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Toshihiro Maki,Hiroumi Horimoto,Takashi Ishihara,Kazuya Kofuji 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.3
This paper proposes a method for autonomous underwater vehicles to chase sea turtles without attaching any tag to them, toward efficient and long-term observation of marine life. The method uses a multibeam imaging sonar as the main sensor to detect sea turtles. The method utilizes convolutional neural network (CNN) for detecting a sea turtle in sonar imagery. Surge and yaw movements of the vehicle are controlled to maintain the relative distance and direction to the detected target. The proposed method was implemented in the AUV HATTORI. The AUV succeeded in tracking a sea turtle in natural condition for 270 seconds in shallow sea.
Bearing Only Localization for Multiple AUV with Acoustic Broadcast Communication
Kenichi Fujita,Takumi Matsuda,Toshihiro Maki 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
This paper presents the method and characteristic of bearing only localization applying for multiple low-cost autonomous underwater vehicles (AUVs). In the proposed method, each AUV equips sensors which are not always accurate enough to estimate position. The method estimates the positions of the AUVs combining the information of the directions from the AUVs to the acoustic source and sensor values on the AUVs. This paper analyzed the capability of this method using the mathematical model of the system with observability rank condition. The result indicates the system has observability as far as the AUV does not move directly from or to the acoustic source. The position of the AUVs was also estimated using the particle filter. The method succeeded in the particles from diverging. We also observed that the accuracy of the estimation depends on the relative position of the acoustic source from the AUV.
Sakurai, Takeo,Kobayashi, Jun,Kinoshita, Kyoko,Ito, Nozomi,Serizawa, Shigeko,Shiraishi, Hiroaki,Lee, Jeong-Hoon,Horiguchi, Toshihiro,Maki, Hideaki,Mizukawa, Kaoruko,Imaizumi, Yoshitaka,Kawai, Toru,Suz Wiley Periodicals 2013 Environmental toxicology and chemistry Vol.32 No.9
<P>The authors investigated the kinetics of transfer of perfluorooctane sulfonate (PFOS) from water, suspended sediment, and bottom sediment to a marine benthic fish, the marbled flounder (<I>Pseudopleuronectes yokohamae</I>). Fish were exposed in 3 treatments to PFOS in combinations of these exposure media for 28 d and then depurated for 84 d. A major part (37–66%) of PFOS in the fish was in the carcass (i.e., whole body minus muscle and internal organs). Three first-order-kinetic models that differed in exposure media, that is, 1) sum of dissolved and particulate phases and sediment; 2) dissolved phase, particulate phase, and sediment; and 3) dissolved phase only, were fitted to the data assuming common rate constants among the treatments. The uptake efficiency of dissolved PFOS at the respiratory surfaces was estimated to be 3.2% that of oxygen, and the half-life of PFOS in the whole body to be 29 d to 31 d. The better fit of models 1 and 2 and the values of the estimated uptake rate constants suggested that the PFOS in suspended and bottom sediments, in addition to that dissolved in water, contributed to the observed body burden of the fish. Based on an evaluation of several possible contributing factors to the uptake of PFOS from suspended and bottom sediments, the authors propose that further investigation is necessary regarding the mechanisms responsible for the uptake. <I>Environ Toxicol Chem</I> 2013;32:2009–2017. © 2013 The Authors. <I>Environmental Toxicology and Chemistry</I> Published by Wiley Periodicals, Inc., on behalf of SETAC. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.</P>