Small Remotely Operated Vehicle Research Articles

Sediment penetration performance of a portable underwater robot for core sampling

AbstractAs described in this paper, we investigate the sediment penetration performance of a portable underwater robot with a helical screw pipe using marine thrusters with limited force. First, we derive a mathematical model based on an empirical and simple method using the undrained shear strength of cohesive soil to provide a rough estimate of maximum penetration depths. Then, we perform numerical analysis for estimating the maximum depth of sediment penetration and for designing a sampling pipe. Additionally, we use experimentation to investigate the relation between the penetration depth of the helical screw pipe and the force of marine thrusters mounted on the portable underwater robot. After testing the penetration performance in a water tank, we conduct a field experiment at Lake Biwa and obtain results of the penetration depths. The maximum penetration into the lake sediment is at least 0.30 m. The results demonstrated the possibility of using the derived mathematical model to make a rough estimation of the maximum penetration depth for clay sediments. Additionally, we can use non‐powerful thrusters equipped with small autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) for sediment sampling. The proposed method is also applicable for the installation of underwater sensors using small AUVs and ROVs.

Proposed Mathematical Modeling of Small Remotely Operated Vehicle (ROV) Movement

In designing of Remotely Operated Vehicle (ROV), the most important issue is how to formulate the movements of the vehicle. This paper proposes the mathematical model of ROV movement. Combination of statics disciplines and dynamics of ROV movement are needed to formulate the mathematical model of ROV. Statics refers to the forces and moments that work on the physical system around the equilibrium point, dynamics refers to the effect of force on the movement of the object. Linear mathematical models analyzed can be combined or separated by taking into account the circumstances surrounding environment such as velocity vector of the linear state of the vehicle body (surge, sway and up) and angular (roll, yaw and pitch). Simulation results show that the movement of vehicles, both basic and combined movements have reliable characteristics.

Habitats and fish communities at mesophotic depths in the Mexican Pacific

AbstractAimMesophotic ecosystems, found at the limit of light penetration in the ocean, are rich in biodiversity and harbour unique ecological communities. However, they remain among the least studied habitat zones on earth due to the high costs and technological limitations. Here, we characterize mesophotic communities in two marine reserves across a range of habitat types, depths and temperatures using submersible technologies, with the goal of understanding the processes that structure these communities across biogeographical regions.LocationThe Bay of La Paz and the Revillagigedo Archipelago, Mexico.TaxaFish and algal species.MethodsWe used a small and inexpensive remotely operated vehicle (ROV) to conduct roving‐swim surveys of major habitat types in depths from 12 to 94 m. With the resulting binary data on the presence of fish species, we used generalized linear mixed models and canonical correspondence analysis to determine whether biogenic habitat, depth and/or temperature best explained species richness and community structure across reef and non‐reef substrate.ResultsWe identified 72 species or genera, including new depth records for nine fish species and a new geographical record for one fish species. Our surveys included large undocumented rhodolith beds (free‐living coralline algae) and mesophotic algal communities, in addition to diverse communities of soft corals and sponges. Fish species richness was positively associated with rocky substrate and warmer water, and reef fish communities differed significantly by depth, temperature and biogenic habitat.Main conclusionOur results highlight the importance of biogenic habitat in structuring communities across gradients of depth and temperature. We also demonstrate the effectiveness of a small and economical ROV for conducting mesophotic surveys in remote regions. Our methods and results provide a framework that can be used to greatly increase the biogeographical and taxonomic scope of mesophotic research, especially for readily identifiable taxa such as fish.

Body Design Concept of Remotely Operated Vehicle (ROV) of Observation Class with the Method of Concept Screening and Concept Scoring

The Remotely Operated Vehicle (ROV) underwater observation equipment has previously been developed, but it had restriction for not being hydrodynamic still due to the unique conditions of the Sunda Strait waters. This study aims to further develop the previously developed ROV by improving the design structure of the ROV body. The method of design concept selection used was concept screening and concept scoring. In concept screening, the initial concept was evaluated relatively to the same preferences using screening matrices. On the other hand the Concept Scoring was conducted by determining the relative performance value which was the assessment used to evaluate how the comparison between concepts and number as the comparison. The result of the study obtained the selected design concept, which was small ROV with streamlined / half-streamlined body geometry which had rear-middle rotor configuration as motion component of hydrodynamic 3 DOF (surge, heave, and yaw).

184 水産資源の管理支援用小型ROVの開発

184 水産資源の管理支援用小型ROVの開発

Comparison of small remotely operated vehicles and diver-operated video of circalittoral benthos

Underwater video transect methods using small remotely operated vehicles (ROVs) and diver-operated video (DOV) are commonly used in benthic biodiversity assessments. Constraints posed by deeper waters have made surveys of the circalittoral zone (>30 m depth), a particularly challenging problem. Here we compare benthic diversity metrics and cluster analyses obtained with ROV and DOV between 45 and 65 m depth off southwest Iberia, across local (tens to hundreds of meters) and regional scales (tens of kilometers). Results showed no difference between methods in terms of the benthic species richness, taxonomic distinctness, and beta diversity, but only minor differences in the spatial structure depicted at the regional level. At the local scale, DOV performed better at discriminating patterns likely because of the divers visual acuity. We found that small ROV and DOV are reliable and comparable methods for the study of circalittoral benthic assemblages and can be used in a complimentary way to detect the greatest amount of variation in benthic ecosystems. Our study facilitates the understanding of capabilities and limitations of two underwater video methods and provides important insight into choice of the most appropriate technique.

1P1-B06 小型遠隔操作型水中ロボットの開発

1P1-B06 小型遠隔操作型水中ロボットの開発

ダイバーとの比較からみた魚礁での無人機の魚類観察能力について

Recently underwater observations have begun with small ROVs (Remotely operated vehicle) to observe marine biological resources. The ROV has several advantages compared to diver, because of less limits of observation time and working depth. ROVs are expected to be a good method for biological study around artificial fish reefs. The ability of small observation ROV and divers to distinguish fishes were compared at four characteristic bottom sites. As the result, the ability of ROV was not good enough at the bad visibility areas where young fishes inhabited, but was good at flat bottom areas and relatively good at the artificial reef. In regard to the number of fish species found at the artificial fish reefs settled at a depth of 30m, results of 20 min observations by two divers were superior to those of 360 min ROV observations. When using the ROV for the fishery research in artificial fish reef grounds, the results obtainable are unsuitable to quantitative analysis and extreme care must also be taken not so as to stragle the ROV's cable with fish reefs.