Can robotic submarines collect specimens at any ocean depth?

Yes, they can — and soon they will do a lot more…

By Sarah Jensen

“The ocean is trying to crush everything,” says Franz Hover, an associate professor of mechanical and ocean engineering. “Every 10 meters you go down, you’re adding one atmosphere.” That means the pressure increases until at the lowest spot in the Earth’s oceans — the 11,000-meter-deep Marianas Trench — it reaches 15,750 pounds per square inch, over a thousand times that at sea level.

“Preparing a vehicle to go to such depths is a serious investment,” says Hover. “Not only in terms of the vehicle, but simply getting to these remote places and creating the devices that grab samples.” Submersible systems must be constructed of highly specialized components in order to remain intact and functional, such as metal frames, buoyancy foam, connectors, and housings, and carry state-of-the-art computers, cameras, and navigation systems. But once everything is in place, performing underwater tasks is a relative walk on the beach. “Ocean depth actually has little effect on the operation of remotely operated vehicles,” says Hover. Not sure the community would agree with the last two sentences, and I’d be more comfortable with deleting them — the main message I think is that the vehicle construction, and the critical systems they rely on, are a fundamental level of investment and effort.

Remotely-operated-vehicles (ROVs) are hard at work right now in every ocean. Their robotic manipulators are drilling rock samples, collecting coral, photographing marine life, and deploying sensor packages for the oil and gas industries. ROVs receive their work orders via fiber optic cables enclosed in a tether that extends to the surface. “From the safety of a ship or lab, a human can monitor and drive the vehicle and press buttons to control the robot’s grabbers and samplers and other technology,” explains Hover.

Hover’s research involves the development of smart subs that can make decisions and perform appropriate tasks all on their own. He’s developed a control system now used in ship hull inspection that can monitor such things as levels of biofouling and corrosion of underwater anodes. “There is a lot of important data about the bottom of a boat that you can’t really get unless you put a diver in,” says Hover. “But that comes at a high cost. Autonomous robots are a safer and more economical way to get that information.”

The next frontier? Getting underwater robots to talk to each other and work as a team. Vehicles engaged in group missions could exchange information as they track sharks or coordinate their explorations through optical or acoustic communication. “Optically, they can send megabits per second through 100 meters of clear water,” says Hover. “That’s a lot of data.” Acoustic devices would enable robots to ping one another with important communiqués across 10 kilometers or farther.

Ultimately, Hover believes, autonomous robots could change the face of underwater operations and make them safer and more economical. In particular, he points to the work involved with decommissioning oil rigs in the Gulf of Mexico. It’s a treacherous job site littered with rigs toppled by hurricanes, unstable overhead pipes and cables, and the pollution threat of oil, heavy metals, and natural gas. Currently, divers spend up to 30 days at a stretch dismantling the rigs at depths of up to 1,000 feet. “It’s a dangerous place, and it’s expensive to do it that way,” says Hover. “There’s a great opportunity to do this work with autonomous agents.”

That’s good news for students who are undecided about where to focus their interest in engineering. “Ocean engineering is a fairly small community,” says Hover. “There are a lot of great opportunities for innovations in these autonomous vehicles, as well as in sensors, underwater communication, and fluid mechanics. People can still make a big difference in the field.”

Thanks to Jeff Cassidy Cleveland, Ohio, for this question.

Posted: February 19, 2013

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