Source: Haibo DongEngineers from the University of Virginia (UVA) School of Engineering, in collaboration with biologists from Harvard University, have developed what they are calling the first-ever robotic fish to mirror the movements and speed of a live yellowfin tuna.

To create the bio-inspired robotic fish, dubbed TunaBot, researchers first investigated how fish and other underwater creatures travel through water, in an effort to better grasp the science of biological swimming and what factors enable fast, efficient swimming. As such, the Harvard team studied the biological mechanics of high-performance swimmers such as yellowfin tuna and mackerel, precisely measuring their swimming dynamic. That information was then relayed to the University of Virginia team and it was used to inform the design of the TunaBot.

The completed TunaBot is approximately 10 in long and features a fishing line tether that steadies the robot as its tail propels. Meanwhile, a green laser shines on the midsection of the robotic fish, measuring the fluid motion emitted by the robot with each motion of its artificial tail. As water current in a UVA lab flow tank speeds up, the TunaBot's tail and entire body move in a quick bending gesture, mimicking how a yellowfin tuna swims.

The purpose of the years-long development of TunaBot was to help the team to better understand the physics behind fish propulsion, eventually applying those principles to the creation of a new generation of underwater vehicles powered by systems inspired by the movement of fish and not propellers.

Improvements to such underwater vehicles could have applications for defense, infrastructure inspection, recreation and marine resource exploration, among others.

"What is so fantastic with the results we are presenting in the paper are the similarities between biology and the robotic platform, not just in terms of the swimming kinematics, but also in terms of the relationship between speed and tail-beat frequency and energy performance," said research lead Hilary Bart-Smith, professor in UVA Engineering's Department of Mechanical and Aerospace Engineering. "These comparisons give us confidence in our platform and its ability to help us understand more about the physics of biological swimming."

"Tuna robotics: a high-frequency experimental platform exploring the performance space of swimming fishes," appears in the journal Science Robotics.