Pinpoint Underwater Grab Bucket Navigation System (Pugnavi) Applied to Restoration Work of Great East Japan Earthquake
Type:
Presented during:
WODCON XX: "The Art of Dredging" - 2013, Brussels, Belgium
Authors:
Fujiyama E
Abstract: The Great Eastern Japan Earthquake occurred off the coast along the Tohoku District in the Pacific Ocean on March 11, 2011. The coastal areas in the Tohoku and Kanto districts suffered devastating damage by the Tsunami caused by the earthquake. Immediately after the disaster, in order to reopen main ports in the affected areas, work started on echo-sounding for the purpose of removing obstacles sunk on the seabed
Of particularly concern for the removal of obstacles from the bottom in deep water was the strong current that moves a grab bucket away from the target object. Therefore, we developed the Pinpoint Underwater Grab Bucket Navigation System (PUGNAVI) that guides the grab bucket to a target object accurately. The system consists of the underwater positioning device, GPS, and wireless local area network (LAN). Underwater positioning equipment (transducer and transponder) adopted for PUGNAVI has generally been used for controlling of remotely operated vehicles (ROV). However, there was worry about the adoption of this type of equipment where there was no experience in relation to its use on work vessels. Repetitive field tests have proved that PUGNAVI could accurately achieve realtime positioning of the grab bucket under the condition of strong tidal currents in comparatively deep water.
This report describes the outline of PUGNAVI and how it was applied to restoration work after the Great Eastern Japan Earthquake disaster
Keywords: Earthquake restoration, Underwater positioning system, Position guidance, High accuracy