Tag Archives: autonomous underwater vehicle (AUV)

The Sea Hunter Drone

darpa sea hunter. image from DARPA

The Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) is developing an unmanned vessel optimized to robustly track quiet diesel electric submarines. … capable of missions spanning thousands of kilometers of range and months of endurance under a sparse remote supervisory control model. This includes…autonomous interactions with an intelligent adversary.
Excerpts from Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ASW Continuous Trail Unmanned Vessel (ACTUV))

See also SeaWeb live, DARPA Hydra

The Engineered Seas: artificial reefs

Biorock. Image from wikipedia

Reefs improvised from junk often do not work well. Corals struggle to colonise some metals, and cars and domestic appliances mostly disintegrate in less than a decade. Some organisms do not take to paints, enamels, plastics or rubber. Precious little sea life has attached itself to the 2m or so tyres sunk in the early 1970s to create a reef off Fort Lauderdale, Florida. Tyres occasionally break free, smash into coral on natural reefs and wash ashore.

Yet building artificial reefs that are attractive to marine life can pay dividends. Some of the reefs built in Japanese waters support a biomass of fish that is 20 times greater than similarly sized natural reefs, says Shinya Otake, a marine biologist at Fukui Prefectural University. He expects further gains from a decision by the Japanese government to build new reefs in deep water where they will be bathed in nutrients carried in plankton-rich seawater welling up from below.

The potential bounty was confirmed in a recent study by Occidental College in Los Angeles. Over five to 15 years researchers surveyed marine life in the vicinity of 16 oil and gas rigs off the Californian coast. These were compared with seven natural rocky reefs. The researchers found that the weight of fish supported by each square metre of sea floor was 27 times higher for the rigs. Although much of this increase comes from the rigs providing fish with the equivalent of skyscraper-style living, it suggests that leaving some rigs in place when production ceases might benefit the environment.

Making reefs with hollow concrete modules has been especially successful. Called reef balls, these structures are pierced with holes and range in height up to 2.5 metres. The design is promoted by the Reef Ball Foundation, a non-profit organisation based in Athens, Georgia. Reef balls can be positioned to make the most of photosynthesis and for plankton to drift slowly across their curved inner surface. This improves the nourishment of plants and creatures setting up home within. A hole in the top reduces the chance of them being moved about by storm currents.

Concrete used to make a reef ball is mixed with microsilica, a silicon-dioxide powder, to strengthen the material and lower its acidity level to be more organism-friendly. The balls are cast from fibreglass moulds, which are typically sprayed with a sugary solution before the concrete is poured. This creates tiny hollows which provide a foothold for larval corals. Over 500,000 reef balls have been placed in the waters of more than 60 countries, and each one should last for some 500 years, says the foundation.

The value of artificial reefs has been boosted by the spread of GPS devices and sophisticated sonars on boats. This allows fishermen to locate the subsea structures precisely. It is necessary to be directly above the reef to reel in more fish, says David Walter of Walter Marine, an Alabama company that used to sink vehicles for fishermen but now places pyramid-shaped, hurricane-resistant steel, concrete and limestone structures to create artificial reefs. These constructions can cost nearly $2,000, but many fishermen consider them to be a good investment, especially to catch red snapper.

Using underwater drones for long-term studies of reefs and their associated marine life is also helping improve designs. Sensors can be installed on reefs to monitor boat traffic and activities such as fishing and scuba diving.

Perhaps the most innovative way to build a reef involves anchoring a frame made with steel reinforcing bars to the sea floor and zapping it continuously it with electricity. This causes minerals dissolved in seawater to crystallise on the metal, thickening the structure by several centimetres a year. Biorock, as the resulting material has been trademarked, becomes stronger than concrete but costs less to make. More than 400 “electrified” reefs, many the size of a small garage, have been built this way. Three-quarters of them are in the ocean around Indonesia.

Excerpts, Artificial reefs: Watery dwellings, Economist, Dec.6, 2014,  Technology Quarterly,  at 4

The SeaWeb Live: sound waves, drones and gliders

image from bluefinrobotics.com

UUVs [unmanned underwater vehicles]  will probably play a bigger role as roving wireless nodes that increase the reach of underwater networks. The latest “glider” UUVs consume very little battery power…. Already, gliders serving as “mules” are descending to sensors in deep water where they acoustically collect information. They then ascend to the surface and send the data via radio, says David Kelly, chief executive of Bluefin Robotics, which provides UUVs to half a dozen navies.

The US Navy has ordered several gliders to form underwater mobile networks. With no engine noise, a stealthy “swarm” of gliders could monitor submarines and ships entering a strait, for example, surfacing to transmit their findings. Floating gateway nodes, dropped from the air, allow messages to be sent to submerged devices via low-frequency acoustic signals. This scheme, known as Deep Siren and developed by Raytheon, an American defence contractor, has been tested by the British and American navies.

“Underwater networking will put an end to the ‘data starvation’ experienced by submarines”.  The combination of acoustic signalling and UUVs, which can deliver data physically, will put an end to the “data starvation” experienced by submarines, as America’s submarine command described it in a report last year. Often incommunicado, subs have been condemned to “lone wolf” roles, says Xavier Itard, head of submarine products at DCNS, a French shipbuilder. His firm is developing a funnel-shaped torpedo-tube opening that would make it easier for a UUV to dock with a submarine. Being able to send messages quickly via acoustic networks would enable submarines to take on more tactical roles—inserting special forces when needed to a nearby battlefield, say, or supporting ground operations by launching cruise missiles from the depths.

The Soviet-built ELF radio system remains a “backbone” of Russia’s submarine communications, according to a Norwegian expert. But in a clear vote of confidence in newer technologies, America shut down its own system in 2004. Thanks to steady progress in undersea networks, what was once a technological marvel was, a US Navy statement explained, “no longer necessary”. Whether via sound waves, laser pulses, optical fibres or undersea drones, there are now better ways to deliver data underwater.

Excerpt , Underwater networking: Captain Nemo goes online, Economist Technology Quarterly, Mar. 9, 2013, at 7

Underwater Drones, what’s their secret?

When foreign spies set their sights on America’s secrets, many times they’re not looking underground for secret bunkers or in the sky for massive spy blimps, but under the sea at the nation’s low-profile underwater drone fleet.  “The technology base of the United States is under constant attack,” a new report by the Counterintelligence Directorate of the Pentagon’s Defense Security Service says. “This pervasive and enduring threat is like the weather: ever-present, yet ever changing.”  The maritime drones, which have been stalking the world’s oceans for more than a decade for the U.S. Navy, are capable of a variety of missions including enemy craft and port surveillance, anti-mine operations and even “payload delivery”, according to the Navy.

The DSS report is compiled annually based on incident reports by private U.S. contactors who say they’ve had suspicious contact with a foreign entity that expressed interest in classified technology. The report covers several popular targets for espionage — from U.S. information systems to space technology — but singled out the underwater drones this year as a “special focus area” because it has shown to be a “growing collection area”.  The DSS predicts foreign production of autonomous underwater vehicles (AUV)  to swiftly increase and, along with it, interest in stealing related U.S. technology.

LEE FERRAN, Foreign Spies Target Underwater Drone Fleet, Military Spooks Say, ABC News, Oct. 27, 2011