Evaluation of position estimation of AUV Tri-TON 2 in real sea experiments

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. 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. In our proposed method, the measurements from the acoustic localization device, DVL and FOG are fed into a particle filter algorithm for position estimation. The validity of the position estimation method with Tri-TON 2 was evaluated in Uchiura Bay, Japan in August 2014 at depth of 35 m. In this paper, the results of the experiments are described in detail. The estimated positions were evaluated by comparing the ground truth obtained by a high-accuracy pre-calibrated global acoustic positioning system.