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December 13, 2018

Underwater sensors for monitoring sea life (and where to find them)

Paul Gibbs, a mechanical engineer at the UW’s Applied Physics Laboratory, inspects the newest Adaptable Monitoring Package, or AMP, before a test in a saltwater pool. AMPs host a series of sensors that allow researchers to continuously monitor animals underwater.Kiyomi Taguchi/University of Washington

Harvesting power from the ocean, through spinning underwater turbines or bobbing wave-energy converters, is an emerging frontier in renewable energy.

Researchers have been monitoring how these systems will affect fish and other critters that swim by. But with most available technology, scientists can get only occasional glimpses of what’s going on below.

So a team at the University of Washington created a mechanical eye under the ocean’s surface, called an Adaptable Monitoring Package, or AMP, that could live near renewable-energy sites and use a series of sensors to continuously watch nearby animals. On Dec. 13, the researchers put the newest version of the AMP into the waters of Seattle’s Portage Bay for two weeks of preliminary testing before a more thorough analysis is conducted in Sequim, Washington.

“The big-picture goal of the AMP when it started was to try to collect the environmental data necessary to tell what the risks of marine energy were,” said Brian Polagye, a UW associate professor of mechanical engineering and the director of the Pacific Marine Energy Center, a research collaboration between the UW, Oregon State University and the University of Alaska Fairbanks. “But we ended up with a system that can do so much more. It’s more of an oceanographic Universal Serial Bus. This is a backbone, and you can plug whatever sensors you want into it.”

Paul Gibbs and mechanical engineering doctoral student Emma Cotter watch the newest AMP during a preliminary test in a saltwater pool. Credit: Kiyomi Taguchi/University of Washington

The newest member of the AMP family has the biggest variety of sensors yet, including an echosounder, which uses sonar to detect schools of fish. It also will contain the standard set of instruments that all previous AMPs have supported, including a stereo camera to collect photos and video, a sonar system, hydrophones to hear marine mammal activity and sensors to gauge water quality and speed. This new system also does more processing in real time than its predecessors.

“We want the computer to not just collect data, but actually distinguish what it sees,” said Emma Cotter, a UW doctoral student in mechanical engineering. “For example, we’d like to program it to automatically save images if sea turtles swim by the AMP.”

This new AMP will get its first taste of life outside while hanging off the UW Applied Physics Laboratory‘s research dock. That way, the team can check all the sensors for any potential problems before the AMP goes to the Marine Sciences Laboratory in Sequim for a suite of tests.

“We’re going to be looking at quite a few different questions in Sequim,” Cotter said. “First we’ll look at how well we can track and detect fish. Then once a small tidal turbine is deployed, we’ll be monitoring that. Will we be able to discriminate targets close to it or detect animals interacting with the turbine?”

The wave-powered AMP (top left) after nearly two months of operation at the Wave Energy Test Site in Hawaii.University of Washington

The team also has developed additional AMPs that are more specific to other types of oceanographic research. Since early October, an AMP has been surveying sea life off the coast of Hawaii while riding aboard a yellow metal ring, called the BOLT Lifesaver, through a partnership with the Navy, the U.S. Department of Energy, University of Hawaii and the company Fred. Olsen.

“They were interested in what happens if whales and sea turtles encounter the mooring lines that connect the Lifesaver to the seabed,” Cotter said. “The best way to answer that question is with an AMP.”

The Lifesaver is a wave-energy converter — a device that converts the bobbing of waves into electricity — that powers this AMP. And for the days when the sea is calm, the team powers the AMP from a battery.

“This is the first example of using wave energy to power oceanographic sensors,” Polagye said. “Previously people have collected wave energy and sent it back to shore. But this AMP is completely self-reliant. Marine energy is not just coming in the far future. It’s happening right now.”

A view of fish from the wave-powered AMP’s camera. This AMP is currently collecting data off the coast of Hawaii.University of Washington

The research group is also working on a vessel-based version of the AMP, which will ride aboard APL’s newest research vessel, the R/V Light. The team plans to test tidal turbines on the boat, so the vessel-based AMP will let the researchers see if anything happens to fish that are close by.

Now the team hopes to commercialize the AMP platform through a UW spinout company called MarineSitu. That way people can purchase AMPs with sensor packages that are specific to their research goals.

Other members of the AMP team include Andy Stewart, assistant director of defense and industry programs at APL; Robert Cavagnaro, Paul Gibbs and James Joslin, mechanical engineers at APL; and Paul Murphy and Corey Crisp, research engineers in the UW mechanical engineering department. This research was funded by the Naval Facilities Engineering Command Engineering and Expeditionary Warfare Center and the U.S. DOE Water Power Technologies Office. Emma Cotter is supported by a National Science Foundation Graduate Research Fellowship.

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For more information, contact Polagye at bpolagye@uw.edu.