Engineers hoping to surpass biology and build something that swims father than anything else already out in the ocean are one step closer to achieving their goal with a new robotic fish that can go as fast as live yellowfin tuna.
Mechanical engineers at the University of Virginia School of Engineering, leading a collaboration with biologists from Harvard University, have created the first robotic fish proven to mimic the speed and movements of live yellowfin tuna.
“Tuna robotics: a high-frequency experimental platform exploring the performance space of swimming fishes,” was published Sept. 18, 2019, in Science Robotics, an offshoot of SCIENCE magazine devoted to technological advancements in robotic science and engineering.
Multi-disciplinary study with US Navy
The robotic tuna project was born out of a five-year, $7.2 million Multi-disciplinary University Research Initiative the U.S. Office of Naval Research awarded Bart-Smith to study fast, efficient swimming of different fishes. The aim of Professor Hillary Bart-Smith’s project is to better understand the physics of fish propulsion, research that could eventually inform development of the next generation of underwater vehicles, driven by fish-like systems better than propellers.
Underwater robots also are useful in a range of applications, such as defense, marine resources exploration, infrastructure inspection and recreation.
Could one day have public, commercial uses
Well before bio-inspired propulsion systems can become viable for public and commercial use in manned and unmanned vehicles, however, researchers must be able to reliably understand how fish and other creatures move through water.
“Our goal wasn’t just to build a robot. We really wanted to understand the science of biological swimming,” Bart-Smith said. “Our aim was to build something that we could test hypotheses on in terms of what makes biological swimmers so fast and efficient.”
The team first needed to study the biological mechanics of high-performance swimmers. Harvard biology professor George V. Lauder and his team of researchers precisely measured the swimming dynamics of yellowfin tuna and mackerel.
Robot fish can beat its tail as fast as real fish
Using that data, Bart-Smith and her team, research scientist Jianzhong “Joe” Zhu and Ph.D. student Carl White, constructed a robot that not only moved like a fish underwater but beat its tail fast enough to reach nearly equivalent speeds.
They then compared the robot they named “Tunabot” with live specimens.
“There are lot of papers on fish robots, but most of them don’t have much biological data in them. So I think this paper is unique in the quality of both the robotic work and the biological data married together into one paper,” Lauder said.
The tests of Tunabot take place in a large lab in the Mechanical Engineering building at UVA Engineering, in a flow tank that takes up about a quarter of the room, and at Harvard University in a similar facility.
The eyeless, finless replica fish is roughly 10 inches long; the biological equivalent can get up to seven feet long.
The relationship between biology and robotics is circular, Lauder said. Each discovery in one branch informs the other, a type of educational feedback loop that is constantly advancing both the science and the engineering.
“We don’t assume that biology has evolved to the best solution,” Bart-Smith said. “These fishes have had a long time to evolve to a solution that enables them to survive, specifically, to eat, reproduce and not be eaten.”
When scientists are unconstrained by these requirements, they can focus solely on mechanisms and features that promote higher performance, higher speed, higher efficiency.
Our ultimate goal is to surpass biology. How can we build something that looks like biology but swims faster than anything you see out there in the ocean?”