Development of Precision Underwater Positioning System

The Shimonoseki Research and Engineering Office for Port and Airport, Kyushu Regional Development Bureau, Ministry of Land, Infrastructure and Transport in cooperation with the Oki Electric Co. Ltd, has developed the advanced underwater positioning system. A measurement of position x, y and z of underwater structure is needed to settle the structure in water, and to manage the construction in port area. A quality inspection of structures at port such as pier by the Remote of Vehicle (ROV) is also needed to grasp its exact 3 dimensional position in water for manipulating it. Presently, the above mentioned underwater measurement work, particularly required high accuracy, is needed many workers, surveyors work on land for measuring the scale of underwater-staff and divers work in water for supporting the underwater-staff, and is met highly risks of incident. Especially, in case of the offshore working, longer distance from land and deeper depth of water are cause of difficulty of its implementation. To cope with these issues, we have developed the system and have verified its effectiveness by demonstration on the sea. The system consists of 2 measurement technologies, the Global Positioning System (GPS) is utilized measuring on water and supersonic wave with ROV is for probing under water. Using the system can be readily available to high accuracy measurement without divers, even offshore working. This paper presents outline of the system and the result of the demonstration.