermal vent areas. Marine robots including unmanned surface vehicles and unmanned underwater vehicles can help us better understand marine and other environmental issues, protect the ocean resources of the earth from pollution, and efficiently utilize them for human welfare. This paper briefly presents some exemplary models of recent developments in marine robots in different application areas.

In autonomous system, it is important to establish a control scheme that works with stability even near singularity conJigurations. In this article, we describe an on-line trajectory control scheme that uses the manipulability measure as a distance criteria to avoid manipulator singularities.The proposed approach consists in a method for limiting the minimum value of the distance criteria. The pe$ormance is simply affected by the choice of the lower limit. Based on a real-time evaluation of the measure of manipulability, this method does not require a preliminary knowledge of the singular configurations. The proposed algorithm is validated by experimental results.

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