Detailed 3D seafloor imaging of Kagoshima Bay by AUV Tri-TON2

The hovering type AUV Tri-TON 2 was developed by the Institute of Industrial Science, the University of Tokyo in 2013. The AUV was constructed as a test bed for a national project to develop instruments to estimate ore reserves in underwater hydrothermal deposits. The mission of the AUV is seafloor 3D imaging of hydrothermal vent fields. Specifically, the AUV has two wets of imaging instruments: one looking forward and one looking down. The imaging instrument consists of a camera, a sheet laser for light section ranging system, and a flash. In order to estimate its position and orientation in real time, the AUV uses a SBL-based acoustic localization device instead of a conventional inertial navigation system. The AUV estimates its position by mutual acoustic positioning with a seafloor station. In addition, the AUV uses a Doppler velocity log and a fiber optic gyro for dead reckoning. The performance of the AUV was verified through a series of tank and sea experiments. In this paper, the results of seafloor observation by Tri-TON 2 in Uchiura Bay and Kagoshima Bay are described. During the experiment at Uchiura Bay, performance of the self-position estimation was verified. Afterwards, the AUV succeeded in imaging tubeworm colonies in Kagoshima Bay.