black ghost knifefish
February 17, 2014

Amazonian Fish Helping To Inspire Underwater Robot Development

redOrbit Staff & Wire Reports - Your Universe Online

The black ghost knifefish, a type of electric creature found in the Amazon basin of South America, has inspired researchers from Northwestern University in Evanston, Illinois to develop new aquatic technology that could be used to study coral reefs, repair damaged deep-sea oil rigs or investigate sunken ships.

According to BBC News Science Correspondent Jonathan Amos, black ghost knifefish let off a tiny current as they swim in order to sense their environment, and they move around by undulating a long fin. The authors of the new study believe they can take advantage of both features in order to create autonomous underwater vehicles capable of swimming through debris in total darkness.

Lead investigator Malcolm MacIver, an associate professor of biomedical and mechanical engineering at the university, presented his team’s findings Saturday during the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago. He also spoke on the topic of “Electric Fish Robotics” during a symposium on biologically-inspired engineering Sunday, February 16, at the Hyatt Regency Chicago.

“Our technology for working in water is not very advanced,” explained MacIver, who has studied the black ghost knifefish for two decades. “Current underwater vehicles are large and lack agility, which means that working close to living or manmade structures is nearly impossible. We've taken lessons learned from the knifefish about movement and non-visual sensing and developed new technologies that should improve underwater vehicles.”

“Just consider the sunken cruise ship. It is very dangerous to send divers into such situations where the water can be very cloudy,” he added in an interview with Amos. “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.”

In addition to possessing the ability to sense using electrosense (a weak electric field it generates around its entire body), the black ghost knifefish can swim in multiple directions using a ribbon-like fin on the underside of its body. MacIver and his associates in the Northwestern Neuroscience and Robotics Lab have currently developed over a half-dozen robots based on the knifefish, the university reported in a statement Saturday.

“From all our simulations, we now have mathematical relationships between things like the frequency and amplitude of the travelling wave and how much propulsion you get. So now we can put that into technology and get it to work properly,” MacIver told BBC News. His team is currently “demonstrating artificial sensory and locomotion capabilities on two separate robotic platforms” that they hope to bring together into one working device, Amos added.