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Improving Efficiency for Autonomous Underwater Vehicles

08 November 2022

Recent PhD graduate Michael Coe advances research into Autonomous Underwater Vehicles


PhD graduate Michael Coe demonstrating robotic fish with Supervisor Ass. Prof. Stefanie Gutschmidt

The UC Mechanical Engineering Department is pleased to announce and highlight recent PhD graduate Michael Coe for his successful thesis submission and defense titled, "Intersection between natural and artificial swimmers: a scaling approach to underwater vehicle design."

PhD student Michael Coe supervised by Stefanie Gutschmidt PhD graduate Michael Coe

The lifecycle of a PhD is often described as a stressful yet rewarding experience, requiring a tremendous amount of dedication and perseverance. We were fortunate to get in touch with Michael to gain a little perspective on his contributions to the field and some impressions of his trial and culminating success over the past few years.

“My research dives into the design of Autonomous Underwater Vehicles. I gathered and compared over 300 underwater vehicles using a system integration point of view. This means that I had to consider things like the payload, locomotion mode, and method of actuation. The goal of the research was to develop scaling laws that can give you an estimate of the power consumption, speed, and cost of an underwater vehicle at any size. For vehicles that I didn’t have data for, like the power consumed by fish-inspired locomotion modes, I used computational fluid dynamics to develop the laws. What I found was that current propellor driven underwater vehicles are as efficient, if not more efficient, than even biological swimmers (fish and mammals). I also developed a new dimensionless number that allows for the estimation of physical design (propeller size, speed of propeller actuation) and the size of the underwater vehicle,” Michael says.

As a PhD requires such a level of commitment, it can be helpful to frame what motivates an individual to undertake such an enterprise.

“There has been a push as of late to become a multi-planet species. Generally, the reasoning for this is that it will help us stave off the effects of climate change. I think that it is more likely for humans to colonize the oceans rather than Mars. The issue with this is that humans have only mapped about 20% of the ocean. One of the tools we use for ocean exploration is Autonomous Underwater Vehicles. These vehicles are limited because they need to have all the energy for a mission onboard. My research seeks to identify the major consumers of this onboard power and help design a more efficient underwater vehicle.” 

No PhD reaches the finish line without some hurdles to overcome, as anyone who has endeavored such a feat would tell you. For Michael, the main challenge with his work was obtaining accurate data. 

“With conventional Autonomous Underwater Vehicles, the manufacturer doesn’t include an energy consumption metric. A lot of the time you need to find other ways to calculate this. Another challenge was how to model fish motion and perform Computational Fluid Dynamics on a mesh that is undulating during the simulation,” he says.

With the thesis submission and defense in the rearview mirror, Michael now focuses his energy and attention on new ventures.

“I am currently undergoing postdoctoral research in the Department of Chemical and Process Engineering. In the future, I want to research micro scale generators such as thermopiles or bioreactors. The idea behind this would be to allow vehicles to generate energy while on a mission in order to extend their mission times. My goal is to be able to extend this to electric vehicles. Picture an electric vehicle that charges itself all the time and more so when stopped. In the night, the charge can be transferred to the house.” 

Michael certainly has a bright future and career ahead, and we look forward to reporting on the advancements that will be made in the coming years. Congratulations again, Michael!

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