Featured Research

from universities, journals, and other organizations

Engineers Are Building Robotic Fin For Submarines

Date:
July 31, 2007
Source:
Massachusetts Institute of Technology
Summary:
Inspired by the efficient swimming motion of the bluegill sunfish, researchers are building a mechanical fin that could one day propel robotic submarines. The researchers chose to copy the bluegill sunfish because of its distinctive swimming motion, which results in a constant forward thrust with no backward drag. In contrast, a human performing the breaststroke inevitably experiences drag during the recovery phase of the stroke.

A bluegill sunfish swims in an MIT laboratory tank near a prototype of a robotic fin designed with the fish's fin as a guide.
Credit: Donna Coveney

Inspired by the efficient swimming motion of the bluegill sunfish, MIT researchers are building a mechanical fin that could one day propel robotic submarines.

Related Articles


The propeller-driven submarines, or autonomous underwater vehicles (AUVs), currently perform a variety of functions, from mapping the ocean floor to surveying shipwrecks. But the MIT team hopes to create a more maneuverable, propeller-less underwater robot better suited for military tasks such as sweeping mines and inspecting harbors--and for that they are hoping to mimic the action of the bluegill sunfish.

"If we could produce AUVs that can hover and turn and store energy and do all the things a fish does, they'll be much better than the remotely operated vehicles we have now," said James Tangorra, an MIT postdoctoral associate working on the project.

The researchers chose to copy the bluegill sunfish because of its distinctive swimming motion, which results in a constant forward thrust with no backward drag. In contrast, a human performing the breaststroke inevitably experiences drag during the recovery phase of the stroke.

Tangorra and others in the Bio-Instrumentation Systems Laboratory, led by Professor Ian Hunter of the Department of Mechanical Engineering, have broken down the fin movement of the bluegill sunfish into 19 components and analyzed which ones are critical to achieving the fish's powerful forward thrust.

"We don't want to replicate exactly what nature does," said Tangorra, who will soon be joining the faculty of Drexel University. "We want to figure out what parts are important for propulsion and copy those."

So far, the team has built several prototypes that successfully mimic the sunfish fin. They reported the successful testing of their most recent fin, which is made of a cutting-edge polymer that conducts electricity, in the June issue of the Bioinspiration & Biomimetics journal.

The latest fin is made of a thin, flexible material that conducts electricity. The fin is able to replicate two motions that the researchers identified as critical to the propulsion of the sunfish fin: the forward sweep of the fins and the simultaneous cupping of the upper and lower edges of the fin.

When an electric current is run across the base of the fin, it sweeps forward, just like a sunfish fin. By changing the direction of the electric current, the researchers can make the fin curl forward at the upper and lower edges, but it has been a challenge to make the fin sweep and curl at the same time. Strategically placing Mylar strips along the fins to restrict their movement to the desired direction has proven successful, but the team continues to seek alternative solutions.

Their first-generation fin successfully replicated the sweeping and cupping motions of the sunfish fin, but the motors that controlled the fin were too large and noisy for use in an AUV. The researchers' new approach, using the new conducting polymer, could eliminate the need for electric motors. The material can be assembled from a solution of chemicals, giving the designers more control over its molecular structure.

"This gives us the potential to build machines or robots in a manner closer to how nature creates things," said Tangorra.

In future research, the team plans to look at other aspects of the sunfish's movement, including interactions between different fins and between fins and the fish's body. That will help engineers figure out how to best adapt nature's principles to designing robotic vehicles, Tangorra said.

"To be appropriate for AUVs, you can't just look at these as propeller replacements," he said.

This research is funded by the Office of Naval Research.


Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Massachusetts Institute of Technology. "Engineers Are Building Robotic Fin For Submarines." ScienceDaily. ScienceDaily, 31 July 2007. <www.sciencedaily.com/releases/2007/07/070730181502.htm>.
Massachusetts Institute of Technology. (2007, July 31). Engineers Are Building Robotic Fin For Submarines. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2007/07/070730181502.htm
Massachusetts Institute of Technology. "Engineers Are Building Robotic Fin For Submarines." ScienceDaily. www.sciencedaily.com/releases/2007/07/070730181502.htm (accessed October 24, 2014).

Share This



More Plants & Animals News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins