Virginia
Tech College of Engineering researchers have unveiled a life-like, autonomous
robotic jellyfish the size and weight of a grown man, 5 foot 7 inches
in length and weighing 170 pounds. The prototype robot, nicknamed Cyro,
is a larger model of a robotic jellyfish the same team – headed
by Shashank Priya of Blacksburg, Va., and professor of mechanical engineering
at Virginia Tech – unveiled in 2012. The earlier robot, dubbed
RoboJelly, is roughly the size of a man’s hand, and typical of
jellyfish found along beaches. |
“A
larger vehicle will allow for more payload, longer duration and longer
range of operation,” said Alex Villanueva of St-Jacques, New-Brunswick,
Canada, and a doctoral student in mechanical engineering working under
Priya. “Biological and engineering results show that larger vehicles
have a lower cost of transport, which is a metric used to determine
how much energy is spent for traveling.”
Both robots are part of a multi-university, nationwide $5 million project
funded by U.S. Naval Undersea Warfare Center and the Office of Naval
Research. The goal is to place self-powering, autonomous machines in
waters for the purposes of surveillance and monitoring the environment,
in addition to other uses such as studying aquatic life, mapping ocean
floors, and monitoring ocean currents. |
Jellyfish
are attractive candidates to mimic because of their ability to consume
little energy owing to a lower metabolic rate than other marine species.
Additionally, they appear in wide variety of sizes, shapes and colors,
allowing for several designs. They also inhabit every major oceanic
area of the world and are capable of withstanding a wide range of temperatures
in both fresh and salt waters. Most species are found in shallow coastal
waters, but some have been found in depths 7,000 meters below sea level.
Partner universities in the project are Providence College in Rhode
Island, the University of California Los Angeles, the University of
Texas at Dallas, and Stanford University. Priya’s team is building
the jellyfish body models, integrating fluid mechanics and developing
control systems.
Cyro is modeled and named after the jellyfish cyanea capillata, Latin
for Llion’s Manemain jellyfishJellyfish, with “Cyro”
derived from “cyanea” and “robot.” As with its
predecessor, this robot is in the prototype stage, years away from use
in waters. A new prototype model already is under construction at Virginia
Tech’s Durham Hall, where Priya’s Center for Energy Harvesting
Materials and Systems is based.
“We hope to improve on this robot and reduce power consumption
and improve swimming performance as well as better mimic the morphology
of the natural jellyfish,” Villanueva said, adding that the project
also allows researchers such as himself to better understand aquatic
creatures live. “Our hopes for Cyro’s future is that it
will help understand how the propulsion mechanism of such animal scales
with size.”
A stark difference exists between the larger and smaller robots. Cyro
is powered by a rechargeable nickel metal hydride battery, whereas the
smaller models were tethered, Priya said. Experiments have also been
conducted on powering jellyfish with hydrogen but there is still much
research to be done in that area.
In both cases, the jellyfish must operate on their own for months or
longer at a time as engineers likely won’t be able to capture
and repair the robots, or replace power sources.
“Cyro showed its ability to swim autonomously while maintaining
a similar physical appearance and kinematics as the natural species,”
Priya said, adding that the robot is simultaneously able to collect,
store, analyze, and communicate sensory data. This autonomous operation
in shallow water conditions is already a big step towards demonstrating
the use of these creatures.”
How does the robot swim? Its body consists of a rigid support structure
with direct current electric motors which control the mechanical arms
that are used in conjunction with an artificial mesoglea, or jelly-based
pulp of the fish’s body, creating hydrodynamic movement.
With no central nervous system, jellyfish instead use a diffused nerve
net to control movement and can complete complex functions. A parallel
study on a bio-inspired control system is in progress which will eventually
replace the current simplified controller.
As with the smaller models, Cyro’s skin is comprised of a thick
layer of silicone, squishy in one’s hand. It mimics the sleek
jellyfish skin and is placed over a bowl-shaped device containing the
electronic guts of the robot. When moving, the skin floats and moves
with the robot, looking weirdly alive.
“It has been a great experience to finally realize the biomimetic
and bio-inspired robotic vehicles,” Priya said. “Nature
has too many secrets and we were able to find some of them but many
still remain. We hope to find a mechanism to continue on this journey
and resolve the remaining puzzles.”
From: Virginia Tech |
