scholarly journals A method for on-line water current velocity estimation using low-cost autonomous underwater vehicles

2020 ◽  
Author(s):  
Christopher R. Dolan
Keyword(s):  
Current Velocity ◽  
Low Cost ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Velocity Estimation ◽  
Water Current ◽  
Water Current Velocity ◽  
On Line

scholarly journals A Low-Cost Electromagnetic Docking Guidance System for Micro Autonomous Underwater Vehicles

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 682 ◽  
Author(s):  
Shilin Peng ◽  
Jingbiao Liu ◽  
Junhao Wu ◽  
Chong Li ◽  
Benkun Liu ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Guidance System ◽  
Electromagnetic Signal ◽  
Spatiotemporal Resolution ◽  
Search Coil ◽  
Wide Range ◽  
Processing Subsystem

As important observational platforms for the Smart Ocean concept, autonomous underwater vehicles (AUVs) that perform long-term observation in fleets are beneficial because they provide large-scale sampling data with a sufficient spatiotemporal resolution. Therefore, a large number of low-cost micro AUVs with docking capability for power recharge and data transmission are essential. This study designed a low-cost electromagnetic docking guidance (EMDG) system for micro AUVs. The EMDG system is composed of a transmitter coil located on the dock and a three-axial search coil magnetometer acting as a receiver. The search coil magnetometer was optimized for small sizes while maintaining sufficient sensitivity. The signal conditioning and processing subsystem was designed to calculate the deflection angle (β) for docking guidance. Underwater docking tests showed that the system can detect the electromagnetic signal and successfully guide AUV docking. The AUV can still perform docking in extreme positions, which cannot be realized through normal optical or acoustic guidance. This study is the first to focus on the EM guidance system for low-cost micro AUVs. The search coil sensor in the AUV is inexpensive and compact so that the system can be equipped on a wide range of AUVs.

scholarly journals Mid-water current aided localization for autonomous underwater vehicles

2016 ◽  
Vol 40 (7) ◽  
pp. 1207-1227 ◽  
Author(s):  
Lashika Medagoda ◽  
Stefan B. Williams ◽  
Oscar Pizarro ◽  
James C. Kinsey ◽  
Michael V. Jakuba
Keyword(s):  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Water Current

scholarly journals THE PHYSICAL ENVIRONMENT IN CORAL REEFS OF THE TAYRONA NATIONAL NATURAL PARK (COLOMBIAN CARIBBEAN) IN RESPONSE TO SEASONAL UPWELLING

2016 ◽  
Vol 43 (1) ◽  
Author(s):  
Elisa Bayraktarov ◽  
Martha L Bastidas Salamanca ◽  
Christian Wild
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Current Velocity ◽  
Physical Environment ◽  
Water Current ◽  
Exposed Site ◽  
Water Currents ◽  
Natural Park ◽  
Water Current Velocity ◽  
Sheltered Site

Coral reefs are subjected to physical changes in their surroundings including wind velocity, water temperature, and water currents that can affect ecological processes on different spatial and temporal scales. However, the dynamics of these physical variables in coral reef ecosystems are poorly understood. In this context, Tayrona National Natural Park (TNNP) in the Colombian Caribbean is an ideal study location because it contains coral reefs and is exposed to seasonal upwelling that strongly changes all key physical factors mentioned above. This study therefore investigated wind velocity and water temperature over two years, as well as water current velocity and direction for representative months of each season at a windand wave-exposed and a sheltered coral reef site in one exemplary bay of TNNP using meteorological data, temperature loggers, and an Acoustic Doppler Current Profiler (ADCP) in order to describe the spatiotemporal variations of the physical environment. Findings revealed that water temperatures (28.7 ± 0.8 °C and maximal 30.3 °C during non-upwelling; 25.1 ± 1.7 °C and minimal 20.3 °C during upwelling) exhibited no significant differences between sites and were negatively correlated with wind velocities (0.4 ± 0.3 m s-1 during non-upwelling and 1.8 ± 1.0 m s-1 with a maximum of 4.1 m s-1 during upwelling). Water current velocity was significantly higher at the exposed compared to the sheltered site during non-upwelling periods at a water depth of 8-10 m. During upwelling, water current velocities were also higher at the exposed site (6.4 cm s-1 exposed and 5.9 cm s-1 sheltered), but when wind speed surpassed 1.7 m s-1, no spatial differences occurred. Water currents showed a clockwise circulation during upwelling following the wind fields, but no clear circulation pattern during non-upwelling. Significant positive correlation between wind and water current velocity was detected at the sheltered, but not at the exposed site. Wind-stress at the exposed site affected water currents throughout the entire water column (at least 10 m deep) during both seasons, but reached only until 3-4 m water depth at the sheltered site during non-upwelling and down to 10 m during upwelling. Consequently, organisms at the exposed site experience constantly high water current exposure throughout the year. This may explain the pronounced site-specific reef community composition differences as water current velocity and circulation control distribution of invertebrate larvae and supply with plankton and essential nutrients.

Low-Cost, Man-Portable Autonomous Underwater Vehicles for Rapid Environmental Assessment

2008 ◽  
Vol 42 (4) ◽  
pp. 4-11 ◽  
Author(s):  
Michael Laszlo Incze
Keyword(s):  
Environmental Assessment ◽  
Low Cost ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Environmental Data ◽  
Spatial And Temporal Variability ◽  
Data Sets ◽  
Sensing Platforms ◽  
Near Shore ◽  
Development And Validation

The requirements to rapidly characterize environmental conditions in dynamic near-shore waters have greatly outpaced the developing inventory of traditional resources to conduct this sampling. Research vessels, remote sensors, and networked in situ sensing platforms (fixed and drifting) are often limited in availability, capability, and/or adaptability, with the result that surveys can not be rapidly conducted in areas of immediate concern to communities, industry, and military defense. Autonomous underwater vehicles (AUVs) have been evolving over the past decade, with the ability to provide rapid environmental assessment as one of the primary objectives. However, the trade-off of cost and capability limited early designs and prohibited broad and effective utilization of these platforms for environmental data-collection missions. AUVs capable of sustained performance for sampling dynamic parameters in areas of high spatial and temporal variability were too costly, both in terms of procurement and operation, and lower cost AUVs did not have sufficient performance for operating in these challenging near-shore conditions. The development of low-cost, lightweight vehicles for these missions has only recently occurred, enabling responsive, multi-platform surveys to capture synoptic characterizations of near-shore waters with sufficient resolution to support data-centric 3-D models and provide baseline data sets for development and validation of physics-based forecasting models. Recent survey operations with one candidate class of AUVs developed by OceanServer Technology, Inc. reveal the hardware/software status of state-of-the-art designs and provide a basis for developing survey strategies essential to effective mission planning.

scholarly journals Autonomous underwater vehicles: future platforms for fisheries acoustics

2003 ◽  
Vol 60 (3) ◽  
pp. 684-691 ◽  
Author(s):  
Paul G Fernandes ◽  
Pete Stevenson ◽  
Andrew S Brierley ◽  
Frederick Armstrong ◽  
E.John Simmonds
Keyword(s):  
Science Fiction ◽  
Low Cost ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Three Dimensions ◽  
The North ◽  
Technological Advances ◽  
The North Sea ◽  
Fisheries Acoustics ◽  
Scientific Facts

Abstract Autonomous underwater vehicles (AUVs) are unmanned submersibles that can be pre-programmed to navigate in three dimensions under water. The technological advances required for reliable deployment, mission control, performance, and recovery of AUVs have developed considerably over the past 10 years. Currently, there are several vehicles operating successfully in the offshore industries as well as in the applied and academic oceanographic sciences. This article reviews the application of AUVs to fisheries- and plankton-acoustics research. Specifications of the main AUVs currently in operation are given. Compared to traditional platforms for acoustic instruments, AUVs can sample previously impenetrable environments such as the sea surface, the deep sea, and under-sea ice. Furthermore, AUVs are typically small, quiet, and have the potential to operate at low cost and be unconstrained by the vagaries of weather. Examples of how these traits may be utilized in fisheries-acoustics science are given with reference to previous work in the North Sea and Southern Ocean and to potential future applications. Concurrent advances in multi-beam sonar technology and species identification, using multi-frequency and broadband sonars, will further enhance the utility of AUVs for fisheries acoustics. However, before many of the more prospective applications can be accomplished, advances in power-source technology are required to increase the range of operation. The paper ends by considering developments that may turn AUVs from objects sometimes perceived as science fiction into instruments used routinely to gather scientific facts.

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