Autonomous underwater vehicle
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An autonomous underwater vehicle (AUV) is a robot which travels underwater. In military applications, AUVs are also known as unmanned undersea vehicles (UUVs). AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles (ROVs) -- controlled and powered from the surface by an operator/pilot via an umbilical.
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[edit] History
Some of the first AUVs were developed by the Applied Physics Laboratory at the University of Washington as early as 1957. The "Special Purpose Underwater Research Vehicle", or SPURV, was used to study diffusion, acoustic transmission, and submarine wakes.
Other early AUVs were developed at the Massachusetts Institute of Technology in the 1970s. One of these is on display in the Hart Nautical Gallery in MIT. At the same time, AUVs were also developed in the Soviet Union[1] (although this was not commonly known until much later).
[edit] Applications
[edit] Commercial
The oil and gas industry uses AUVs to make detailed maps of the seafloor before they start building subsea infrastructure; pipelines and sub sea completions can be installed in the most cost effective manner with minimum disruption to the environment.
[edit] Military
A typical military mission for an AUV is to map an area to determine if there are any mines, or to monitor a protected area (such as a harbor) for new unidentified objects. AUVs are also employed in anti-submarine warfare, to aid in the detection of manned submarines.
[edit] Research
Scientists use AUVs to study lakes, the ocean, and the ocean floor. A variety of sensors can be affixed to AUVs to measure the concentration of various elements or compounds, the absorption or reflection of light, and the presence of microscopic life.
[edit] Vehicle Designs
Hundreds of different AUVs have been designed over the past 50 or so years[2], but only a few companies sell vehicles in any significant numbers. The small REMUS 100 AUV developed by Woods Hole Oceanographic Institution in the US and now marketed by Hydroid, Inc. is the most popular AUV in the military and scientific markets today. In the oil and gas industry, the larger Norwegian HUGIN 3000 AUV developed by Kongsberg Maritime and Norwegian Defence Research Establishment (FFI) dominates. Other notable AUV manufacturers include Bluefin Robotics in the US and International Submarine Engineering Ltd. in Canada.
Although not currently operational, there are several designs of AUV that are capable of subsea intervention (interaction with subsea structures) as opposed to fly-by data collection. Development of subsea processing in deep and ultra deep offshore oilfields and their cost of maintenance will be the most likely to encourage development of these vehicles.
Today, most AUVs work in conjunction with surface vessels for navigational purposes, although ultra-low-power, long-range variants such as underwater gliders are becoming capable of operating unattended for weeks or months in littoral and open ocean areas, periodically relaying data by satellite to shore, before returning to be picked up.
As of 2008, a new class of AUVs are being developed, which mimic designs found in nature. Although most are currently in their experimental stages, these biomimetic (or bionic) vehicles are able to achieve higher degrees of efficiency in propulsion and maneuverability by copying successful designs in nature. Two such vehicles are Festo's AquaJelly and Evo Logics' Bionik Manta.
[edit] Sensors
Primarily oceanographic tools, AUVs carry sensors to navigate autonomously and map features of the ocean. Typical sensors include compasses, depth sensors, sidescan and other sonars, magnetometers, thermistors and conductivity probes. A demonstration at Monterey Bay in California in September 2006 showed that a 21-inch (530 mm) diameter AUV can tow a 300 feet (91 m) long hydrophone array while maintaining a 3-knot (5.6 km/h) cruising speed.12
[edit] Navigation
AUVs can navigate using an underwater acoustic positioning system. When operating within a net of sea floor deployed baseline transponders; this is known as (LBL) navigation. When a surface reference such as a support ship is available, ultra-short baseline (USBL) or short-baseline (SBL) positioning is used to calculate where the subsea vehicle is relative to the known (GPS) position of the surface craft by means of acoustic range and bearing measurements. When it is operating completely autonomously, the AUV will surface and take its own GPS fix. Between position fixes and for precise maneuvering, an inertial navigation system onboard the AUV measures the acceleration of the vehicle and Doppler velocity technology is used to measure rate of travel. A pressure sensor measures the vertical position. These observations are filtered to determine a final navigation solution.
[edit] Power
Most AUVs in use today are powered by rechargeable batteries (lithium ion, lithium polymer, nickel metal hydride etc). Some vehicles use primary batteries which provide perhaps twice the endurance -- at a substantial extra cost per mission. A few of the larger vehicles are powered by aluminum based semi-fuel cells.
[edit] See also
- Intervention AUV
- Underwater gliders
- Bionics, Biomimetics
- Monterey Bay Aquarium Research Institute
- Office of Naval Research
- National Oceanography Centre, Southampton
- DeepC
- National Institute for Undersea Science and Technology
[edit] References
[edit] External links
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[edit] Collection of groups and projects
- Autonomous Underwater Vehicles
- Saab Seaeye AUV,ROV & Underwater Robotics
- Browseable AUV database at AUVAC.org
- GREX - Scientific research for AUV coordination and control (a project by order of the European Union)
