Octopus robot makes waves with ultra-fast propulsion

Octopus robot makes waves with ultra-fast propulsion
Octopus robot

Scientists have developed an octopus-like robot, which can zoom through water with ultra-fast propulsion and acceleration never before seen in man-made underwater vehicles.

Most fast aquatic animals are sleek and slender to help them move easily through the water but cephalopods, such as the octopus, are capable of high-speed escapes by filling their bodies with water and then quickly expelling it to dart away.

Inspired by this, scientists from the University of Southampton, Massachusetts Institute of Technology (MIT) and the Singapore-MIT Alliance for Research and Technology built a deformable octopus-like robot with a 3D printed skeleton with no moving parts and no , other than a thin elastic outer hull.

The 30cm long self-propelling robot is inflated with water and then rapidly deflates by shooting the water out through its base to power its outstanding propulsion and acceleration, despite starting from a non-streamlined shape. As the rocket contracts, it can achieve more than 2.6 times the thrust of a rigid rocket doing the same manoeuvre.

It works like blowing up a balloon and then releasing it to fly around the room. However, the 3D printed polycarbonate skeleton inside keeps the balloon tight and the final shape streamlined, while fins on the back keep it going straight.

The robot is capable of accelerating up to ten body lengths in less than a second. In recent laboratory tests, the robot accelerated a one kilogram payload up to 6mph in less than a second. This is comparable to a mini-cooper carrying an additional 350kg of weight (bringing the total weight of the car to 1,000kg) accelerating from a standstill to 60mph in one second - underwater.

This performance is unprecedented in man-made underwater vehicles.

Dr Gabriel Weymouth, Lecturer for the Southampton Marine and Maritime Institute at the University of Southampton and lead author of the study, says:

"Man-made are designed to be as streamlined as possible, but with the exception of torpedoes, which use massive amounts of propellant, none of these vehicles achieve speeds of even a single body length per second or accelerations of 0.1g, despite significant mechanical complexity.

"Rigid bodies always lose energy to the surrounding water, but the rapidly shrinking form of the robot actually uses the to help propel its ultra-fast escape, resulting in 53 per cent energy efficiency, which is better than the upper estimates for fast-starting fish."

The researchers calculate that making the bigger would improve its fast-starting performance, which could have applications in the development of artificial underwater vehicles that can match the speed, manoeuvrability and efficiency of their biological inspirations. The understanding this study provides could also have an impact in other engineering fields where drag is critical, such as airplane wing design, and to the study of different shape-changing biological systems.

Explore further

Robot looks like a fish to ride with marine life

More information: "Ultra-fast escape maneuver of an octopus-inspired robot." Dr Gabriel Weymouth (University of Southampton), Vignesh Subramaniam (Singapore-MIT Alliance for Research and Technology) and Professor Michael Triantafyllou (Massachusetts Institute of Technology), Bioinspiration and Biomimetics, The paper can be viewed here: iopscience.iop.org/1748-3190/10/1/016016/article.
Journal information: Bioinspiration and Biomimetics

Citation: Octopus robot makes waves with ultra-fast propulsion (2015, February 5) retrieved 22 October 2019 from https://phys.org/news/2015-02-octopus-robot-ultra-fast-propulsion.html
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Feb 05, 2015
Just when I thought it was safe to go back in the water.

Feb 05, 2015
For continuous propulsion, make it with multiple chambers instead of one big one, and inflate/deflate them in series, to create an undulating surface that moves from front to back.

For maneuverability, build it so it can bend in the middle, and alter the shape of the fins in the back. Maybe add spoiler-like structures.

Feb 05, 2015
Yay. More weapons.

Feb 05, 2015
I can see these as the next submarine mines, with plastic/polymer printed skeletons and very passive sensors, deployed as tiny little things that inflate when necessary they'd have a profile of nothing.

Then with simple target acquisition, lock, procedures you could effectively deliver a potentially devastating payload to a target with very little chance of interception.

I don't see much by way of commercial potential in this design though, i think super cavitation, some form of super hydrophobic material will be necessary to create the kind of slippage necessary for bulk freight/movement of large mass through seas/oceans.

Feb 05, 2015
Serious science? And this endeavor took collaboration of 2 MIT institutions?

Water rocket and balloon propulsion toys have been around for many many years. Sorry to say, I don't see one and a half seconds worth of significance here at all.

Feb 05, 2015
what a piece of shit ! wow it has a long range.. hahaha

Feb 05, 2015
Uh, I was about 7 years old back in the early 70s, and used a water weenie to goose the girls under water. Much faster than the MIT thing and fun!

Feb 06, 2015
Uh.... I don't think inflating a balloon with air is science. This comes from MIT? Wow MIT way too go. You reinvented what every child who had a bath or swimming pool already Knows.

Feb 06, 2015
Well it seems fairly intuitive to me. One of those ah ha moments. I suppose this will ultimately lead to a new generation of pool toys or something?

Feb 08, 2015
How big would an Octobot have to be to tow one of these? http://www.worlds...-ship-2/

Could you use a team, like a dogsled? Or the many chambers like dnatwork suggests?

How do you refill the chamber for another squirt? It might not take much energy if the "muscles" of the balloon could be relaxed. Maybe solar would be enough.

I can foresee "growing" biosynthetic versions in the ocean.

How about a fleet that goes counter to the Pacific gyre to collect all the trash at various depths?

Feb 08, 2015
I need to see repeated cycles before I'll be impressed. Needs to have one way valves at the front and back. So when it re-inflates, it sucks itself forward by sucking more water in, then expels water out the back when deflating. The re-inflating bit is going to put a serious dent in it's velocity though, so I'm unsure how well it's AVERAGE velocity will be instead of this half cycle video we just saw.

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