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janrinok [soylentnews.org] writes:

The American Association for the Advancement of Science (AAAS) [aaas.org] is providing many interesting news items this week. This report involves building robotic fish inspired by the Black Ghost Knifefish [wikipedia.org] which senses its environment by producing and detecting minute electrical impulses.

The robotic fish would be able to swim in underwater situation where it would be impossible or too dangerous for a human to swim e.g. inside a sunken vessel or in heavily polluted water in limited visibilty

"Today, we don't really have underwater robots that work well in really cluttered conditions or in conditions where vision isn't useful," said Prof Malcolm MacIver [northwestern.edu], reported in a BBC news item [bbc.co.uk].

"Just consider the sunken cruise ship. It is very dangerous to send divers into such situations where the water can be very cloudy.

"But we can learn from the electric fish. They don't use vision to hunt at night in the rivers of the Amazon basin, and their movement through the cluttered root masses and flooded forests requires incredible precision. They fit a big hole in terms of our capabilities in underwater robots."

But it is the special propulsion technique employed by knifefish that the Northwestern researcher also wants to copy.

These are the ripples sent through the long fin on the belly. Undulate one way, and the fish will move forward; undulate the other way, and the direction of travel is reversed. Use counter-propagating waves that meet in the middle, and the fish will move up.

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