From University of Washington College of Engineering: “Lessons in the deep” Trevor Harrison

From University of Washington College of Engineering

College of Engineering

4.7.21 [Presented today in social media.]

Last updated November 4, 2019

Story by Andy Freeberg
Lead photography by Mark Stone
Other images and videos courtesy of Trevor Harrison and UW µFloat team members.

One student’s journey to build a swarm of robotic devices for underwater mapping.

The path to Trevor Harrison’s Ph.D. reached its climax in the rushing waters of Agate Pass, a narrow tidal strait northwest of Seattle. There the strong flowing currents provided the greatest test yet for a swarm of robotic sensor packages he’s developed to make 3D maps of dynamic underwater environments.

He calls his inventions µFloats (pronounced “microFloat” using the scientific prefix of the Greek letter mu).

The floats are cylinders, roughly two feet long and 11 pounds each, built to do three things: adjust their buoyancy to dive to certain depths, drift with the currents, and gather data such as water speed and temperature from the environment around them. Getting quality data of this kind is currently difficult and costly for researchers who need to understand the characteristics of a particular location, such as for estimating the potential power production and environmental impacts of a tidal energy project.

Now, five years after his first prototype hit the water, Harrison has validated the µFloats as a new technology for surveying tidal flows and coastal environments. But the path was not always straightforward.

1
2
3
[3] ME doctoral student Trevor Harrison runs a test of his µFloat (pronounced “microFloat”) in the UW Ocean Sciences test tank with the assistance of two divers.

From physics to marine energy

Harrison’s undergraduate degree is in physics but while working as a research technician at the Woods Hole Oceanographic Institution (US) he decided to switch to engineering.

“I saw scientists building cool oceanographic instrumentation and was captivated,” he recalls. “I knew I wanted to go back to school to do something that felt more tangible, so I was looking for areas with a societal and sustainability impact.”

He decided marine renewable energy fit his aspirations and joined ME associate professor Brian Polagye’s lab as a graduate student in 2013.

There, he learned about the need for better maps of tidal and river environments to help determine the best places to put renewable energy systems like tidal power plants or in-river turbines. Tim Mundon, Vice President of Engineering at Oscilla Power and an affiliate faculty member in ME, proposed the idea to Polagye that a swarm of low-cost, free-floating sensors could be a way to improve resource maps. These are critical because even a small difference in the estimated speed of the currents means a large difference in how much electricity a site can potentially generate.

“I took the idea and ran simulations that indicated that if you could put 20 to 50 sensors into the water, that’d be enough to generate a reasonably good 3D map,” says Harrison.

µFloat 1.0: The buoyancy engine

For the initial prototype he challenged a capstone team of Formula Motorsports students to develop a “buoyancy engine” – a device that can adjust whether it sinks or floats.

The team hand-built a hollow tube with a large piston attached to a motor and a basic computer. As the piston moved into the device, it became dense and sunk, as it moved out again, it created a hollow cavity and floated back to the surface.

3
The design of the µFloat developed over three versions between 2016 and 2018.


On May 26, 2016, ME Formula Motorsports students Olivia Rogers, Adam Hill, Alex Reid, James Lindsay demonstrated the very first successful test of a custom-built buoyancy engine device, the earliest µFloat prototype.

µFloat 2.0: A prototype down under

In 2017, Harrison received support from the National Science Foundation’s Graduate Research Opportunities Worldwide program to do cooperative research in Australia with Matthew Dunbabin, a professor of electrical engineering and robotics at the Queensland University of Technology (AU) (QUT).

“I flew to Australia with a half-built float,” he remembers. “I had the buoyancy engine, but I still had to put together the full package of sensors and controls and build out a communication system.”

5
A µFloat schematic.

Over seven months, he prototyped the electronics, testing as he went in QUT’s swimming pool. Two days before his flight back to the U.S., Harrison and Dunbabin took a rented canoe out on the Maroochy River and tossed in the prototype µFloat. After a few tense minutes where they feared the float was lost, they located it, successfully completing the first field test.


µFloat 2.0: A prototype down under.

µFloat 3.0: Assembling a swarm

Back in Seattle, the progress was enough for teammates from the Pacific Marine Energy Center (PMEC) and UW Applied Physics Laboratory (APL) to secure funding from the Office of Naval Research to build a µFloat fleet.

“You learn a lot from building things, and even more from breaking them and re-building them,” says Harrison. “However, I found out that if you build 25 you’d better be ready to learn a ton because something different seems to go wrong on each one.”

6
The fleet of µFloats during the assembly process.

Deploy, recover, debug, repeat.


µFloat Deployment Montage

Following each outing, the µFloat data improved, building the team’s confidence towards the key deployment at Agate Pass. There they would collect data from the µFloat swarm while Jim Thomson, an oceanographer at APL and civil and environmental engineering professor, gathered data in more traditional ways. A comparison between the two surveys would indicate how accurate and effective the uFloats are in practice.

Over the course of two days at Agate Pass, the team repeatedly deployed and retrieved the floats, amassing 340 drifting paths of tidal flow observations. One of the 20 µFloats went missing, but Harrison got a hefty dataset for the last chapter of his dissertation. As far as he’s concerned, the trip was a success.

7
How the µFloats work. Credit: Trevor Harrison.

Having defended his Ph.D., Harrison will continue to explore µFloat applications with APL and through MarineSitu, a marine instrumentation company spun out of the UW.

He credits teamwork for every step of his journey.

“A lot of life happens in eight years. I benefited so much from the amazing people and facilities at the UW. I never would have gotten to this point without a ton of collaboration and support.”

8
ME doctoral student Trevor Harrison returns to campus following a successful trip to Agate Pass to gather data for his Ph.D.

Reference:

Comparative evaluation of volumetric current measurements in a tidally-dominated, coastal setting: a virtual field experiment
Journal of Atmospheric and Oceanic Technology

See the full article here .


five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

About the U Washington College of Engineering

Mission, Facts, and Stats

Our mission is to develop outstanding engineers and ideas that change the world.

Faculty:
275 faculty (25.2% women)
Achievements:

128 NSF Young Investigator/Early Career Awards since 1984
32 Sloan Foundation Research Awards
2 MacArthur Foundation Fellows (2007 and 2011)

A national leader in educating engineers, each year the College turns out new discoveries, inventions and top-flight graduates, all contributing to the strength of our economy and the vitality of our community.

Engineering innovation

Engineers drive the innovation economy and are vital to solving society’s most challenging problems. The College of Engineering is a key part of a world-class research university in a thriving hub of aerospace, biotechnology, global health and information technology innovation. Over 50% of UW startups in FY18 came from the College of Engineering.
Commitment to diversity and access

The College of Engineering is committed to developing and supporting a diverse student body and faculty that reflect and elevate the populations we serve. We are a national leader in women in engineering; 25.5% of our faculty are women compared to 17.4% nationally. We offer a robust set of diversity programs for students and faculty.
Research and commercialization

The University of Washington is an engine of economic growth, today ranked third in the nation for the number of startups launched each year, with 65 companies having been started in the last five years alone by UW students and faculty, or with technology developed here. The College of Engineering is a key contributor to these innovations, and engineering faculty, students or technology are behind half of all UW startups. In FY19, UW received $1.58 billion in total research awards from federal and nonfederal sources.

u-washington-campus
The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.