Cuttlefish-Like Robots Are Far More Efficient Than Propeller-Powered Machines (interestingengineering.com) 49
New York-based firm Pliant Energy Systems is building a marine system reminiscent of the cuttlefish with its rippling underwater motion, a report from The Economist reveals. The company's biomimetic machine, called Velox, is based on the principle that propellers are nowhere near as efficient as the fins of sea creatures that are prevalent in nature. Interesting Engineering reports: Unlike propellers, fins and flippers can extend around a sea creature, meaning more propulsion without the need for a large protruding propeller that could get caught or damaged by hitting the seabed. Fins are also flexible, meaning that if they do come in contact with any other object in the sea, they are less likely to get damaged. In an interview with The Economist, an ex-marine biologist and founder of Pliant Energy Systems, Benjamin Pietro Filardo, explained how he is designing submersible machines that are propelled using flexible fin-like materials. He said Velox will produce approximately three times as much thrust per unit energy as the average propeller of a small boat. The system can travel underwater and even come out onto land, using its fins almost like robotic legs. The video below shows Velox skating on ice and swimming in a pool.
Filardo showed his new design to America's Office of Naval Research, leading them to commission a new iteration, called C-Ray, that will be faster and lighter than Velox. C-Ray also won't be tethered, unlike Velox, which is currently controlled via a cable. Autonomous swarms of the machine could eventually be used for missions such as undersea patrols, mine removal, and deepsea exploration and monitoring. [...] Filardo said the system has great potential for scalability, giving the blue whale as an example of a massive sea mammal that uses fins for propulsion. Impressively, he also revealed that he is also working on a concept that would allow his system to moor itself, and then use the undulations of its fins, thanks to the sea current, to recharge. A lot of testing is still needed, but if Filardo's system delivers on its promise, we might eventually see giant mechanical sea beasts silently gliding through the oceans.
Filardo showed his new design to America's Office of Naval Research, leading them to commission a new iteration, called C-Ray, that will be faster and lighter than Velox. C-Ray also won't be tethered, unlike Velox, which is currently controlled via a cable. Autonomous swarms of the machine could eventually be used for missions such as undersea patrols, mine removal, and deepsea exploration and monitoring. [...] Filardo said the system has great potential for scalability, giving the blue whale as an example of a massive sea mammal that uses fins for propulsion. Impressively, he also revealed that he is also working on a concept that would allow his system to moor itself, and then use the undulations of its fins, thanks to the sea current, to recharge. A lot of testing is still needed, but if Filardo's system delivers on its promise, we might eventually see giant mechanical sea beasts silently gliding through the oceans.
Nice (Score:3)
Looking at the concept, I can't see why it wouldn't be usable on much, much larger ships as well.
Re:Nice (Score:4, Funny)
Possibly... But docking into port is going to be... well.. different?
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Yes, and going through the Panama canal might be tough. Those ships don't have a lot of room. [wikimedia.org]
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Well, since they are under tow, the fins can be folded upwards, watch for low bridges though
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I was thinking that, but then how would it move?
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:-) I think I said they are under tow, by a rail locomotive of all things
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Many ports have limited depth as well. Large ships sometimes transfer their cargo without docking.
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So maybe the class of ship using the cuttlefish propelling method has slightly smaller bodies, but makes up for that limitation by being much more economic on fuel.
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Re: Nice (Score:2)
Could you elaborate? What kind of maintenance do you think is difficult to perform, and how so?
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I can image the (rubber?) mats to loose their properties over time and need faster replacement than propellers? And if made out of a lot of wristwatch-like metal links then that means lots of moving components, bearings, etc. So oils, wear and tear, etc.
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Re: Nice (Score:5, Interesting)
I think the mats would be less of a problem.
To answer parts of your question, plenty of other materials come to mind (teflon?), although I don't know all their properties. In any case I'd imagine they're more easily and cheaply manufactured than propellers.
But as another slashdot user (fazig) was pointing out, maybe the moving parts, i.e. the arms moving the mats, amount to more maintenance, there being more of them.
OTOH I'm not sure how the whole concept scales. With big, heavy rubber arms, coordinated movements may be not viable for large shipping. So there may need to be done some more development, or the way we do shipping might have to change (many small vessels instead of large ships).
I think the point of the current demo may have been only to show that there is energy efficiency to be had, not necessarily to be a demo of the complete tech stack.
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The propellers are wonderfully efficient: ...)
-the ship engine acts on the propeller, either directly or via a very simple reduction gear
-the propeller shafts go below the actual cargo hold
-the entire engine room is relatively compact, and everything outside it can be used for cargo (or fuel, or living quarters, or
-outside of cleaning, there isn't much maintenance needed on the ship propeller
-the propeller is relatively compact (compared to the size of large ships) and doesn't protrude much
Meanwhile, a "fin
Re: Nice (Score:4, Insightful)
"Wonderfully! efficient" with regards to what? Mechanics and space considerations, by your account - because the article says that the fins have a 3x efficiency of movement with regard to energy input.
Propellers move fast (orders of magnitude fasyer than the ship), being subject to a lot of drag. They create vortices, those cost energy. Sonoluminescence and other cavity effects. You say they are very loud, even across large distances: where do you think the energy for the noise comes from?
You're also evaluating current ship and motion design, optimized for propeller propulsion, for its fitness for fin propulsion. If you do that, you're cheating yourself in your assessment. It is like stating "combustion engines are more efficient in cars, because if you swap the engine for an electrical one, all the rest remaining the same, your trunk will be full of batteries and unavailable for luggage". This ignores the fact that electrical propulsion for cars works fundamentally different from combustion.
In shipping, rotational (fairly) high speed motion is what we optimized for because that's what we had and thought we needed, until now. But there are better, more modern designs possible: compact, linear electrical engines that just swipe up/down and require no gear, and almost moving part apart from the sled attached directly to the fin, artificial muscles (yes, we have those, too) that could mimic the way fish actually generates motion etc.
How this translates to efficiency per-payload is difficult to say as long as we haven't had time to make a serious effort to actually optimize vessels for this type of propulsion.
Again, the key takeaway here is higher motion vs energy efficiency that comes from fewer losses in contact with the medium itself (water). Everything else is just speculation.
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Modern single prop systems are still 0.75-0.8 efficient in their peak range (where the ship will be designed to run for 99% of every trip).
That means you're looking at getting about 16% more propulsion from a system like the one in the article (3x the efficiency is only working on that 25% existing loss). For a pretty extreme increase in mechanical and control complexity (including the number of joints needing protection from salt water), plus cutting into cargo space and puncturing the hull in multiple pla
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Modern single prop systems are still 0.75-0.8 efficient in their peak range (where the ship will be designed to run for 99% of every trip).
Without specifying what you actually mean by that (i.e. efficiency of what vs what), this value is useless.
For example: if you calculate the energy input (i.e. fuel) vs the motion output (i.e. momentum change of the vessel), this is waaay off, probably by one order of magnitude or so.
The Carnot-cycle [wikipedia.org] has a maximum efficiency that is below that. Ant the Carnot-cycle is a theoretical maximum, typical real-world internal combustion engines have an efficiency [wikipedia.org] much below that.
Now I know jack shit about ship engi
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Until we get there, which will be another 9 years at least, moving parts in a system that can't regenerate itself translates into wear and failure which is combated by maintenance.
The rule of thumb in engineering there is: more moving parts -> more bad.
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You have an interesting point but there is a principle of scale that usually applies. Please note that I am not saying you're wrong. Elephants and mammoth are the largest mammals I know of to have lived on this planet. It has something to do with the square root or something. I don't see why those basic principle couldn't apply to marine life as well or why it could apply at larger scale.
Re:Nice (Score:5, Interesting)
Otherwise there's a limit to body size based on the metabolic heat that a living organism generates. A large organism needs a sufficient enough cooling mechanism to transport heat from inside of the body to the outside before temperatures get high enough to cause cellular damage. This is also an issue of stranded whales, because compared to water, air is an insulator. So once the water on their skin has done it's coolant job by evaporating, whales start to overheat on top of their organs being crushed.
A machine with a well designed cooling system as well as well designed structural integrity can go beyond those limitations, while of course the larger they grow in size cooling and integrity becomes more challenging to tackle.
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I know, I like to keep a low profile but thanks for that
Re: Nice (Score:2)
Cooling is a lot easier when you are submerged for the most part, why do whales have so much blubber if heat is an issue for huge mass animals
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When those mammals are submerged in water, those blood vessels can contract and dilate depending on external and internal circumstances affecting the thermal conductivity through the blubber, forming a main component in regulation of body temperature.
Re: Nice (Score:2)
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Not sure that efficiency is a big problem with propellers or ships.
Given the amount of fuel used by them, a 10% boost if it came with no other issues, would be very much welcomed, I suspect.
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Not sure that efficiency is a big problem with propellers or ships.
It's a MASSIVE problem.
Re: Nice (Score:2)
Doesn’t make sense. (Score:5, Interesting)
Boat propellers are already 75 to 85% efficient, so there’s no way this thing could be 3 times more efficient.
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Yeah, it's worded in a very sneaky way. I imagine he is referring to the static thrust production for a given power input. As the system has such a large fin area vs vessel size, I imagine it can produce static thrust much more efficiently than a typical boat with a propellor optimised for operation at medium/high speed.
But you can basically produce any level of static thrust 'efficiency' you want if you just scale [wikipedia.org] up a propellor's size so it is a completely meaningless thing to compare. It's basically like
Re:Doesn’t make sense. (Score:4, Informative)
Well a nice clear cite seems a little elusive but I did find a graph:
https://www.boatdesign.net/dat... [boatdesign.net]
But I don't really think the efficiencies you imagine are actually comparable - apples & oranges you know.
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When they say 3x as efficient, they mean losses are 1/3 that of a prop. So 75% efficient becomes 91.5%.
It's a sneaky way of making a smaller increase look big, when you're actually getting about 16% more mileage for your bunker (in theory).
ok. (Score:3)
Silent submarines? (Score:5, Interesting)
AI/ML/VR "aliens" (Score:2)
Barely registering on sonar as harmless "biologicals", the robot cuttlefish approached the nuclear submarine. They successfully attached themselves to the vessel and rode for nearly 70 minutes.
Unfortunately, at that point they were lost, and subsequent attempts to communicate using the LRCS (long range communications sonar) failed.
Each cuttlefish was equipped with a NeoLogic NLL303 Learning chip. The cuttlefish navigation system is based on an internal "virtual world" that models the real world mission envi
Quieter? (Score:3)
I suspect these would have lower peak noise levels than propellers, which would make them much friendlier to marine life. Also, propellers suffer from cavitation, which can damage them - but by the looks of these things, cavitation won't be an issue.
Re: Quieter? (Score:2)
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Actually, it appears that tuna and salmon can reach speeds where cavitation might be an issue on their fins and tails. Tuna "folds in" some of their flippers, I think
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Cool - thanks for that info!
Name borrowed from history (Score:2)
http://worldwideinvention.com/... [worldwideinvention.com]
Does it scale? (Score:2)
This looks great for amphibious robots, emphasis on "amphibious". But does it scale to the size of a landing craft?
Re Inventing the fin (Score:2)
I remember a device from the late 1950's or early 1960's that was designed to be clamped to the stern of a fishing boat at a private lake where my dad was a member.
He had one of these things that had a tiller like handle extending above the transom of the boat and underwater there was a fin that was hinged to the shaft. By moving the tiller back and forth you could both propel the boat and control its direction.
I have no idea what these were called, but they were very easy to use since as a pre-teen my da
extremely misleading, it's not energy efficiency (Score:2)
This is the problem with "science" reporters, they really don't have any grounding in the subjects they're reporting on.
The greater efficiency they're talking about, of which I'm sure there is some, is probably something entirely different than what most people think of when they hear the
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First thing I thought.when I read the article.
Thrust / power is the wrong units (Score:2)
Power = force * velocity. So a tug of war is not a fair contest - you can always make a device the moves a larger volume of water more slowly and provides more thrust per power.
The fair comparison is comparing thrust at some agreed-upon speed through the water. Propellers are already pretty good efficiency (~80% or higher) so there is not
I bet they aren't much more efficient than... (Score:2)
...a well designed propeller, at 80%. At best they can be 25% more efficient, and of course, they won't be.
In the 1920s they were designing propellers that had an efficiency (measured obviously) at top speed of 60-70%