University professor designs first “tunabot”: Former Langholm pupil examines how fish swim so fast and far

A LEADING American university professor, who attended Langholm Academy, has invented a “tunabot”.
Hilary Bart-Smith, the daughter of Peter and Elizabeth Bart-Smith, was interviewed on the BBC World Service about the project she is doing at the University of Virginia.
After leaving school, Hilary did a degree in mechanical engineering at the University of Glasgow and gained her PhD in engineering sciences at Harvard University.
She joined the mechanical and aerospace engineering faculty of UVA in 2002 and founded the multi-functional materials and structures lab and the bio-inspired engineering research lab.
In August 2015 Hilary received two Multidisciplinary University Research Initiative (MURI) grants from the Department of Defense.
She used nature as her inspiration for developing new, high-performance methods to propel underwater vehicles.
During her first MURI Hilary and her colleagues studied batoid rays which include manta rays and cownose rays.
Their work produced a better understanding of issues affecting their movements through the water, including wake structure, structural dynamics and kinematics.
For the second MURI they chose trout, tuna and dolphin to study. They are fast, efficient swimmers but have differences in their fin structures, mechanical properties and swimming mechanisms, making a group ideal for study.
Bullet-like
In her radio interview Hilary explained they wanted to replicate the bullet-like shape of the tuna with its large body and small tail so they scanned one and created a 3D version.
She said: “It’s an example of a high-speed, high-endurance fish in the ocean. We wanted to understand why it can swim so fast and far.
“They can swim incredibly quickly; some measurements show 75km an hour or 10 body lengths a second.”
The first version of the tunabot did four body lengths a second. The next, at 60 per cent power, did four and a half.
Hilary said: “One challenge we had was to design something which could emulate the fish. They can swim at very high frequencies; the number of times the tail flaps in a second.
“The tunabot could achieve only two beats a second or two hertz.
“Our aim was to implement a system which could push that frequency range up into where the fish are at 20 hertz.
“We designed a system which could take rotary motion from a motor and create a flapping motion. It’s a simple mechanical design. Our tunabot can now get up to 15 beats a second.
“The way we’ve designed it and the design’s robustness enabled us to test the frequency ranges in fish themselves.”
Hilary said she wanted to understand how a fish swam but they didn’t always want to do what you wanted them to when you were studying them.
She wanted to devise a platform which took them away from traditional propeller-driven systems and develop an efficient system which could swim fast and swim far on minimal power.
The tunabot had been swimming in the pool at the university and competing against their swim team to see how well it could compete against them.
Uses the tunabot may have is monitoring the ocean environment and deploying it to monitor infrastructure, like bridges, in places where the environment can be hazardous.
Hilary said: “It would be a system which could swim against the fast currents and monitor structural integrity.”