Octopus-Inspired Robot Matches Real Octopus For Speed

KentuckyFC writes: Underwater vehicles have never matched the extraordinary agility of marine creatures. While many types of fish can travel at speeds of up to 10 body lengths per second, a nuclear sub can manage a less than half a body length per second. Now a team of researchers has copied a trick used by octopuses to build an underwater robot capable of matching the agility of marine creatures. This trick is the way an octopus expands the size of its head as it fills with water and then squirts it out to generate propulsion. The team copied this by building a robot with a flexible membrane that also expands as it fills with water.

The fluid then squirts out through a rear-facing nozzle as the membrane contracts. To the team's surprise, the robot reached speeds of 10 body lengths per second with a peak acceleration of 14 body lengths per second squared. That's unprecedented in an underwater vehicle of this kind. What's more, the peak force experienced by the robot was 30 per cent greater than the thrust generated by the jet. The team think they know why and say the new technique could be used to design bigger subs capable of even more impressive octopus-like feats.

Comments

Are these the smaller fish?

[Anonymous Coward]

The post says, "While many types of fish can travel at speeds of up to 10 body lengths per second, a nuclear sub can manage a less than half a body length per second."

How big are these fish? Body length does not seem like a good measure of speed, as it would tend to favor smaller fish over larger fish. There is no fish that is anywhere close to a sub in length (362' or 110 m is a reasonable size--ten times the longest fish). Even if you include whales (aquatic but not fish), the blue whale is less than a third the length of the typical submarine. A blue whale can't even go three body lengths per second, much less ten. Yet the submarine is still faster than a blue whale, although it can only go half a body length per second.