Autonomous Underwater Vehicle - AbsoluteAstronomy.com

An autonomous underwater vehicle (AUV) is a robot

Robot

A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...

which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicle

Unmanned underwater vehicle

Unmanned underwater vehicles are any vehicles that are able to operate underwater without a human occupant. These vehicles may be divided into two categories, Remotely operated underwater vehicles , which are controlled by a remote human operator, and Autonomous underwater vehicles , which...

s, a classification that includes non-autonomous remotely operated underwater vehicles (ROVs) – controlled and powered from the surface by an operator/pilot via an umbilical or using remote control. In military applications AUVs more often referred to simply as unmanned undersea vehicles (UUVs).

History

The first AUV was developed at the Applied Physics Laboratory at the University of Washington

University of Washington

University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

as early as 1957 by Stan Murphy, Bob Francois and later on, Terry Ewart. The "Special Purpose Underwater Research Vehicle", or SPURV

SPURV

SPURV, or Special Purpose Underwater Research Vehicle, was an Autonomous Underwater Vehicle built in 1957 at the University of Washington's Applied Physics Laboratory.-Construction:...

, was used to study diffusion, acoustic transmission, and submarine wakes.

Other early AUVs were developed at the Massachusetts Institute of Technology

Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

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

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

(although this was not commonly known until much later).

Applications

Until relatively recently, AUVs have been used for a limited number of tasks dictated by the technology available. With the development of more advanced processing capabilities and high yield power supplies, AUVs are now being used for more and more tasks with roles and missions constantly evolving.

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. The AUV allows survey companies to conduct precise surveys or areas where traditional bathymetric surveys would be less effective or too costly. Also, post-lay pipe surveys are now possible.

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. An example of this is the AN/BLQ-11

Long-Term Mine Reconnaissance System

The AN/BLQ-11 autonomous Unmanned Undersea Vehicle is a torpedo tube-launched and tube-recovered underwater search and survey unmanned undersea vehicle capable of performing autonomous minefield reconnaissance as much as in advance of a host Los Angeles-, Seawolf-, or Virginia-class...

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.

Hobby

Many roboticists construct AUVs as a hobby. Several competitions exist which allow these homemade AUVs to compete against each other while accomplishing objectives. Like their commercial brethren, these AUVs can be fitted with cameras, lights, or sonar. As a consequence of limited resources and inexperience, hobbiest AUVs can rarely compete with commercial models on operational depth, durability, or sophistication. Finally, these hobby AUVs are usually not oceangoing, being operated most of the time in pools or lakebeds. A simple AUV can be constructed from a microcontroller, PVC pressure housing, automatic door lock actuator, syringe

Syringe

A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can be pulled and pushed along inside a cylindrical tube , allowing the syringe to take in and expel a liquid or gas through an orifice at the open end of the tube...

s, and a DPDT relay.

Vehicle designs

Hundreds of different AUVs have been designed over the past 50 or so years, but only a few companies sell vehicles in any significant numbers. There are about 10 companies that sell AUVs on the international market, including Kongsberg Maritime, Hydroid (now owned by Kongsberg), Bluefin Robotics, International Submarine Engineering Ltd. and Hafmynd.

Vehicles range in size from man portable lightweight AUVs to large diameter vehicles of over 10 metres length. Once popular amongst the military and commercial sectors, the smaller vehicles are now losing popularity. It has been widely accepted by commercial organizations that to achieve the ranges and endurances required to optimize the efficiencies of operating AUVs a larger vehicle is required. However, smaller, lightweight and less expensive AUVs are still common as a budget option for universities.

Some manufacturers have benefited from domestic government sponsorship including Bluefin and Kongsberg. The market is effectively split into three areas: scientific (including universities and research agencies), commercial offshore (oil and gas etc.) and military application (mine countermeasures, battle space preparation). The majority of these roles utilize a similar design and operate in a cruise mode. They collect data while following a preplanned route at speeds between 1 and 4 knots.

Commercially available AUVS include various designs such as the small REMUS 100 AUV developed by Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution is a private, nonprofit research and higher education facility dedicated to the study of all aspects of marine science and engineering and to the education of marine researchers. Established in 1930, it is the largest independent oceanographic research...

in the US and now marketed by Hydroid, Inc.; the larger HUGIN 1000 and 3000 AUVs developed by Kongsberg Maritime

Kongsberg Maritime

Kongsberg Maritime is a Norwegian technology enterprise within the Kongsberg Gruppen . Kongsberg Maritime deliver systems for positioning, surveying, navigation and automation to merchant vessels and offshore installations...

and Norwegian Defence Research Establishment

Norwegian Defence Research Establishment

The Norwegian Defence Research Establishment is a research institute that conducts research and development on behalf of the Norwegian Armed Forces and provides expert advice to political and military defence leaders...

; the Bluefin Robotics 12 and 21 in (304.8 and 533.4 mm) vehicles and the International Submarine Engineering Ltd. Explorer. Most AUVs follow the traditional torpedo shape as this is seen as the best compromise between size, usable volume, hydrodynamic efficiency and ease of handling. There are some vehicles that make use of a modular design, enabling components to be changed easily by the operators.

The market is evolving and designs are now following commercial requirements rather than being purely developmental. The next stage is likely to be a hybrid AUV/ROV that is capable of surveys and light intervention tasks. This requires more control and the ability to hover. Again, the market will be driven by financial requirements and the aim to save money and expensive ship time.

Today, while most AUVs are capable of unsupervised missions most operators remain within range of acoustic telemetry systems in order to maintain a close watch on their investment. This is not always possible. For example, Canada has recently taken delivery of two AUVs (ISE Explorers) to survey the sea floor underneath the Arctic ice in support of their claim under Article 76 of the United Nations Convention of the Law of the Sea. Also, 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

Festo

Festo is a German industrial control and automation company based in Esslingen am Neckar, Germany. Festo is an engineering-driven company that sells pneumatic and electric transducers primarily to the automation industry.-History:...

's AquaJelly and Evologics' Bionik Manta.

Sensors

Primarily oceanographic tools, AUVs carry sensors to navigate autonomously and map features of the ocean. Typical sensors include
compass

Compass

A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

es, depth sensors, sidescan and other sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

s, magnetometer

Magnetometer

A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...

s, thermistor

Thermistor

A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor...

s and conductivity probes. A demonstration at Monterey Bay

Monterey Bay

Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....

in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

in September 2006 showed that a 21 inches (533.4 mm) diameter AUV can tow a 400 feet (121.9 m) long hydrophone array while maintaining a 6 knots (11.8 km/h) cruising speed.

Navigation

AUVs can navigate using an underwater acoustic positioning system

Underwater Acoustic Positioning System

An underwater acoustic positioning system is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation...

. When operating within a net of sea floor deployed baseline transponders this is known as LBL navigation

Long Baseline Acoustic Positioning System

A Long Baseline Acoustic Positioning System is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are Ultra Short Baseline Systems and Short Baseline Systems...

. When a surface reference such as a support ship is available, ultra-short baseline

Ultra-short baseline

USBL is a method of underwater acoustic positioning. A complete USBL system consists of a transceiver, which is mounted on a pole under a ship, and a transponder/responder on the seafloor, a towfish, or on a ROV...

(USBL) or short-baseline (SBL)

Short Baseline Acoustic Positioning System

A Short Baseline Acoustic Positioning System is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are Ultra Short Baseline Systems and Long Baseline Systems...

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

Inertial navigation system

An inertial navigation system is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references...

on board 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

Kalman filter

In statistics, the Kalman filter is a mathematical method named after Rudolf E. Kálmán. Its purpose is to use measurements observed over time, containing noise and other inaccuracies, and produce values that tend to be closer to the true values of the measurements and their associated calculated...

to determine a final navigation solution. An emerging alternative is using an inertial navigation system

Inertial navigation system

in conjunction with either a GPS receiver, or an additional magnetic compass for Dead Reckoning

Dead reckoning

In navigation, dead reckoning is the process of calculating one's current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course...

whenever the GPS signal is lost.

Propulsion

AUVs can rely on a number of propulsion techniques, but propeller

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

based thruster

Thruster

A thruster is a small propulsive device used by spacecraft and watercraft for station keeping, attitude control, in the reaction control system, or long duration low thrust acceleration.-Spacecraft thrusters:...

s or Kort nozzle

Kort nozzle

The Kort nozzle is a shrouded, ducted propeller assembly for marine propulsion. The hydrodynamic design of the shroud, which is shaped like a foil, offers advantages for certain conditions over bare propellers....

s are the most common by far. These thrusters are usually powered by electric motors and sometimes rely on a lip seal in order to protect the motor internals from corrosion. One consideration which impacts this process of waterproofing is the decision to use brushed motors or brushless motors. This same consideration also impacts reliability, efficiency, and cost.

Power

Most AUVs in use today are powered by rechargeable batteries (lithium ion, lithium polymer, nickel metal hydride etc), and are implemented with some form of Battery Management System

Battery Management System

A battery management system is any electronic system that manages a rechargeable battery , such as by monitoring its state, calculating secondary data, reporting that data, protecting the battery, controlling its environment, and / or balancing it.-Monitor:A BMS may monitor the state of the...

. 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 cell

Fuel cell

A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...

s, but these require substantial maintenance, require expensive refills and produce waste product that must be handled safely. An emerging trend is to combine different battery and power systems with Ultra-capacitors.

External links

Collection of groups and projects

NOAA, Ocean Explorer AUVfest 2008: What Are AUVs, and Why Do We Use Them?
Autonomous Underwater Vehicles
Prosapien LLC
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
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

)
Ocean Systems Laboratory - Heriot-Watt University, Scotland
First AUV to cross Atlantic Ocean Displayed at Smithsonian
Presentation of the AUV Abyss (IFM-GEOMAR Kiel)

Application papers

The Application of Autonomous Underwater Vehicle (AUV) Technology in the Oil Industry – Vision and Experiences

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