UBC Reports | Vol. 48 | No. 12 | Oct.
10, 2002
Is That a Fin in the Water?
Robo-ray points the way to better underwater propulsion
By Michelle Cook
Don’t be alarmed if you spot something fishy in the
basement of the Hennings Building. It’s just Robo-Ray,
a robotic fin built by a team of UBC Engineering Physics undergraduates
looking for a better method of underwater propulsion.
Renee Boileau, Lilian Fan and Tim Moore created Robo-Ray
last year. The little electromechanical fin won the Engineering
Physics Dept. prize for top senior project but its potential
to influence future submersible designs is what has really
sparked interest.
“What we were trying to do was find a way to move under-
water that is more efficient than a propeller,” says
Boileau. “The ray fish is flat and skinny and doesn’t
carry a lot of energy but it can move fast. It’s incredibly
powerful and graceful, and we were looking for a way to mechanize
a robot that would swim through the water with similar grace.”
By mimicking the flapping and rippling movements, called
rajiform motion, that rays use to swim, it may be possible
to design more flexible, energy-efficient unmanned submersibles
for use in oil rig inspections, ocean floor surveys and even
wildlife conservation activities, Boileau explains.
The team’s choice of fish stemmed, in part, from a project
done by some Physics students and, in larger part, from Boileau’s
long-time fascination with rays – something she acquired from
watching ocean researcher Jacques Cousteau on television.
Using resources in the Engineering Physics Project lab, Boileau
along with Moore, an aspiring naval architect, and Fan, the
team’s electrical whiz, began experimenting with cables,
motors, gears and pulleys to re-create a fin.
“It got very bulky very quickly because rays have many
bones,” says Boileau, who took a zoological physics course
to help understand a ray’s physiological structure.
The team’s breakthrough came when Fan found an unusual
type of wire while surfing the Web. Called Shape Memory Alloy,
the wire’s properties allow it to contract when heated
– perfect for mimicking the muscles of a swimming ray.
The group fitted a fin-shaped piece of yellow sailcloth with
a series of shape memory wires, and ran electricity through
them in a timed sequence to produce the flapping motion of
a ray on the move.
Robo-Ray was born.
A big challenge was getting the fin to “behave”
by controlling the wires’ shape and their heat up/cool
down rate, says Fan. But the bigger question was: could Robo-Ray
swim?
The team took it to the B.C. Research Inc. 66-metre tow tank
on campus and released it.
It took to water, well, like a fish.
Although the members of Team Robo-Ray all graduated in spring
2002, the trio plans to continue working with current undergraduates
to build a more complex model with better propulsion. As for
Robo-Ray, it’s still lurking somewhere in the depths
of the Hennings Bldg.
