Engineers
at Virginia Polytechnic Institute and State University (VirginiaTech)
have developed a robot that mimics the graceful motions of jellyfish
so precisely that it has been named Robojelly. Developed for the U.S.
Office of Naval Research in 2009, this vehicle was designed to
conduct ocean underwater surveillance, enabling it potentially to
detect chemical spills, monitor the presence of ships and submarines,
and observe the migration of schools of fish.
Recently,
a team at VirginiaTech has improved the performance of this silicone
swimmer, enabling it to better overcome the limitations of its
artificial skin and better mimic the true motion of a jellyfish.
Details on this new design and how it might provide new insights into
jellyfish propulsion mechanisms are being presented at the 2011
meeting of the American Physical Society's Division of Fluid Dynamics
in Baltimore, Md., Nov. 20-22.
Alex
Villanueva
Mechanical
Engineer
Virginiatech
![Alex Villanueva Mechanical Engineer Virginiatech “Robojelly looks very similar to an actual jellyfish. Its geometry is copied almost exactly from a moon jellyfish [Aurelia aurita]. The robot is built out of silicone and uses shape memory alloy (SMA) actuators to swim. These results clearly demonstrate that the flap plays an important role in the propulsion mechanism of Robojelly and provides an anatomical understanding of natural jellyfish."](../../WATERWAYS%20PEOPLE/021211%20Alex%20Villanueva.jpg "Alex Villanueva Mechanical Engineer Virginiatech “Robojelly looks very similar to an actual jellyfish. Its geometry is copied almost exactly from a moon jellyfish [Aurelia aurita]. The robot is built out of silicone and uses shape memory alloy (SMA) actuators to swim. These results clearly demonstrate that the flap plays an important role in the propulsion mechanism of Robojelly and provides an anatomical understanding of natural jellyfish.\"") "Robojelly
looks very similar to an actual jellyfish. Its geometry is copied
almost exactly from a moon jellyfish [Aurelia aurita]. The robot is
built out of silicone and uses shape memory alloy (SMA) actuators to
swim. These results clearly demonstrate that the flap plays an
important role in the propulsion mechanism of Robojelly and provides
an anatomical understanding of natural jellyfish."
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To
move through the water, the natural animal uses the bell section of
its body, which deforms and contracts to provide thrust. The lower,
or lagging, section of the bell is known as the flexible margin, and
it deforms slightly later in the swimming process than the rest of
the bell. Until recently, however, Robojelly lacked this crucial
piece of anatomy in its design.
Villanueva
and his colleagues tested a number of different designs for their
robot, some with and without an analog to a flexible margin.
Initially, the artificial materials used in construction presented a
problem. Unlike their natural counterparts the artificial materials
tended to fold as they deformed, reducing Robojelly's performance.
After testing a number of designs and lengths for the folding margin,
the engineers discovered that cutting slots into the bell reduced
this unwanted folding effect.
This
gave Robojelly a truer swimming stroke, as well as a big boost in
speed.
Source: American
Physical Society
ROBOJELLY: UNDERWATER ROBOT LEARNS TO SWIM LIKE THE REAL THING - WATERWAYS NEWS - 04 DECEMBER 2011
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