A robot fish developed at the U.K.'s University of Bath features a unique method of propulsion--a single fin rippling along its belly like a wave. Bath engineers say Gymnobot might inspire lighter, more efficient robotic submersibles.
Recent robot fish, such as MIT's, have flexible bodies, but Gymnobot is rigid save for a long undulating fin powered by twin crankshafts inside its body.
The design is a nod to freshwater knifefish, which can move forward and backward, and hover, by rippling an elongated ventral fin. The skin of the fin covers hundreds of fin rays that oscillate side-to-side, creating a wave in the water. Check out a black ghost knifefish moving here.
Other scientists have also examined this unique mechanism (PDF), though Bath engineers seem to be the first to build a model.
Gymnobot may be used to study biodiversity in oceans and rivers and help detect pollution. Its ventral fin would allow the robot to maneuver in shallower water than propeller-driven robots since propellers can get caught in reeds.
The lab is also building a robot manta ray to study fish stocks in the fjords of British Columbia.