Session: 04-06-01: Underwater Vehicles and Tools

Submission Number: 157149

Underwater Data Harvesting From a Bottom Landing Observatory Using AUVs With Underwater Optical Wireless Communication 

The Deep-sea development involves seabed disturbance, and the environmental monitoring is an essential issue from pre-development to post-development. The bottom landing observatory (lander) and the AUV are seafloor exploration equipment that can independently conduct surveys on the seafloor, and are often used for deep-sea floor environmental monitoring. Landers are effective for long-term environmental observation of fixed points on the seafloor to obtain continuous temporal changes. AUVs are effective in observing a wide area of the sea-floor and detecting spatial singularities by navigating autonomously. Therefore, it would be possible to optimize the required monitoring system by combining multiple landers and multiple AUVs at the site of deep-sea floor development.

In addition to the above, simultaneous seafloor deployment of the lander and AUVs will also enable underwater data harvesting. Generally, in order to confirm the observation data of a lander, after the lander observes the seafloor, it is necessary to surface it, recovery it by a research vessel, and obtain the observation data accumulated inside the lander. The period of observation by the lander may extend over a year, during which time there is a risk that the lander will fail to record observations, or that the lander will be lost in an accident. On the other hand, in the case of a typical AUV operation, the launching AUV from the research vessel, AUV observation of the seafloor, surfacing, recovery, and obtain the observation data will be completed in one day. Therefore, if the observation data of the lander can be transferred to the AUV during they are simultaneously deployed on the seafloor, it will facilitate the robust environmental monitoring of the seafloor.

In this study, we conducted the sea trials of the seafloor observations and the underwater data harvesting. The lander "EDOKKO Mark-I T2 type", and two AUVs "Horbulin", "Hobalin2" were deployed simultaneously at a depth of 100 m in Suruga Bay, Japan. The AUVs approached the lander and obtained the observation data accumulated on the lander via underwater optical wireless communication, and the observed data were confirmed on board the research vessel. The underwater acoustic communication and positioning devices, SeaTac X150, were used as the equipment for the AUV approach to the lander, and the underwater optical wireless communication devices, MC100, were used as the equipment for the data transfer from the lander to the AUV. Each of the AUV “Horbulin” and “Hobalin2” approached the lander “EDOKKO Mark-I T2 type” within 7 m distance, positioned in front of the lander, established underwater optical wireless communication, and successfully transferred approximately 3 GB of video data stored on the lander. These video data were confirmed on the research vessel prior to the lander being recovered on the research vessel.

In sea trials, multiple AUVs approached the lander individually, transferred the video data accumulated on the lander, and brought them back to the research vessel along with the seafloor data observed by the AUVs themselves. This is important in the sense of the multiple collection routes were secured for the underwater data harvesting.

Presenting Author: Masahiko Sasano National Maritime Research Institute

Presenting Author Biography: 2004 - National Maritime Research Institute
2001 - 2003 Communication Research Laboratory
1999 - 2000 Institute for Cosmic Ray Research, The University of Tokyo
1995 - 1999 Physics, Graduate School, Department of Science, Osaka City University