Language：Japanese   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (scientific journal)  

A research project to develop observation systems for heat, momentum, and material circulation in the ocean and atmosphere was carried out by the Research Institute for Applied Mechanics, Kyushu University, from 1992 to 1997, A pitch, roll, and depth controllable towed vehicle called "Flying Fish" was developed which houses an acoustic Doppler current profiler, CO2 analyzer, and sensors for measuring temperature, salinity, dissolved oxygen, pH, turbidity, and chlorophyll. The length of the vehicle is 3.84 m, the breadth is 2.26 m, the height is 1.4 m, the weight in air is 1400 kg, and the weight in water is roughly 0 kg.
Flying Fish enables us to obtain space-continuous data of physical and chemical properties efficiently in the upper mixed layer of the ocean. From 1994 to 1997, the vehicle was used for observations in the northern, southern, and central parts of the Japan Sea in a collaborative study by Japan, Korea, and Russia. Examples of data obtained are shown in this paper and the results of current velocities are compared with those taken by other observation systems.

DOI： 10.1109/48.820745

Language：Japanese   Publisher：The Japan Society of Naval Architects and Ocean Engineers  

DOI： 10.14856/conf.36.0_123

CiNii Research

Language：Japanese   Publisher：The Japan Society of Naval Architects and Ocean Engineers  

DOI： 10.14856/conf.36.0_237

CiNii Research

Language：English   Publishing type：Research paper (international conference proceedings)  

The authors propose a towed vehicle with intentional instability for use in seafloor exploration. This towed vehicle has one pair of canard wings in addition to conventional main and tail wings. The hydrodynamic characteristics and the motion control performance of the multi-winged towed vehicle with the three control surfaces are investigated. First, CFD and experiments were conducted to investigate the effects of interference between the wings. Then, equations of the motion for the multi-winged towed vehicle were formulated and the simulations of the motion control were conducted. The calculations were performed for the longitudinal motion of the vehicle. Since this system has three control inputs (three wing angles) for two control outputs (pitch and heave), the control input to reach the target is not uniquely determined. For this reason, the authors reduced the number of control inputs by linking the angles of the tail and the canard wings at a certain ratio. The motion control simulations confirmed that the pitch and heave can be controlled almost independently, demonstrating the superiority of the multi-winged towed vehicle over conventional ones.

Repository Public URL： https://hdl.handle.net/2324/7173451

Language：Japanese   Publishing type：Research paper (other academic)  

水面下の遺跡や沈没船を発掘，保存，調査する水中考古学分野では，全世界の海域で宮殿や沈没船の発掘が行 われている.一方で，その歴史は比較的浅く海底には歴 史的，学術・技術的に価値を有する船舟類に関する遺跡 が数多く未調査のまま残されている.
前報では長崎県松浦市の鷹島神崎遺跡を対象として， 比較的浅い海域の海底遺跡探査を対象とした小型曳航体 を計画し，その運動制御性能を調査した.沈没船の調査 において遺物の位置が特定された後，多数の画像データ に基づくフォトグラメトリ等の方法により遺物の相対位 置等が詳細に記録される.本報告では発見された遺物の 記録に有索式 AUV を利用する手法について調査する.すなわち，海底の沈没船の記録調査を想定した有索式 AUV を計画し，その運動モデルを構築する.また，得られた 運動モデルに基づく運動制御系の設計と海底遺物の記録 作業のシミュレーションをもとに，有索式 AUV による記 録作業の効率について検討する.

Repository Public URL： https://hdl.handle.net/2324/7178731

Language：Japanese   Publishing type：Research paper (other academic)  

海底の状態を詳細に観察しようとするとき，水中ビークルに搭載した光学カメラを用いて静止画や動画を撮影 することが有用である.海中では光の減衰や散乱の影響 によって可視距離が数メートル程度に限定される場合が 多く，太陽光が届かない水深においては照明を使用して 撮影するため，特にマリンスノーによる後方散乱による 影響が強く，可視距離が短くなる.したがって，海底を 広範囲に撮影するためには，海底の起伏や勾配に追従し， 障害物を回避しながら海底との距離を近く保ったまま水 中ビークルを高速で移動させることができる高い運動性 能が求められる.
本報告では，光学カメラによって海底を撮影する水中 曳航体の運動制御について調査し，その課題を検討する.

Repository Public URL： https://hdl.handle.net/2324/7178730

Language：English   Publisher：International Society of Offshore and Polar Engineers (ISOPE)  

Many archaeological relics such as a wreck of an ancient ship are remains under the sea bottom and most of them are untouched because of difficulties of underwater exploration. Usual sub-bottom explorations for offshore resources such as oil and gas are carried out using seismic and sonic prospecting instruments and it is high cost and time consuming. On the other hand, archaeological relics in the relatively shallow water are explored by a sub-bottom profiler and by divers so the area which can be investigated is very limited. / The authors have been developing underwater towed vehicles and autonomous underwater gliders in the previous studies. These vehicles equip various types of instruments including an OBEM (Ocean Bottom Electro-Magnetometer). They are promising instruments for marine environment survey and ocean floor resources exploration. / In this report, a towed exploration system for archaeological relics exploration is proposed and the development of the vehicle including a motion controller is discussed. The vehicle is towed near the sea bottom to improve the accuracy of the measurement using a sonic prospector. The performance of the towed system and its motion control system are assessed by tank experiments and numerical simulations.

CiNii Research

Language：English   Publishing type：Research paper (international conference proceedings)  

Many archaeological relics such as a wreck of an ancient ship are remains under the sea bottom and most of them are untouched because of difficulties of underwater exploration. Usual sub-bottom explorations for offshore resources such as oil and gas are carried out using seismic and sonic prospecting instruments and it is high cost and time consuming. On the other hand, archaeological relics in the relatively shallow water are explored by a sub-bottom profiler and by divers so the area which can be investigated is very limited.
The authors have been developing underwater towed vehicles and autonomous underwater gliders in the previous studies. These vehicles equip various types of instruments including an OBEM (Ocean Bottom Electro-Magnetometer). They are promising instruments for marine environment survey and ocean floor resources exploration.
In this report, a towed exploration system for archaeological relics exploration is proposed and the development of the vehicle including a motion controller is discussed. The vehicle is towed near the sea bottom to improve the accuracy of the measurement using a sonic prospector. The performance of the towed system and its motion control system are assessed by tank experiments and numerical simulations.

Repository Public URL： https://hdl.handle.net/2324/7178729

Language：Japanese   Publisher：The Japan Society of Naval Architects and Ocean Engineers  

DOI： 10.14856/conf.34.0_103

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)  

水中考古学は水面下の遺跡や沈没船を発掘，保存，調査する研究分野であり，全世界の海域で宮殿や沈没船の発掘が行われているが，その歴史は比較的浅く，海底には歴史的，学術・技術的に価値を有する船舟類に関する遺跡が数多く未調査のまま残されていると考えられる。
本報告では，水中考古学における従来の探査手法について調査し，その課題を検討する。また，鷹島神崎遺跡の元寇沈船探査のため，浅海域を対象とする音波探査と曳航体を組み合わせた探査システムを計画し，試作機の流体力学的特性，運動制御性能について検討する。

Repository Public URL： https://hdl.handle.net/2324/7178732

Language：English   Publishing type：Research paper (international conference proceedings)  

The authors have been developing an autonomous underwater glider which equips an OBEM (Ocean Bottom Electro-Magnetometer). That is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The motion control system for landing of the vehicle was investigated in the previous studies. In these reports, hydrodynamic performance of the vehicle in landing is examined by CFD calculations. The bottom effect which affects the lift and drag of the wings of the glider is studied and the characteristics of the blended wing body near a sea bottom is discussed.
On the other hand, the transient motions of the vehicle such as a deployment, the motion when the vehicle changes its buoyancy for cruise are also important problems for the motion control of the vehicle. The control system might be affected by the unpredicted change of the hydrodynamic forces acting on the body and the wing in the transient conditions. Consequently, it may cause deterioration of the performance of the control system.
In this report, these transient motions are investigated based on CFD analysis. The overset mesh approach is used to simulated the sequential maneuvers in the cruising of the underwater vehicle.

Language：English   Publishing type：Research paper (international conference proceedings)  

The authors have been developing an autonomous underwater glider which equips an OBEM (Ocean Bottom Electromagnetometer). That is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The buoyancy and attitude control mechanism of the vehicle enable to move to the next measurement point by gliding.
The vehicle which has a blended wing body measures the slight variation of electromagnet wave on the sea bottom and the landing point for the measurement must be precisely controlled by the motion control system. In the landing stage, it is predicted that surface effect of the sea bottom affects the hydrodynamic characteristics of the vehicle, and it might cause some problems on the motion control system of the vehicle.
The authors attempt to make clear the characteristics of the flow field around the vehicle in the vicinity of a sea bottom. The motion control system for landing of the vehicle was investigated in the previous study (Yamaguchi and Sumoto, 2019). In this report, hydrodynamic performance of the vehicle in landing is examined by CFD calculations. The surface effect by a sea bottom which affects the lift and drag of the wings of the glider is studied and the characteristics of the blended wing body near a sea bottom is discussed.

Language：English   Publishing type：Research paper (international conference proceedings)  

The Dynamic Positioned (DP) Jack-up vessels currently use two popular designs of legs, (i.e. rack & chord lattices and cylindrical leg type). These two leg designs are popular and various experiment conducted in the past to evaluate the drag coefficient and drag force of these legs, but they are only available in a steady state condition. The intention of our experiment is to measure drag force and compare with CFD results. In DP vessels, mathematical model of the vessel first estimates the environmental force acting on the vessel, by using real time sensor data and then generate the counter balance thrust. The output command of force and angle is then sent to the available thrusters. However, usually, DP Jack-up vessels do not have sensor to measure the hydrodynamic force of leg &spudcan. Presently, each DP control system manufacturer for Jack-up vessels uses its own mathematical technique to achieve stability of station keeping during simultaneous operation of dynamic positioning and Jacking operation (SIMOPS). Moreover, this sensor less DP system tuning is unknown to the industries. Our intention of these experiments is to measure the hydrodynamic forces, in order to understand how the evaluated forces is altered under different environmental and operational conditions in SIMOPS operation. To start with, we first decided to measure drag forces when leg & spudcan moves in UP/DN direction under variable environment current. Both CFD and tank experiment is done using 3D prototype scale model of a cylindrical leg. The experimental limitation is also defined based on the tank facilities. The data is recorded during lowering and raising of the leg to see the effect on the drag force of leg- spudcan. The experimental data are recorded for current, leg speed; drag forces etc. with respect to time and average value considered for a steady state experimental case period. The evaluated results are compared with CFD results and show similar trends with acceptable error. The CFD analysis also carried out on a full-scale leg diameter to see the drag force trends. In order to understand the effect of seabed on the overall hydrodynamic force, cases were studied in which the leg was kept just a 0.1 m above seabed.

Language：English   Publishing type：Research paper (international conference proceedings)  

Ocean floor resources such as sea-floor hydrothermal deposit, methane hydrate and manganese nodule are promising resources for future ocean development. It is becoming apparent by recent research that certain amount of these resources deposit also near Japan. Though several kinds of exploration methods such as seismic exploration, a multi-beam echo sounder and a sub-bottom profiler which are equipped with a survey ship are used for the resource explorations in general, these exploration methods need a large amount of cost and efforts.
On the other hand, an autonomous underwater glider which equips an OBEM (Ocean Bottom Electromagnetometer) which has been developed in the author’s laboratory is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The buoyancy and attitude control mechanism enable the vehicle to move to the next measurement point by gliding.
The landing point for the measurement must be precisely controlled by the motion control system because the vehicle measures the slight variation of electromagnet wave on the sea bottom. The performance in a landing stage is essential for the motion control of the vehicle. Here, the motion control system of a weight shift device in the vehicle’s pressure container is developed for a landing stage. The authors attempt to make clear the performance of the controller in this report. Moreover, the characteristics of a buoyancy control device is examined by tank experiments. This unit is used to raise the vehicle to an appropriate height for the next gliding.

Language：English   Publishing type：Research paper (international conference proceedings)  

A novel exploration method for development of ocean floor resources such as sea-floor hydrothermal deposit, methane hydrate and manganese nodule is expected for effective utilization of the ocean resources.
The author has been developing underwater gliders for ocean floor resources exploration using an OBEM (Ocean Bottom Electromagnetometer). The vehicle has an ability to achieve long term continuous OBEM measurement autonomously. The vehicle is composed of a main wing for gliding and tail wings for landing point control for accurate observations. Buoyancy and center of gravity control devices, a battery, sensors and electric devices are contained in water tight vessels under the main wing.
The vehicle deployed by a research ship glides to the first observation point on the sea bottom. The vehicle measures the fluctuation of electromagnetic wave at the observation point after landing. Once the OBEM measurement at the first observation point is finished, the buoyancy of the vehicle is increased and the vehicle soars to an appropriate altitude. After that the buoyancy is decreased again and the vehicle glides to the next observation point. Repeating this procedure, the vehicle implements the autonomous OBEM measurement over a wide sea area.
In the successive measurements using OBEM, precise control of motion in landing is essential for safety operation and it is also important for accurate analysis of measured data in post process. In this report, motion control system of an underwater gliding vehicle for safety and precise landing is investigated. The motion equation of the vehicle and landing motion control method is explained. Numerical simulation results of landing operation of the underwater glider are also discussed.

Language：English   Publishing type：Research paper (other academic)  

The deepwater energy market in oil and gas has hampered, however the shallow water market continues to grow. Although the renewable energy impacting the energy market but it is mainly affecting coal based thermal power plants, while oil & gas energy market continue to grow.
The purpose of this manuscript is to find the viscous drag force on DP Jackup vessel during SIMOPS operation. The DP system calculates leg interaction forces using fixed Cd Value and fed to DP system for thrust calculation during this SIMOPS (i.e. Jacking operation+ DP station keeping).
However, during the CFD analysis, it was concluded that Cd values varies during leg transient from higher Cd value to steady state.

Language：English   Publishing type：Research paper (international conference proceedings)  

The Marine and Oil & Gas industries have increased interest in Self Propelled DP Jackups vessel to enhance the overall operational efficiency. The self-propelled jackups vessel has numerous applications such as well intervention, wind farm installation, repair, accommodation, service etc. in this cost optimization process. However due to closed proximity of operation (i.e. near to hydrocarbon platforms or other offshore assets), it has gigantic risk during the Simops Operation.
The Simops Operation of Dynamic positioning and Jacking operation has a grey area in force calculations for DP system on board which use mathematical model. The input from position reference sensors, environmental sensors to calculate relative position based on position, heading, speed and rate of turn inputs for station keeping/ DP intended operation and finally issue thrust output command. The system continues to monitor the position by taking its feedback and comparing with calculated vessel position. However, many DP jackups does not have system for hydrodynamic force measurement of leg & spudcan. This is mainly due to drag coefficient of complex leg and Spud Can geometry. The drag coefficient plays vital role in force calculation and due to non-standard shape currently industries follow approximation method. This will increase risk in station keeping under different condition and failure cases.
The intension of this study is to find the gap in existing force calculation, which is affected by drag coefficient. During the CFD analysis evaluation the effect of marine growth, leg shape, spud can, leg transit speed under variable environmental conditions are considered. The software use for CFD analysis is Ansys Aim. The vessel data used for the simulation purpose are from most popular design of jackups vessel used in offshore O&G and wind farm industry.
The study will provide drag coefficient variation in transit time domain, which has large impact on force calculation estimation for DP System.

Language：English   Publishing type：Research paper (international conference proceedings)  

A novel exploration method of ocean floor resources is expected for effective utilization of the ocean and the object area for the development expands to deeper sea area recently.
An autonomous underwater glider which equips an OBEM (Ocean Bottom Electromagnetometer) for ocean floor resources explorations is proposed in this report. The autonomous vehicle has an ability to achieve a long term continuous resources exploration autonomously. The buoyancy and attitude control mechanism enable the vehicle to move to the next measurement point by gliding. The landing point for the measurement is precisely controlled by the motion control system.
The gliding performance of the vehicle is investigated by tank and field experiments. The mathematical model of the vehicle motion is refined based on the study and numerical calculations are carried out to design the motion control system for the autonomous underwater glider for OBEM measurement.

Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English  

The dynamics and control of a towed vehicle when it changes depth and course were studied theoretically and experimentally. A mathematical model of motions of the vehicle is described in 6-degree-freedom motion equations and that of the towing cable is done using the lumped mass model. Control systems based on an optimal control theory (LQI synthesis) were developed to control the vehicle safely during the depth change. In the course change experiment the pin controller was used. The performance of the controller and the accuracy of the mathematical model of motions have been evaluated by field experiments. The towing tension was also measured in field experiments to confirm the safety of the towing table.

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Event date： 2023.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宮城県， 気仙沼市   Country：Japan  

水面下の遺跡や沈没船を発掘，保存，調査する水中考古学分野では，全世界の海域で宮殿や沈没船の発掘が行 われている.一方で，その歴史は比較的浅く海底には歴 史的，学術・技術的に価値を有する船舟類に関する遺跡 が数多く未調査のまま残されている.
海底の状態を詳細に観察しようとするとき，水中ビークルに搭載した光学カメラを用いて静止画や動画を撮影 することが有用である.海中では光の減衰や散乱の影響 によって可視距離が数メートル程度に限定される場合が 多く，太陽光が届かない水深においては照明を使用して 撮影するため，特にマリンスノーによる後方散乱による 影響が強く，可視距離が短くなる.したがって，海底を 広範囲に撮影するためには，海底の起伏や勾配に追従し， 障害物を回避しながら海底との距離を近く保ったまま水 中ビークルを高速で移動させることができる高い運動性 能が求められる.
本報告では，光学カメラによって海底を撮影する水中 曳航体の運動制御について調査し，その課題を検討する.

Event date： 2022.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Ottawa   Country：Canada  

The authors propose a towed vehicle with intentional instability for use in seafloor exploration. This towed vehicle has one pair of canard wings in addition to conventional main and tail wings. The hydrodynamic characteristics and the motion control performance of the multi-winged towed vehicle with the three control surfaces are investigated. First, CFD and experiments were conducted to investigate the effects of interference between the wings. Then, equations of the motion for the multi-winged towed vehicle were formulated and the simulations of the motion control were conducted. The calculations were performed for the longitudinal motion of the vehicle. Since this system has three control inputs (three wing angles) for two control outputs (pitch and heave), the control input to reach the target is not uniquely determined. For this reason, the authors reduced the number of control inputs by linking the angles of the tail and the canard wings at a certain ratio. The motion control simulations confirmed that the pitch and heave can be controlled almost independently, demonstrating the superiority of the multi-winged towed vehicle over conventional ones.

Repository Public URL： https://hdl.handle.net/2324/7173451

Event date： 2022.6

Language：English   Presentation type：Oral presentation (general)  

Venue：online   Country：China  

Many archaeological relics such as a wreck of an ancient ship are remains under the sea bottom and most of them are untouched because of difficulties of underwater exploration. Usual sub-bottom explorations for offshore resources such as oil and gas are carried out using seismic and sonic prospecting instruments and it is high cost and time consuming. On the other hand, archaeological relics in the relatively shallow water are explored by a sub-bottom profiler and by divers so the area which can be investigated is very limited.
The authors have been developing underwater towed vehicles and autonomous underwater gliders in the previous studies. These vehicles equip various types of instruments including an OBEM (Ocean Bottom Electro-Magnetometer). They are promising instruments for marine environment survey and ocean floor resources exploration.
In this report, a towed exploration system for archaeological relics exploration is proposed and the development of the vehicle including a motion controller is discussed. The vehicle is towed near the sea bottom to improve the accuracy of the measurement using a sonic prospector. The performance of the towed system and its motion control system are assessed by tank experiments and numerical simulations.

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島県， 広島市   Country：Japan  

水中考古学は水面下の遺跡や沈没船を発掘，保存，調査する研究分野であり，全世界の海域で宮殿や沈没船の発掘が行われているが，その歴史は比較的浅く，海底には歴史的，学術・技術的に価値を有する船舟類に関する 遺跡が数多く未調査のまま残されていると考えられる。
本報告では，水中考古学における従来の探査手法について調査し，その課題を検討する。また，鷹島神崎遺跡 の元寇沈船探査のため，浅海域を対象とする音波探査と曳航体を組み合わせた探査システムを計画し，試作機の流体力学的特性，運動制御性能について検討する。

Event date： 2021.6

Language：English   Presentation type：Oral presentation (general)  

Venue：online   Country：Greece  

The authors have been developing an autonomous underwater glider which equips an OBEM (Ocean Bottom Electro-Magnetometer). That is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The motion control system for landing of the vehicle was investigated in the previous studies. In these reports, hydrodynamic performance of the vehicle in landing is examined by CFD calculations. The bottom effect which affects the lift and drag of the wings of the glider is studied and the characteristics of the blended wing body near a sea bottom is discussed.
On the other hand, the transient motions of the vehicle such as a deployment, the motion when the vehicle changes its buoyancy for cruise are also important problems for the motion control of the vehicle. The control system might be affected by the unpredicted change of the hydrodynamic forces acting on the body and the wing in the transient conditions. Consequently, it may cause deterioration of the performance of the control system.
In this report, these transient motions are investigated based on CFD analysis. The overset mesh approach is used to simulated the sequential maneuvers in the cruising of the underwater vehicle.

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Venue：online   Country：China  

The authors have been developing an autonomous underwater glider which equips an OBEM (Ocean Bottom Electromagnetometer). That is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The buoyancy and attitude control mechanism of the vehicle enable to move to the next measurement point by gliding.
The vehicle which has a blended wing body measures the slight variation of electromagnet wave on the sea bottom and the landing point for the measurement must be precisely controlled by the motion control system. In the landing stage, it is predicted that surface effect of the sea bottom affects the hydrodynamic characteristics of the vehicle, and it might cause some problems on the motion control system of the vehicle.
The authors attempt to make clear the characteristics of the flow field around the vehicle in the vicinity of a sea bottom. The motion control system for landing of the vehicle was investigated in the previous study (Yamaguchi and Sumoto, 2019). In this report, hydrodynamic performance of the vehicle in landing is examined by CFD calculations. The surface effect by a sea bottom which affects the lift and drag of the wings of the glider is studied and the characteristics of the blended wing body near a sea bottom is discussed.

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Hawaii, USA   Country：United States  

The Dynamic Positioned (DP) Jack-up vessels currently use two popular designs of legs, (i.e. rack & chord lattices and cylindrical leg type). These two leg designs are popular and various experiment conducted in the past to evaluate the drag coefficient and drag force of these legs, but they are only available in a steady state condition. The intention of our experiment is to measure drag force and compare with CFD results. In DP vessels, mathematical model of the vessel first estimates the environmental force acting on the vessel, by using real time sensor data and then generate the counter balance thrust. The output command of force and angle is then sent to the available thrusters. However, usually, DP Jack-up vessels do not have sensor to measure the hydrodynamic force of leg &spudcan. Presently, each DP control system manufacturer for Jack-up vessels uses its own mathematical technique to achieve stability of station keeping during simultaneous operation of dynamic positioning and Jacking operation (SIMOPS). Moreover, this sensor less DP system tuning is unknown to the industries. Our intention of these experiments is to measure the hydrodynamic forces, in order to understand how the evaluated forces is altered under different environmental and operational conditions in SIMOPS operation. To start with, we first decided to measure drag forces when leg & spudcan moves in UP/DN direction under variable environment current. Both CFD and tank experiment is done using 3D prototype scale model of a cylindrical leg. The experimental limitation is also defined based on the tank facilities. The data is recorded during lowering and raising of the leg to see the effect on the drag force of leg- spudcan. The experimental data are recorded for current, leg speed; drag forces etc. with respect to time and average value considered for a steady state experimental case period. The evaluated results are compared with CFD results and show similar trends with acceptable error. The CFD analysis also carried out on a full-scale leg diameter to see the drag force trends. In order to understand the effect of seabed on the overall hydrodynamic force, cases were studied in which the leg was kept just a 0.1 m above seabed.

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Hawaii, USA   Country：United States  

Ocean floor resources such as sea-floor hydrothermal deposit, methane hydrate and manganese nodule are promising resources for future ocean development. It is becoming apparent by recent research that certain amount of these resources deposit also near Japan. Though several kinds of exploration methods such as seismic exploration, a multi-beam echo sounder and a sub-bottom profiler which are equipped with a survey ship are used for the resource explorations in general, these exploration methods need a large amount of cost and efforts.
On the other hand, an autonomous underwater glider which equips an OBEM (Ocean Bottom Electromagnetometer) which has been developed in the author’s laboratory is a hopeful instrument for the ocean floor resources explorations. The autonomous vehicle has an ability to achieve a continuous resource exploration autonomously for a long term. The buoyancy and attitude control mechanism enable the vehicle to move to the next measurement point by gliding.
The landing point for the measurement must be precisely controlled by the motion control system because the vehicle measures the slight variation of electromagnet wave on the sea bottom. The performance in a landing stage is essential for the motion control of the vehicle. Here, the motion control system of a weight shift device in the vehicle’s pressure container is developed for a landing stage. The authors attempt to make clear the performance of the controller in this report. Moreover, the characteristics of a buoyancy control device is examined by tank experiments. This unit is used to raise the vehicle to an appropriate height for the next gliding.

Event date： 2018.11 - 2018.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Makuhari Messe, Chiba   Country：Japan  

Event date： 2018.11

Language：English   Presentation type：Oral presentation (general)  

Venue：千葉県， 柏市   Country：Japan  

The deepwater energy market in oil and gas has hampered, however the shallow water market continues to grow. Although the renewable energy impacting the energy market but it is mainly affecting coal based thermal power plants, while oil & gas energy market continue to grow.
The purpose of this manuscript is to find the viscous drag force on DP Jackup vessel during SIMOPS operation. The DP system calculates leg interaction forces using fixed Cd Value and fed to DP system for thrust calculation during this SIMOPS (i.e. Jacking operation+ DP station keeping).
However, during the CFD analysis, it was concluded that Cd values varies during leg transient from higher Cd value to steady state.

Event date： 2018.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan   Country：Japan  

Event date： 2018.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan   Country：Japan  

Event date： 2017.6 - 2017.7

Language：English   Presentation type：Oral presentation (general)  

Venue：San Francisco, California   Country：United States  

Event date： 2016.6 - 2016.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Rhodes   Country：Greece  

Event date： 2016.5 - 2015.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター（福岡市博多区）   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京工業大学　大岡山キャンパス   Country：Japan  

Event date： 2015.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京大学生産技術研究所   Country：Japan  

Event date： 2015.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京大学生産技術研究所   Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鳥取大学　鳥取キャンパス   Country：Japan  

Event date： 2014.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎ブリックホール(長崎市茂里町2-38)   Country：Japan  

Event date： 2014.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎ブリックホール(長崎市茂里町2-38)   Country：Japan  

Event date： 2014.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎ブリックホール(長崎市茂里町2-38)   Country：Japan  

Event date： 2014.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台国際センター（仙台市）   Country：Japan  

Event date： 2014.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台国際センター（仙台市）   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府立大学 I-siteなんば（大阪市浪速区）   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府立大学 I-siteなんば（大阪市浪速区）   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府立大学 I-siteなんば（大阪市浪速区）   Country：Japan  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府立大学 I-siteなんば（大阪市浪速区）   Country：Japan  

Event date： 2013.6 - 2013.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Anchorage   Country：United States  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2012.12

Presentation type：Oral presentation (general)  

Venue：The Evergreen International Convention Center, Taipei   Country：Taiwan, Province of China  

Event date： 2012.11

Presentation type：Oral presentation (general)  

Venue：東京大学柏キャンパス（千葉県柏市）   Country：Japan  

Event date： 2012.11

Presentation type：Oral presentation (general)  

Venue：東京大学柏キャンパス（千葉県柏市）   Country：Japan  

Event date： 2012.11

Presentation type：Oral presentation (general)  

Venue：東京大学柏キャンパス（千葉県柏市）   Country：Japan  

Event date： 2012.11

Presentation type：Oral presentation (general)  

Venue：東京大学柏キャンパス（千葉県柏市）   Country：Japan  

Event date： 2012.11

Presentation type：Oral presentation (general)  

Venue：東京大学柏キャンパス（千葉県柏市）   Country：Japan  

Event date： 2012.6

Presentation type：Oral presentation (general)  

Venue：Rhodes   Country：Greece  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：鹿児島大学水産学部   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：神戸市産業振興センター   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：神戸市産業振興センター   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：神戸市産業振興センター   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：神戸市産業振興センター   Country：Japan  

Event date： 2012.5

Presentation type：Oral presentation (general)  

Venue：神戸市産業振興センター   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：シーモールパレス（下関市）   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：シーモールパレス（下関市）   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：シーモールパレス（下関市）   Country：Japan  

Event date： 2011.11

Presentation type：Oral presentation (general)  

Venue：シーモールパレス（下関市）   Country：Japan  

Event date： 2011.6

Presentation type：Oral presentation (general)  

Venue：Maui, Hawaii   Country：United States  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター(福岡市博多区）   Country：Japan  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター(福岡市博多区）   Country：Japan  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター(福岡市博多区）   Country：Japan  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター(福岡市博多区）   Country：Japan  

Event date： 2011.5

Presentation type：Oral presentation (general)  

Venue：福岡県中小企業振興センター(福岡市博多区）   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：アルカスSASEBO(佐世保市）   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：アルカスSASEBO(佐世保市）   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：アルカスSASEBO(佐世保市）   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：アルカスSASEBO(佐世保市）   Country：Japan  

Event date： 2010.11

Presentation type：Oral presentation (general)  

Venue：アルカスSASEBO(佐世保市）   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：Beijing   Country：China  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：ワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：ワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：ワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2010.6

Presentation type：Oral presentation (general)  

Venue：ワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：熊本県荒尾市   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：熊本県荒尾市   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：熊本県荒尾市   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：熊本県荒尾市   Country：Japan  

Event date： 2009.11

Presentation type：Oral presentation (general)  

Venue：熊本県荒尾市   Country：Japan  

Event date： 2009.6

Presentation type：Oral presentation (general)  

Venue：Osaka   Country：Japan  

Event date： 2009.6

Presentation type：Oral presentation (general)  

Venue：Osaka   Country：Japan  

Event date： 2009.5

Presentation type：Oral presentation (general)  

Venue：兵庫県神戸市   Country：Japan  

Event date： 2009.5

Presentation type：Oral presentation (general)  

Venue：兵庫県神戸市   Country：Japan  

Event date： 2008.11

Presentation type：Oral presentation (general)  

Venue：広島県呉市   Country：Japan  

Event date： 2008.11

Presentation type：Oral presentation (general)  

Venue：広島県呉市   Country：Japan  

Event date： 2008.11

Presentation type：Oral presentation (general)  

Venue：広島県呉市   Country：Japan  

Event date： 2008.11

Presentation type：Oral presentation (general)  

Venue：広島県呉市   Country：Japan  

Event date： 2008.11

Presentation type：Oral presentation (general)  

Venue：広島県呉市   Country：Japan  

Event date： 2008.10

Presentation type：Oral presentation (general)  

Venue：Chiba   Country：Japan  

Event date： 2008.10

Presentation type：Oral presentation (general)  

Venue：Chiba   Country：Japan  

Event date： 2008.10

Presentation type：Oral presentation (general)  

Venue：Chiba   Country：Japan  

Event date： 2008.7

Presentation type：Oral presentation (general)  

Venue：Vancouver   Country：Canada  

Event date： 2008.5

Presentation type：Oral presentation (general)  

Venue：長崎市　ウェルシティ長崎   Country：Japan  

Event date： 2008.3

Presentation type：Symposium, workshop panel (public)  

Venue：日本大学理工学部駿河台キャンパス   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：愛媛県今治市ホテルアジュール   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：愛媛県今治市ホテルアジュール   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：愛媛県今治市ホテルアジュール   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：愛媛県今治市ホテルアジュール   Country：Japan  

Event date： 2007.7

Presentation type：Oral presentation (general)  

Venue：Corinthia Lisboa Hotel, Lisbon   Country：Portugal  

Event date： 2007.5 - 2008.5

Presentation type：Oral presentation (general)  

Venue：池袋サンシャインシティ文化会館   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：池袋サンシャインシティ文化会館   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：池袋サンシャインシティ文化会館   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：池袋サンシャインシティ文化会館   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：神戸国際会議場   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：長崎県ハウステンボス   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：山口県下関市   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：山口県下関市   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：山口県下関市   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：San Francisco   Country：United States  

Presentation type：Oral presentation (general)  

Venue：神戸国際会議場   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：神戸国際会議場   Country：Japan  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Type：Academic society, research group, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：6

Number of peer-reviewed articles in Japanese journals：4

Proceedings of International Conference Number of peer-reviewed papers：10

Type：Competition, symposium, etc. 

Number of participants：600

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：4

Number of peer-reviewed articles in Japanese journals：5

Proceedings of International Conference Number of peer-reviewed papers：8

Type：Competition, symposium, etc. 

Number of participants：600

Type：Competition, symposium, etc. 

Number of participants：250

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：0

Number of peer-reviewed articles in Japanese journals：2

Proceedings of International Conference Number of peer-reviewed papers：13

Type：Competition, symposium, etc. 

Number of participants：600

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：5

Number of peer-reviewed articles in Japanese journals：1

Proceedings of International Conference Number of peer-reviewed papers：8

Type：Competition, symposium, etc. 

Number of participants：600

Type：Competition, symposium, etc. 

Number of participants：500

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：6

Number of peer-reviewed articles in Japanese journals：1

Proceedings of International Conference Number of peer-reviewed papers：7

Type：Competition, symposium, etc. 

Number of participants：600

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Number of participants：600

Type：Competition, symposium, etc. 

Number of participants：500

Type：Academic society, research group, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：200

Type：Academic society, research group, etc. 

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Number of participants：180

Type：Competition, symposium, etc. 

Number of participants：250

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Number of participants：300

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：500

Type：Competition, symposium, etc. 

Number of participants：500