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Morito, Makoto*; Fujii, Shun*; Yoshimura, Koki*; Sanada, Yukihisa; Baba, Shoichiro*; Matsunaga, Hiroshi*; Mori, Takami*; Sato, Keiichiro*; Tahara, Junichiro*
Proceedings of 34th International Ocean and Polar Engineering Conference (ISOPE-2024), p.3754 - 3761, 2024/06
This study proposes a method that combines sliding mode control and neural networks as a control method for unmanned surface vehicle to measure radiation in submarine soil. Sliding mode control is used as the base of control input, and corrective inputs are added using a neural network controller so that one of the parameters of sliding mode control, 
, and its rate of change are reduced. After producing a control system using this method, we conducted simulation tests and sea area tests to evaluate whether the survey could be conducted using this method.
Kato, Tetsu*; Kawamura, Yamato*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa; Fujii, Shun*
International Journal of Offshore and Polar Engineering, 31(3), p.316 - 324, 2021/09
Times Cited Count：2 Percentile：13.00(Engineering, Civil)The development of a side thruster system (vehicle (ASV)) that can maintain the direction of travel on the autonomous surface will be explained. Currently, we are working on a mud radioactivity survey in collaboration with Japan Agency for Marine-Earth Science and Technology, Japan Atomic Energy Agency, and Tokyo University of Marine Science and Technology. Deposited at the mouth of Fukushima Prefecture, Japan, the main purpose is to collect unmanned mud using ASV. The Mad Collection has developed a side thruster system and implemented it in ASV. We have confirmed the operation of the ASV with the joystick by using the thruster system for operating the ASV by one person using the joystick.
Sanada, Yukihisa; Miyamoto, Kenji*; Momma, Hiroyasu*; Miyazaki, Nobuyuki*; Nakasone, Takamasa*; Tahara, Junichiro*; Baba, Shoichiro*; Furuyama, Hiroki*
Marine Technology Society Journal, 55(5), p.222 - 230, 2021/09
Large quantities of volatile radionuclides were released into the atmosphere following the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in March 2011. To evaluate their effect on aquatic organisms and radiocesium behavior in the environment, the monitoring of radioactive cesium in the waterbed soil is important. We developed a dedicated radiation survey device that can both directly measure and collect some sediment samples. A comprehensive test was conducted using this device, which was installed in an unmanned surface vehicle at Fukushima offshore contaminated by radiocesium that resulted from the FDNPS accident. Consequently, the effectiveness of this device was confirmed because the measurement results of the sediment-core sample and in-situ radiation survey results show a good correlation. A successful application of this device in the time of post-nuclear facility accident is expected.
Fujii, Shun*; Kato, Tetsu*; Kawamura, Yamato*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
Proceedings of 26th International Symposium on Artificial Life and Robotics (AROB 26th 2021), p.280 - 285, 2021/01
In recent years, autonomously navigating unmanned vessels have been actively studied, and many of these vessels are designed to perform unmanned operations such as observation and transportation. On the other hand, this study uses an unmanned ship with a moon pool that collects seabed mud, which is difficult for ordinary ships. Vessels used since the area are highly turbulent due to wind, so it is necessary to maintain a fixed point and orientation when removing mud. The ship is equipped with side thrusters to maintain a fixed point and bow direction. In this study, the control method was devised to maintain fixed point and orientation, and the control method is based on robust sliding mode control. The proposed control method was verified by simulation, and the desired behavior was confirmed.
Kato, Tetsu*; Kawamura, Yamato*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
Proceedings of the 30th (2020) International Ocean and Polar Engineering Conference (ISOPE 2020) (USB Flash Drive), p.1255 - 1260, 2020/10
眞田 幸尚
田原 淳一郎*; 藤井 竣*; 馬場尚一郎*
JP, 2023-179160 
Patent licensing information
【課題】外乱が大きい場合であっても、海洋ロボットの位置を精度よく保持すること。 【解決手段】第1の推進器および第2の推進器を有する推進機構を備える海洋ロボットを制御する制御装置であって、海洋ロボットの目標位置および現在位置を含む位置情報を取得する情報取得部と、位置情報に基づいて切換関数を生成し、海洋ロボットの現在位置が目標位置に一致するようにスライディングモード制御を行うためのスライディングモード制御値を生成するスライディングモード制御部と、位置情報および切換関数に基づいて、海洋ロボットの現在位置が目標位置に一致するようにニューラルネットワーク制御を行うためのニューラルネットワーク制御値を生成するニューラルネットワーク制御部と、スライディングモード制御値およびニューラルネットワーク制御値に基づいて推進機構に入力される制御入力を生成する制御入力生成部とを備える。
Morito, Makoto*; Yoshimura, Koki*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
no journal, ,
We study control systems for an Unmanned Surface Vehicle for mud extraction. Mud sampling USV is equipped with a mud sampler, which is lowered to the seabed by a winch for sampling and surveying. During mud sampling surveys, the cable between the hull and the mud sampler should be slackened so that the mud sampler and the hull do not influence each other through the cable. Strong winds blow in the area to be surveyed during the winter months and many momentary gusts are observed. This requires strong position and angle control (Dynamic Positioning) to prevent wind effects for the USV to extract mud. The USV has main thrusters for forward and backward travel and bow thrusters/stern thrusters for left-right travel and turning. During mud extraction, the main thrusters are used to move the vessel forward and backward, and the bow and stern thrusters are used to move left and right to maintain the position of the hull in which the mud extraction is carried out. During DP (Dynamic Positioning), the bow thruster and stern thruster are used to hold the bow heading of the USV constant, preventing the twisting of the cable connecting the USV to the mud sampler. Therefore, when the USV performs DP, it is necessary to properly perform three controls: Surge control, Sway control, and Yaw control. At this time, both Sway and Yaw control of the USV using bow and stern thrusters.
Yoshimura, Koki*; Morito, Makoto*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
no journal, ,
We are researching and developing an unmanned surface vehicle (USV) to measure radiation contained in mud on the seafloor in the waters off Fukushima Prefecture. This is the area where radiation was released due to the accident at the Fukushima Daiichi Nuclear Power Station. We decided to use a USV to collect mud in this area. The USV was developed by JAMSTEC and has an overall length of 6 meters, an airborne weight of 4 tons, and a maximum speed of 4 knots. The hull has a moon pool from which a winch is used to lower the mud sampling equipment to the seafloor for mud sampling. In a previous study, a position maintaining control of this USV was realized by combining sliding mode control and corrective input by a neural network, and tested in actual environment. On the other hand, there is a problem that the condition of the seafloor in the survey area cannot be grasped for mud sampling in the real environment. This may cause the mud sampler to fall over if there is an obstacle or slope on the seafloor at the survey point. In addition, because the soil quality of the seafloor cannot be confirmed prior to mud sampling, it is not possible to efficiently collect data on different soil qualities. Therefore, seafloor mapping operations of the survey area using side scan sonar are necessary.
Fujii, Shun*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
no journal, ,
Yoshimura, Koki*; Fujii, Shun*; Morito, Makoto*; Sato, Tasuku*; Tahara, Junichiro*; Baba, Shoichiro*; Sanada, Yukihisa
no journal, ,
no abstracts in English
