Fast swimming fish robot could perform underwater surveillance

A tuna-inspired robot can wriggle just as fast as real fish and swim faster than most other robots of its type. This “Tunabot” could help us learn how fish use their fins and may someday be used for underwater surveillance.

Hilary Bart-Smith at the University of Virginia and her colleagues built Tunabot from 3D-printed steel and resin, covered in stretchy plastic skin. It is designed to mimic an adolescent tuna, but without any fins other than the tail, and is about 25 centimetres long.

The team chose to model the robot after a tuna because the fish can swim extremely fast with high energy efficiency. They swim by wiggling their whole bodies back and forth up to about 10 times per second – the faster they thrash, the faster they swim.

Tunabot can wiggle back and forth up to 15 times per second and swim at about 1 metre per second, not quite as fast as tuna but far faster than most other swimming robots. Making Tunabot more similar to actual tuna could help us learn how the tuna themselves swim, says Bart-Smith.

“There’s still a lot to learn in terms of the roles of the different appendages on the tuna itself, like the fins that the robot doesn’t have,” she says.

Bart-Smith and her team are working on adding sensors to Tunabot so that it can be used as a sort of swimming surveillance system, both to monitor things like the structural integrity of ship hulls and bridge supports and possibly to keep an eye out for more nefarious goings-on underwater.

“They can swim for a long time, very slowly monitoring what’s going on and then if necessary swim very fast if they see something that’s interesting to them,” says Bart-Smith. That could make Tunabot an excellent underwater spy.