Path Replanning Method for an AUV in Natural Hydrothermal Vent Fields: Toward 3D Imaging of a Hydrothermal Chimney

2014 ◽  
Vol 48 (3) ◽  
pp. 104-114 ◽  
Author(s):  
Yoshiki Sato ◽  
Toshihiro Maki ◽  
Ayaka Kume ◽  
Takumi Matsuda ◽  
Takashi Sakamaki ◽  
...  
Keyword(s):  
Hydrothermal Vent ◽  
Autonomous Underwater Vehicles ◽  
Visual Observation ◽  
Color Information ◽  
High Coverage ◽  
Human Control ◽  
Kagoshima Bay ◽  
Sufficient Energy ◽  
Shallow Seas ◽  
Limited Coverage

AbstractAutonomous underwater vehicles (AUVs) can operate without the need for human control or tether cables as long as there is sufficient energy. AUVs have recently been used for seafloor imaging. Visual observation by AUVs provides high-resolution color information of the seafloor. However, conventional observation techniques that follow a prespecified path offer limited coverage because it is impossible for operators to build a suitable path in unknown rough terrain. A flawed prespecified path will produce incomplete observation. If unobserved areas are found during postprocessing, another dive is necessary, which increases the total cost. To overcome this problem, the authors have proposed a path replanning method to realize high-coverage observation in one dive. With this method, the AUV evaluates unobserved areas after the first prespecified observation; if unobserved areas are found, the AUV recreates an appropriate path to cover what was missed. The validity of the proposed method was previously evaluated using an artificial target in a tank and in shallow seas at a depth of approximately 35 m. In this study, the feasibility of the method was validated in a more challenging setting: experimental data were taken from a hydrothermal vent field in Kagoshima Bay, Japan.

A Method for Obtaining High-Coverage 3D Images of Rough Seafloor Using AUV – Real-Time Quality Evaluation and Path-Planning –

2013 ◽  
Vol 25 (2) ◽  
pp. 364-374 ◽  
Author(s):  
Ayaka Kume ◽  
◽  
Toshihiro Maki ◽  
Takashi Sakamaki ◽  
Tamaki Ura
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Quality Evaluation ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
New Method ◽  
3D Image ◽  
High Coverage ◽  
3D Images ◽  
Kagoshima Bay

Autonomous Underwater Vehicles (AUVs) are often used for seafloor exploration, and some AUVs are now being deployed to obtain detailed photomosaics of the seafloor. However, it is difficult for the results to be evaluated on-site, so the image maps obtained often have unscanned areas caused by occlusions, disturbances, etc. In order to improve the coverage of a map, operators have to plan a new path and then redeploy the AUV. This process is quite timeconsuming and troublesome. The authors propose a new method for an AUV to obtain a full-coverage 3D image of a rough, unknown seafloor in a single deployment. First, the AUV observes the seafloor by following a pre-determined path. Second, the AUV calculates the following on-site and based on the data obtained: 3D bathymetry map, unscanned areas on the map, and the next path that can be taken to image the unscanned areas effectively. Then, the AUV follows the new path to obtain better results. The performance of this proposed method is verified in both tank experiments and by simulation. In the experiments, the AUV “Tri-TON” succeeds in generating a route for a second observation, and the coverage increases from 73% to 82%. The performance of the method on the actual seafloor is verified using the results of the tank experiments and the bathymetry data on a chimney in Kagoshima Bay, Japan.

scholarly journals Polyclonal symbiont populations in hydrothermal vent tubeworms and the environment

2019 ◽  
Vol 286 (1896) ◽  
pp. 20181281 ◽  
Author(s):  
Julia Polzin ◽  
Philip Arevalo ◽  
Thomas Nussbaumer ◽  
Martin F. Polz ◽  
Monika Bright
Keyword(s):  
Hydrothermal Vent ◽  
Low Frequency ◽  
Gene Sequencing ◽  
Housekeeping Genes ◽  
Partner Choice ◽  
Sequence Variability ◽  
Riftia Pachyptila ◽  
Free Living ◽  
High Coverage ◽  
Dominant Genotype

Horizontally transmitted symbioses usually house multiple and variable symbiont genotypes that are acquired from a much more diverse environmental pool via partner choice mechanisms. However, in the deep-sea hydrothermal vent tubeworm Riftia pachyptila (Vestimentifera, Siboglinidae), it has been suggested that the Candidatus Endoriftia persephone symbiont is monoclonal. Here, we show with high-coverage metagenomics that adult R. pachyptila house a polyclonal symbiont population consisting of one dominant and several low-frequency variants. This dominance of one genotype is confirmed by multilocus gene sequencing of amplified housekeeping genes in a broad range of host individuals where three out of four loci ( atpA , uvrD and recA ) revealed no genomic differences, while one locus ( gyrB ) was more diverse in adults than in juveniles. We also analysed a metagenome of free-living Endoriftia and found that the free-living population showed greater sequence variability than the host-associated population. Most juveniles and adults shared a specific dominant genotype, while other genotypes can dominate in few individuals. We suggest that although generally permissive, partner choice is selective enough to restrict uptake of some genotypes present in the environment.

Low-Altitude and High-Speed Terrain Tracking Method for Lightweight AUVs

2018 ◽  
Vol 30 (6) ◽  
pp. 971-979 ◽  
Author(s):  
Toshihiro Maki ◽  
Yukiyasu Noguchi ◽  
Yoshinori Kuranaga ◽  
Kotohiro Masuda ◽  
Takashi Sakamaki ◽  
...  
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Autonomous Underwater Vehicles ◽  
Vertical Plane ◽  
Potential Method ◽  
Visual Observation ◽  
Doppler Velocity ◽  
Navigation Systems ◽  
Inertial Navigation Systems ◽  
Constant Altitude

This paper proposes a new method for cruising-type autonomous underwater vehicles (AUVs) to track rough seafloors at low altitudes while also maintaining a high surge velocity. Low altitudes are required for visual observation of the seafloor. The operation of AUVs at low altitudes and high surge velocities permits rapid seafloor imaging over a wide area. This method works without high-grade sensors, such as inertial navigation systems (INS), Doppler velocity logs (DVL), or multi-beam sonars, and it can be implemented in lightweight AUVs. The seafloor position is estimated based on a reflection intensity map defined on a vertical plane, using measurements from scanning sonar and basic sensors of depth, attitude, and surge velocity. Then, based on the potential method, a reference pitch angle is generated that allows the AUV to follow the seafloor at a constant altitude. This method was implemented in the AUV HATTORI, and a series of sea experiments were carried out to evaluate its performance. HATTORI (Highly Agile Terrain Tracker for Ocean Research and Investigation) is a lightweight and low-cost testbed designed for rapid and efficient imaging of rugged seafloors, such as those containing coral reefs. The vehicle succeeded in following a rocky terrain at an altitude of approximately 2 m with a surge velocity of approximately 0.8 m/s. This paper also presents the results of sea trials conducted at Ishigaki Island in 2017, where the vehicle succeeded in surveying the irregular, coral-covered seafloor.

Docking Method for Hovering-Type AUVs Based on Acoustic and Optical Landmarks

2018 ◽  
Vol 30 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Toshihiro Maki ◽  
◽  
Yoshiki Sato ◽  
Takumi Matsuda ◽  
Kotohiro Masuda ◽  
...  
Keyword(s):  
Power Transmission ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Human Intervention ◽  
Contact Charging ◽  
Human Control ◽  
Docking Method ◽  
Position And Orientation

Autonomous underwater vehicles (AUVs) have the advantage of not requiring tether cables or human control; however, they have limited energy, and must be recovered before their batteries drain completely. To charge AUV batteries efficiently, in-situ charging systems have attracted much attention. This study proposes a method for hovering-type AUVs to dock at a seafloor station, for long-term deployment of the system with minimum human intervention. In the proposed method, an AUV docks at a seafloor station autonomously, based on both acoustic and optical landmarks attached to the station. The AUV stochastically estimates its position and orientation with regard to the station, and controls itself to land on the exact docking spot at the station. When docking is completed, the station begins electric power transmission via non-contact charging devices. The proposed method was evaluated on the AUV Tri-TON 2, and a seafloor station testbed. The vehicle succeeded in autonomous docking at the station in both the tank and sea trials. Non-contact charging during docking was also verified during the tank experiments, using the non-contact charging devices developed by our group.

Sulphur sources for chemoautotrophic nutrition of shallow water vestimentiferan tubeworms in Kagoshima Bay

2002 ◽  
Vol 82 (4) ◽  
pp. 537-540 ◽  
Author(s):  
Tomoyuki Miura ◽  
Munetomo Nedachi ◽  
Jun Hashimoto
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vent ◽  
Isotopic Ratios ◽  
Animal Tissues ◽  
Volcanic Gas ◽  
Sulphur Source ◽  
Kagoshima Bay ◽  
Volcanic Source ◽  
Vestimentiferan Tubeworm ◽  
Sulphur Species

To elucidate the sulphur sources for chemoautotrophy by the symbiotic bacteria of a vestimentiferan tubeworm, Lamellibrachia satsuma, living in Kagoshima Bay at depths of 80–100 m, we analysed the sulphur isotopic ratios of the animal tissues and compared them with environmental sulphur species collected in the field. Animals that had been maintained in an aquarium for over a year and supplied a known sulphur source were also investigated. The gas emitted from volcanic source in Kagoshima Bay contained rather heavy sulphide (+12·7 to +22·9‰ δ34S) compared with deep-sea hydrothermal vent systems (0 to +5‰). The tissue of the tubeworms contained very light sulphide (−21·5 to −25·9‰). It is inferred from the analysis of the aquarium-maintained specimens that the fractionation by the tubeworm or its symbiont was <1·5‰. The sulphur source assimilated by the tubeworms in the field is therefore inferred to have δ ratio −19·1 to −24·6‰. This means that only 9·7 to 25·0% of the sulphur in the worm tissues can be derived from the volcanic gas and the rest must come from other sources, such as microbial activity in the bottom sediment.

scholarly journals Some Observations on Human Control of a Bicycle

2009 ◽  
Author(s):  
J. D. G. Kooijman ◽  
A. L. Schwab ◽  
Jason K. Moore
Keyword(s):  
Visual Observation ◽  
Upper Body ◽  
Lateral Motion ◽  
Forward Speed ◽  
Steering Control ◽  
Human Control ◽  
Control Actions ◽  
Knee Movement ◽  
Bicycle Rider ◽  
Pedaling Frequency

The purpose of this study is to identify human control actions in normal bicycling. The task under study is the stabilization of the mostly unstable lateral motion of the bicycle-rider system. This is done by visual observation of the rider and measuring the vehicle motions. The observations show that very little upper-body lean occurs and that stabilization is done by steering control actions only. However, at very low forward speed a second control is introduced to the system: knee movement. Moreover, all control actions are performed at the pedaling frequency, whilst the amplitude of the steering motion increases rapidly with decreasing forward speed.

scholarly journals A new species of Nebalia (Crustacea, Leptostraca) from a hydrothermal field in Kagoshima Bay, Japan

ZooKeys ◽  
2019 ◽  
Vol 897 ◽  
pp. 1-18
Author(s):  
Takuma Hirata ◽  
Yoshihiro Fujiwara ◽  
Tomohiko Kikuchi
Keyword(s):  
New Species ◽  
Hydrothermal Vent ◽  
Hydrothermal Field ◽  
Lateral Margin ◽  
Distal Margin ◽  
Proximal Half ◽  
Kagoshima Bay ◽  
Mandibular Palp ◽  
Distribution And Ecology ◽  
A New Species

A new species of Leptostraca, Nebalia tagirisp. nov. is described and illustrated. This species was sampled from 200 m depth at a hydrothermal field in Wakamiko Caldera of Kagoshima Bay, Japan. Nebalia tagirisp. nov. is different from known Nebalia species as follows: rostral length 2.4 times as long as width; article 4 of antennule with 3–5 robust distal spines; antennular scale approximately twice as long as wide; article 3 of antenna with eight spines and nine spine-like setae along proximal half, two thin setae and six spine-like setae on external lateral face, six spines and four simple setae on distal margin; article 1 of second maxilla longer than article 2; article 2 of mandibular palp with two thin setae; exopod of pleopod 1 with 21 spines along lateral margin; furcal rami longer than combined length of pleonite 7 and telson; rounded denticles of pleonite 6 and 7; anal-plates ‘shoulder’ not distinct. Furthermore, this specimen is the first genus Nebalia found in the hydrothermal vent. The distribution and ecology of this new species is also discussed and a key to all species of Nebalia is provided.

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