Quirks and Quarks

Imitating a swift-swimming fish helps researchers build a speedy 'tunabot'

The tunabot can swim four body lengths per second, making it one of the fastest bio-inspired underwater robots.

One secret to tuna-like swimming was a fast-flapping tail

The 'tunabot' modeled after an adolescent yellowfin tuna can flap its tail fin up to 15 times per second, nearly as fast as the real tuna, to propel it through water. (Christopher Tyree)

A team of researchers in the US has designed an underwater 'tunabot,' modelled after the speedy yellowfin tuna, a creature that can hit 75km/h in it's pursuit of underwater prey. 

The team analyzed how the tuna is able to swim so fast and efficiently and found that could flap its tail at an astonishing 25 times per second. They then designed a motor system to flap their tunabot's tail fin nearly as fast, according to engineer Hilary Bart-Smith, who led the research.

The robot is made from 3D-printed steel and resin covered in a stretchy plastic skin. The head is kept rigid and holds the motor that drives the flapping motion of the tail, while the rear part of it's body is flexible to enable movement. 

They tested the robot in a flow tunnel — the water equivalent of a wind tunnel — and found it not only moved like tuna in the water, but due to the fast beating tail was able to reach nearly equivalent speeds and efficiency. 

Creating a propulsion system modelled after the yellowfin tuna one day could lead to faster and more efficient underwater vehicles with applications ranging from defence, to wildlife research, marine resource exploration and infrastructure inspection.