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Robojelly gets an upgrade: Underwater robot learns to swim more like the real thing

Date:
November 22, 2011
Source:
American Physical Society
Summary:
Engineers 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.
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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.

According to VirginiaTech mechanical engineer Alex Villanueva, Robojelly looks very similar to an actual jellyfish. "Its geometry is copied almost exactly from a moon jellyfish [Aurelia aurita]," he said. The robot is built out of silicone and uses shape memory alloy (SMA) actuators to swim.

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.

"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," said Villanuerva.


Story Source:

The above story is based on materials provided by American Physical Society. Note: Materials may be edited for content and length.


Cite This Page:

American Physical Society. "Robojelly gets an upgrade: Underwater robot learns to swim more like the real thing." ScienceDaily. ScienceDaily, 22 November 2011. <www.sciencedaily.com/releases/2011/11/111122113209.htm>.
American Physical Society. (2011, November 22). Robojelly gets an upgrade: Underwater robot learns to swim more like the real thing. ScienceDaily. Retrieved April 26, 2015 from www.sciencedaily.com/releases/2011/11/111122113209.htm
American Physical Society. "Robojelly gets an upgrade: Underwater robot learns to swim more like the real thing." ScienceDaily. www.sciencedaily.com/releases/2011/11/111122113209.htm (accessed April 26, 2015).

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