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Posts Tagged ‘autonomous underwater vehicles’

Tethys, designed at the Monterey Bay Aquarium Research Institute, represents a new class of autonomous underwater vehicles. Most AUVs sacrifice range for robust science instruments, or vice versa, leaving scientists with an incomplete picture of life on the seas. Tethys, on the other hand, can travel at high speeds for hundreds of miles, float with the currents for weeks at a time and carry a wide range of instruments.

For most of October, it crisscrossed Monterey Bay as part of an experiment to track microscopic algae patches. It did such a good job that its creators hope to send it to Hawaii eventually, using high-powered disposable batteries.

The robot’s creator, Jim Bellingham, spent four years trying to build an AUV that could bring agility and endurance to the study of oceanography. In the past, studying phenomena like algal blooms depended on luck and timing — oceanographers would stick an instrument on a mooring and hope algae would drift past it, or they would schedule a cruise and hope the bloom would happen while they were at sea, he explains in a MBARI news story.

“Tethys can travel to a spot in the ocean and 'park' there until something interesting happens,” he said. Once a bloom occurs, Tethys can switch into high gear and follow the bloom as it evolves, much like biologists on land would follow migrating animals.

The new robot can make its own decisions, unlike most AUVs, which are programmed to follow a specific path through the water. Tethys can make some decisions without human intervention, much like its cousin 'bot, Gulper.

Tethys can also work in concert with other short-range AUVs, which might have even more science instruments on board. In the recent algae experiment, Tethys would park in an algae patch and pinpoint its center so scientists could send in other robots for more extensive analysis, as Sandeep Ravindran at Nature News explains.

Best of all, it will only cost a bit more than the average glider, which runs about $140,000. It’s cheap enough that individual labs can buy them, Bellingham said.

As Technology Review reports, divers can use symbols on tablet computers to control underwater 'bots. The system could enable enhanced diver/robot collaboration.

Despite their importance for aquaculture, surveillance and oil-spill cleanup, it's still difficult to remotely control robots underwater, especially when they are not tethered to a mother ship. Radio waves are too easily distorted, sonar requires too much power, and aquatic particles interfere with light waves. One new system would give robots transmission capabilities, allowing them to relay information and work in swarms.

The waterproof tablets may be the solution. They can display two-dimensional bar codes, or tags, that are already in use for smart phone applications. The tag at left is showing 10 bits.

Flashing the tags at a free-swimming AQUA robot's underwater camera allows for fast, robust communication. It's better than other untethered communication platforms like sonar, Tech Review reports.

The tags correspond to a command stored in the robot's memory. When the bot is tethered, it can react to the tags instantly and transmit video back to the tablet. When it's untethered, it can respond to a tag command, perform its task and report back to the diver.

To date, the system has been tested in the open ocean and in swimming pools. Possible future uses include studying shipwrecks or even military applications, Tech Review says.

[Technology Review]

The European Union-funded Grex project, named for the Latin word for "flock," involves networking software to coordinate multiple autonomous underwater vehicles, or AUVs. Multiple AUVs can benefit from the sum of their parts, as the project's Web site notes -- each could perform separate functions that contribute to a larger mission.

Until now, AUVs have operated solo, partly because it's difficult to link different vehicles through seawater at distances of more than a few hundred feet. But in the Grex system, vehicles will be able to act as relay stations, bouncing a control signal from the mother ship to the networked submarines over many miles.

One of the firms involved in the Grex project, German firm MC Marketing Consulting, designed a "Grex box" that incorporates communications tied to the vehicle controls. The system could be added to an existing AUV, retrofitting it for use as a team member, according to Michael Jarowinsky of MC Marketing Consulting.

In tests off the coast of Portugal last winter, Grex-capable vehicles were able to assemble into formation and perform "swarm" tasks. Two small boats and two AUVs each ran its own tack while talking to the others and adjusting its speed to reach formation.

The main goal is to use Grex vehicles for marine science -- as the group points out, humans know more about the surface of the moon than we do about the oceans, 90 percent of which has not been explored. But the technology has several commercial applications, including the offshore oil industry, Jarowinsky says.

SeeByte, one of the project's partners, plans to market the control software and graphical user interface for managing schools of AUVs. The project coordinator, ATLAS Elektronik, plans within the next four years to offer a complete system, including the Grex box, software and installation and training.

[PhysOrg]