AQUATIC AUTOMATONS: Mechanical engineers Kamal Youcef-Toumi and Pablo Valdivia y Alvarado have designed robotic fish to more easily maneuver into areas where traditional underwater autonomous vehicles can't go. Fleets of the new robots could be used to look for underwater oil; patrol ports, lakes and rivers; and help detect environmental pollutants. Image: © PATRICK GILLOOLY/MIT
Engineers have long looked to nature for clues that will help then build robots that move with anything close to the grace that living things exhibit. Although the use of rigid metal and plastic parts tends to result in stiff, mechanical motion, a team at the Massachusetts Institute of Technology (M.I.T.) is experimenting with the use of a single piece of flexible silicon and urethane polymer to create robotic fish that smoothly wriggle through the water much like their natural counterparts.
Fish propel themselves by contracting muscles on either side of their bodies, generating a wave that travels from head to tail. To mimic the motion, the M.I.T. researchers have created two different types of robo-fish.
The first type of aquatic automaton, which measures about 12.7 centimeters, mimics the carangiform swimming technique used by bass and trout. Most of the movement takes place in the tail end of the body, says Pablo Valdivia y Alvarado, a research affiliate working in M.I.T.'s Mechatronics Research Laboratory who has teamed with Kamal Youcef-Toumi, an M.I.T. mechanical engineering professor and the lab's director. Fish that use this type of motion are generally fast swimmers, he adds.
The second type is a 20-centimeter-long robo-fish designed to move more like a tuna or shark, which swim faster and for longer distances. The motion of these fishes (and dolphins, too) is concentrated in the tail and the region where the tail attaches to the body.