MUSEUMS and aquaria could soon be displaying lifelike robotic models of
marine creatures鈥攕ome of them long extinct鈥攖hanks to the efforts of
engineers at Mitsubishi Heavy Industries in Japan. The company has just
developed a remote-controlled sea bream that looks and swims just like the real
thing. And since you don鈥檛 need to feed the 60-centimetre-long fish or clean out
its tank, it makes an ideal exhibit.
The robotic sea bream is controlled via a desktop computer. This controls
movement of the tail fin and two pectoral fins. 鈥淚t wasn鈥檛 possible to replicate
the exact method of propulsion used by the sea bream,鈥� says Mitsubishi robotics
engineer Yuuji Terada. 鈥淪o we鈥檙e using an elastic oscillating fin that we first
developed for use in our underwater vehicles.鈥� The battery-powered fins
oscillate at between 0.2 and 1 hertz, and will propel the robot at up to 0.25
metres per second. The battery is automatically recharged by a coil inside the
fish that draws power from an electromagnetic field that permeates the fish
tank.
After spending four years getting the bream to swim accurately, Mitsubishi
says its next step will be to build a robotic replica of a coelacanth鈥攖he
鈥渇ossil fish鈥� that was once thought to be extinct. After that it plans to bring
back several extinct fish from the pre-Cambrian era.
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