Ankle Exoskeleton Takes a Load Off Calf Muscles To Boost Walking Efficiency

Zothecula writes We might have started off in the water, but humans have evolved to be extremely efficient walkers, with a walk in the park being, well, a walk in the park. Human locomotion is so efficient that many wondered whether it was possible to reduce the energy cost of walking without the use of an external energy source. Now researchers at Carnegie Mellon and North Carolina State have provided an answer in the affirmative with the development of an unpowered ankle exoskeleton."

Comments

You've got braces on your legs...

[BitwizeGHC]

... so you're all set. Although, no braces on your arms, though, so you're going to have to rely on the old human strength to keep a grip on the device and, by extension, me. So do make sure to keep a grip on me.

Also a note: no braces on your spine, either, so don't land on that. Or your head, no braces there. That could--that could split like a melon from this height. [nervous laugh] So do definitely focus on landing with your legs.

Re:You've got braces on your legs...

[Anonymous Coward]

... seriously? Google that next time before you spout off in a rage.
(
hint: it's from Portal
http://theportalwiki.com/wiki/Long_Fall_Boots
)

Water?

[spauldo]

Humans started out in the water?

I mean, life started out in the water, sure, but there was a lot between the first creatures to leave the sea and humans.

Unless you're referencing that theory that humans evolved near the ocean, hence our relative hairlessness and whatnot. I thought that theory was out of favor.

Re:Water?

[Anonymous Coward]

Indeed, I thought modern humans evolved in Olduvai Gorge.

Re:Water?

[pthisis]

Indeed, I thought modern humans evolved in Olduvai Gorge

The Omo River site in Ethiopia is the current frontrunner, I believe.

https://en.wikipedia.org/wiki/...

Re:Water?

[Livius]

Humans are life.

Re:Water?

[spauldo]

So are snakes, which aren't particularly known for their walking abilities.

Re:Water?

[Truth_Quark]

I thought that theory was out of favor.

Less "out of favour" and more "never had any scientific attention or merit", also "lacking any archeological or fossil evidence".
See Space Ape!

Re:"Unpowered"

[Urkki]

The energy to load the spring comes from the user as part of the normal operation cycle. That makes it unpowered.It does not bring extra energy to the operation (user walking by converting chemical energy to muscle contraction), it only changes how the energy is used.

The trick is to define the system and timeframe you are looking at sensibly. In this case you have the braces and the user taking a number of steps. The user generates the power, the braces are unpowered. If you looked at the braces for one unloading of the spring, you could say the frame is powered by the spring, but that is not very useful choice in most contexts outside design of the device.

Great!

[jargonburn]

With a pair of these, I'll be able to get my fat ass up and grab some more Cheetos without getting out of breath!

Re:"Unpowered" Energy ;)

[Paradise Pete]

Heh. This must be some new kind of energy ...

It's not adding energy, it's avoiding some of the loss. A chair does a similar thing. By using that you expend less energy than by having to maintain your balance by standing.

Allowable or forbidden in competitive sports?

[evilsofa]

The Olympic Committee, professional sports of all kinds, scholastic sports, athletics, and so on. Will these be allowed? Will they be disallowed? Is there already rules in the books that cover something like this, or will there have to be a flood of new rules in every sports organization to cover unpowered exoskeletons of all kinds?

Re:Allowable or forbidden in competitive sports?

[Njorthbiatr]

Unless your sport is casual walking it won't.

Re:Allowable or forbidden in competitive sports?

[Antique Geekmeister]

This has basically already happened.

                        http://en.wikipedia.org/wiki/O...

Oscar was a double amputee, and a research subject for some fascinating "blade" prosthetic legs who won olympic gold medals for running. Some of the creators of the devices made the same kind of elementary mechanical mistake as some of the posters here: There is a fascinating documentary on Oscar's case, where one of the leg designers said "If they're unpowered, how could they possibly provide an advantage?"

Some careful scientific review, well documented at the Wikipedia article, showed that the legs gave profound mechanical advantages over normal, organic legs for running in a straight line, and contributed significantly to Oscar's win. Fascinatingly, another review tried to weigh the pure efficiency advantages for straight running against the disadvantages for turning and starting, and concluded that overall Oscar gained no advantage.

It was a fascinating case, and helped the Olympic committees set some reasonable guidelines for mechanical assistance in athletic events.

Re:Allowable or forbidden in competitive sports?

[BarbaraHudson]

Remember those incredibly flexible poles used for pole-vaulting? The ones that bent like crazy, then straightened to boost the pole-vaulter to unheard-of heights.

Re:First Step toward MANTIS

[jellomizer]

It might help with people who have injured calf muscles where that extra 10lbs can help out a bit.
But effenancy isn't good for exercise as we want to burn calories and build up muscles.
However it could be used for jobs where there is a lot of walking where the effenancy can allow you to have enough energy at the end of your shift to be more effective.

Still some way to go

[ScaredAmoeba]

This invention still does not counter the rise and fall of the upper body that occurs with each step, therefore this cannot address that lost and wasted energy. That's what makes cycling so efficient compared with walking, and presumably compared with this invention..

Re:Still some way to go

[tburkhol]

This invention still does not counter the rise and fall of the upper body that occurs with each step, therefore this cannot address that lost and wasted energy.

The motion of the center of mass is not where the metabolic power of walking goes, any more than the rise and fall of the mass of a pendulum requires external power. That's kind of the point of this: the potential energy of the high center of mass converts to kinetic energy at the low center of mass like a pendulum, and elastic mechanisms in your tendons let you 'bounce' off the ground. This device reduces the muscular effort required to bounce.

Most of the energy cost lies in lifting each leg and swinging it forward with each step. You don't have to do that on a bicycle, and its why the widget is only good for ~7% of total energy cost.

Re:Still some way to go

[dfghjk]

I'm impressed by the stupidity displayed in this comment.

If what you say is actually "the point of this", then you've proven your very first claim false. If the device is designed to recover lost energy in the motion of the center of mass, then there must be lost energy there unlike the motion of a pendulum. It's not a "bounce" if it requires "muscular energy" for its movement.

On a bicycle you absolutely have to move your leg up and forward with each pedal stroke. It cannot get there any other way. Now, the leg may be moved there by the effort of the other leg or it may not, but either way the energy comes from you and nowhere else.

You should probably just stop talking.

Re:Still some way to go

[bluefoxlucid]

It's funny, too: humans are so efficient walking that we don't know if we can make them walk any more efficiently, but we do know that they use as much energy to walk 1 mile as they use to bicycle 7 miles.

Re:Still some way to go

[bluefoxlucid]

A pendulum is powered by the rotational energy of the earth in its orbit around the sun. It has the largest external power source in the world.

Re:Still some way to go

[rjstanford]

On a bicycle you absolutely have to move your leg up and forward with each pedal stroke. It cannot get there any other way. Now, the leg may be moved there by the effort of the other leg or it may not, but either way the energy comes from you and nowhere else.

Ooh, here's an idea to improve bicycles forever! Your gluten are really good at pushing down but you're right, pulling up and over is a weakness for many people. What if - I know its crazy but stay with me here - what if we connected the two pedals so that instead of being independent, a tiny amount of the force that you push down with your big muscle groups could be used to help the other leg get into position for the next stroke?

I'mma gonna patent this right now. It'll make million$!

Re:Still some way to go

[moeinvt]

Uhhhh, I think the presence of the cycle is what makes cycling more efficient than walking.

Re:Still some way to go

[Immerman]

Say what? No.

A pendulum is powered by the person who raised it for the first swing - after that its energy is cyclically transformed from gravitational potential energy to kinetic energy and back again. Perhaps you're thinking of the giant pendulums whose swinging plane slowly rotates - that rotation is indeed powered by the motion of the Earth (or more accurately, demonstrates the rotation of the Earth under the pendulum), but the energy of the swinging itself is all imparted when the pendulum is first raised, and gradually diminishes as losses to air resistance, etc. gradually accumulate.

Re:Still some way to go

[Immerman]

Actually, it probably does. It sounds like a mechanical version of what kangaroos accomplished by evolving an elastic Achilles tendon - when "running" they move vertically quite a bit, but unlike muscle which can't store energy, their tendons can stretch on landing and then return virtually all of the absorbed energy on the next jump, making them the most efficient runners on the planet, almost up to what can be accomplished with wheels.

Re:Still some way to go

[HornWumpus]

Even worse: 'orbit around the sun'.

I think the GP qualifies as 'not even wrong'.

Re:Still some way to go

[mark-t]

Cycling isn't walking. It might be unpowered (save for human muscles), but its definitely not walking... if you are going to argue that moving around in this unpowered exoskeleton isn't really walking either, then you might have a point.

Re:Still some way to go

[bluefoxlucid]

Pendulums swing forever. Have you not seen a pendulum? They get momentum from the rotation of the earth. There's a pendulum that has been swinging since 1855; that doesn't just happen by magic.

Re:Still some way to go

[bluefoxlucid]

Cycling is unpowered. Walking is unpowered. Both use the same human muscle system and human fuel system, but one accomplishes locomotion with 1/7 as much energy. Walking is obviously very inefficient, and to claim humans are so efficient at walking that we don't know if we can make them any more efficient is ludicrous; there is obviously a lot of loss in the system to look for.

Re:Still some way to go

[mark-t]

Of course there are more efficient systems for getting around.... but is there much room for improvement for the practice of walking itself?

Walking may admittedly be overall quite inefficient as a means of motion when you compare it to something like cycling, but how humans walk still might be as about efficient as the practice of walking itself can still physically get.

Re:Still some way to go

[bluefoxlucid]

but is there much room for improvement for the practice of walking itself?

Of course there is. If it's less efficient than cycling, then energy is lost somewhere in the system. Walking carries a stop effect that brings a mass to rest by dissipating the motion energy from heat; it carries friction and deformation effects from elastic pressure on joints and tendons; it carries loss in the form of inelastic muscle movements, pulling one way and then the other; it even carries a loss from fighting against gravity to lift the leg, and then not storing the gravitational potential when dropping the leg (e.g. in a spring system or elastic tendon). All of these offer potential efficiency improvements.

Re:Still some way to go

[Immerman]

Only in a frictionless vacuum so that there's no energy loss. Or if there's an external energy source powering it (such as the hanging weights on an old-fashioned pendulum clock.) I have seen many pendulums, and they all slow down over time.

There are indeed some Foucault pendulums that have been on display for decades maybe even centuries, but they require someone to come along and boost their swing periodically - they don't magically suck power out of the motion of the Earth, they just demonstrate its rotation as the Earth rotates under the plane it's swinging in. Maybe, just maybe, if you designed the frequency and position *just* right you could construct a pendulum that would do such a thing, but it's hardly a general property.

Re:Still some way to go

[bluefoxlucid]

The original discussion was on the claim that a pendulum swings forever without input energy, which is only true for certain pendulums, and so these are the pendulums being discussed.

The pendulum is carried by the rotation of the Earth; it's not in a fixed location, swinging in the same spot while the Earth moves under it. It changes its trajectory because the Earth passes some of its momentum to the pendulum.

Am I going to have to get Randall Monroe on this?

Re:Still some way to go

[Immerman]

No, the original discussion was relating the rise and fall of a person's center of mass to that of a pendulum, where no external energy is (necessarily) needed - nothing was said about pendulums swinging forever until you made your ridiculous claim.

There may be some small amount of momentum transfer between pendulum and planet (rotation only though, nothing that would impact its orbit around the sun), which is why I said it *might* be possible to construct a "perpetual" pendulum if you specifically attempted it - but so far as I've heard nobody has ever even attempted such a thing. What would be the point? At least a Foucault pendulum offers a concrete demonstration of the Earth's rotation, a perpetual pendulum would be nothing but a large, expensive novelty.

Moreover, any such pendulum would be dynamically unstable so wouldn't actually be perpetual anyway - either it's not extracting quite enough momentum, in which case it will wind down, or it's extracting too much, in which case it will eventually rip itself apart. Thanks to the physics involved a pendulum's period depends only on it's length, and each swing will take exactly the same amount of time whether it's barely moving or swinging wildly, so there's no possibility of a negative feedback loop offering dynamic stability. Even if you tuned it perfectly, the first change of air pressure would destabilize it.

And actually - any momentum transfer could only be transmitted through the pivot point - which means that any momentum transfered in the current swinging plane will be neutralized during the opposite half of the swing. So the only possibility for net momentum transfer is perpendicularly to the swing plane, which would alter the direction of the swing far more than the magnitude.

Re:Still some way to go

[bluefoxlucid]

The motion of the center of mass is not where the metabolic power of walking goes, any more than the rise and fall of the mass of a pendulum requires external power.

Re:Still some way to go

[mark-t]

Of course there is. If it's less efficient than cycling, then energy is lost somewhere in the system

Its less efficient than cycling, as was pointed out above, but again.... cycling isn't walking. I'm not arguing that there are much more energy efficient means of unpowered locomotion, the article merely suggests that the way that humans have evolved to walk may very well be nearly as efficient as *walking* can physically get.

The fact that there provably exists far more efficient modes of externally unpowered movement that no longer qualify as walking in the first place is entirely beside the point.

Suggesting that walking could be made more efficient simply because cycling happens to more efficient than walking is a complete non-sequitur, at best. It's like suggesting that you should be able to get just as much energy out of a coal furnace as a nuclear one of the same size. You have to completely change the way you are using the energy in the first place to get that much more efficient energy utilization, and after you've done that, you will end up with something that is no longer in the same category of system where you started (coal furnace vs nuclear furnace). Using this exoskeleton to move around is marginally more efficient than walking without it, but I'd suggest that using it still at least qualifies as walking. If you are going to argue that it doesn't, then that's a different matter... but it doesn't defeat the point being made about the way humans walk being very efficient

One might conclude that the only way to make unpowered locomotion much more efficient than how humans walk is to resort to mechanisms that no longer qualify as walking... cycling being just one obvious example.

Re:Still some way to go

[Immerman]

Yes - nothing there about perpetual motion, simply a reference to pendulum motion - you don't have to add energy on every swing, it will continue to to rise and fall without any external power source (at least until entropy robs it of it's momentum - but if we have to state that explicitly in *every* conversation it's going to get really tedious. Should we add "under the influence of gravity" as well?)

Re:Still some way to go

[bluefoxlucid]

It's like suggesting that you should be able to get just as much energy out of a coal furnace as a nuclear one of the same size.

There's more actual energy in a nuclear pile than in a lump of coal. You should, in theory, be able to get just as much energy out of an 1100 degree coal furnace deriving 500kW of chemical energy from the coal as you can out of an 1100 degree nuclear reactor deriving 500kW of nuclear energy from the fuel.

Again: we know we use as much energy to bicycle some distance as we use to walk some shorter distance in a longer time. That tells us walking is inefficient, and thus that the mechanism of walking has systemic losses, and thus that there are systemic losses to target. Bicycling and walking are not greatly different: bicycling suspends a mass on a frame supported by a rotating surface, laying ground contact surface in front of ground contact surface by rotation; walking suspends a mass on a frame supported by a moving part, but still relies on moving that frame forward by placing material more forward, albeit in a reciprocating instead of a rotating manner. You're, thus, looking at reciprocation losses, losses in friction, and so forth, which means mechanisms such as flywheels and springs should make your energy consumption substantially similar to that of bicycling.

The power stack is the same in both. We're not arguing about the efficiency of the power stack; we're arguing about the efficiency of transferring the power. The only differences are the rigid frame suspension and the movement of the frame itself; a bicycle and your legs are both acting as the vertical support. The theoretical difference is, thus, the difference in loss between converting between gravity (i.e. bouncing on a spring versus sitting atop a rigid steel frame) and in the mechanical differences (levers and hinges versus axles and bearings).

You'll notice a bicycle suffers spring loss in suspensions, while humans suffer complete loss when they allow their legs to flex and lower their weight--they need to expend energy to lift, rather than use an elastic ligament (a spring) to store that potential energy. You'll notice wheels rotate with forward momentum, while a human's gait may cause braking--we know Nike's original theory of running faster by cushioning heel strike was a mistake, and now runners try to land on the balls of their feet to prevent the braking effect. You'll notice many things which are similar, but suffer various improvable forms of mechanical loss. You'll also, undoubtedly, notice the only real difference is what holds up the human's weight and what provides the ground surface contact for propulsion.

We're not comparing a diesel versus an otto engine; the engine is the same. We're comparing wheels versus reciprocating pods at the ground contact point.

Re:Still some way to go

[bluefoxlucid]

You're telling me that the statement was that a center of mass continues to move forever when walking and requires no energy to keep it moving? That a person with more weight strapped to him--50 pounds strapped to his chest--won't have to work any harder to walk down the street than a person who has nothing attached? That's what the statement indicated?

... it did apparently indicate that yes; just like it indicated that a pendulum, once set in motion, continues to rise and fall with no external power. No energy is required to keep a pendulum moving.

Energy must come from somewhere to keep a pendulum moving. Pendulums that move forever are gaining their momentum from the rotation of the earth.

Re:Still some way to go

[mark-t]

Again, it's not being suggested that walking is necessarily the overall most efficient means of unpowered transport, or necessarily anywhere even close... rather, it is being suggested that the way humans do it is about efficient in energy usage as you can physically get and still be able to actually still *call* it walking, and not just simply generalize it as "unpowered locomotion".

Cycling may use the same muscles as what walking does, but cycling isn't walking. You use the same muscles as walking while roller blading, arguably even more similarly to walking than cycling is, but that's not considered walking either.

The question at hand, however, is can *WALKING* be made much more efficient than the way humans do it naturally? This exoskeleton only improved efficiency very nominally... And the fact that there can exist no shortage of ways to get from point A to point B using the exact same muscles as walking far more efficiently than walking, but without walking in the first place, is entirely irrelevant.

Re:Still some way to go

[Immerman]

No, that was *their* claim - inaccurate in my opinion because humans *don't* have particularly elastic tendons. Kangaroos though *do*, and are by far the most efficient running animals on the planet. Despite their dramatic vertical motion they're nearly as efficient as wheeled vehicles.

Right, no external energy is required to keep a pendulum moving, for a while - entropy will eventually win, obviously, but you don't have to introduce any new energy to get the pendulum to climb back up the opposite side of it's swing. It won't climb quite as high as it started, but the initial energy is mostly conserved.

You are the only one suggesting that pendulums swing forever - they don't. Never have, and never will (barring the creation of a perfect vacuum and a 100% frictionless pivot). You can fake it by adding a mechanism to introduce additional energy to counteract friction losses, but then you're no longer talking about a simple pendulum, you've created a much more sophisticated machine.

Re:Still some way to go

[bluefoxlucid]

In theory, you can set up a set of mechanical levers and springs so that the human legs place the feet flatly on the ground one after the other in the same way that a wheel places rubber on the ground in front of rubber, albeit in wide steps instead of a continuous roll; but the legs would be attached to a rotational system, such that the energy delivery is done like a wheel.

Think like a bicycle with shoes tied to the wheels. Then think like a system that abstracts that away, using the wheels to power a system of springs and levers that just places shoes on the ground as the wheels turn. Then think of a system that converts reciprocating energy into rotational energy to power that--walking is reciprocating--and then attach that to the legs, and bam: you've got something substantially close to a bicycle, except you're going trot trot trot.

Springs can be replaced by elastic ligaments, which the human body uses.

Re:Still some way to go

[bluefoxlucid]

No energy is required to keep ME moving--for a while. I have momentum when I take ONE STEP.

You're making a distinction between "it rolls for a while once you push it" and "it only rolls like, half an inch." In both of these situations, the thing stops; it requires additional energy to keep moving. To state that a pendulum doesn't need additional energy to keep moving is to state that a pendulum will carry its full swing FOREVER, not FOR A LITTLE WHILE or FOR A THOUSAND YEARS BEFORE FINALLY WEARING DOWN. If it ceases to move, ever, by any mechanism other than mechanical breakdown, then it needs additional energy to keep moving; that doesn't change just because it keeps moving for a long time instead of for just a fraction of a second.

Re:Still some way to go

[Immerman]

You're being pedantic. NOTHING ANYWERE moves forever, not even orbital systems, though they slow down much slower thanks to the near-vacuum they operate in.

The point is, there is no *inherent* reason in an *idealized* system why the cyclic motion in walking (or pendulums) needs to consume energy. So long as energy is being lost, there's the potential to reduce those losses to get arbitrarily close to zero. Contrast that to lifting a box, wherein the input energy has an absolute minimum equivalent to the change in potential energy, and the losses are in addition to that.

Re:"Unpowered" Energy ;)

[Anubis IV]

Don't be obtuse. It's clear that what they're getting at is that it isn't externally powered when they say it's "unpowered".

Moreover, you've failed to consider how different efficiencies can affect the situation (i.e. the real world is not a frictionless vacuum). Yes, moving more mass means requiring more energy...output energy. But what we're concerned with here are inputs, since that's what we're expending.

Just to drive home the importance of the distinction between inputs and outputs (and also to toss in an obligatory car analogy), consider the Tesla Model S. It weighs about 50% more than a Toyota Camry, which means it'll take a greater energy output to move than the Camry. That said, the Camry's engine is only about 1/3 the efficiency of the Tesla's, which means that despite its lighter weight you'll still have to put more energy into it than the Tesla to get it to move the same distance.

The same applies here. Yes, adding an extra mechanism adds more weight, which means that the necessary energy output is greater. That said, your calf is inefficient at locking up during the downward part of your step, whereas a mechanical clutch is quite efficient at locking up, so by relying on simple machines to divert those forces to the clutch instead of your calf, you can reduce your dependency on an inefficient system (i.e. your calf), thus reducing the amount of input energy necessary, to the tune of 7%.

Or, hey, it's impossible. Because efficiency isn't a thing. How do you breathe in a frictionless vacuum, anyway? :P

Re:"Unpowered"

[Hognoxious]

Think of a self-winding watch. It doesn't really wind itself, you (or your cat) wind it by moving around while wearing it.

More details

[fgouget]

It would be nice to have more details. Does this device need lots of tuning for each user? It seems like it would a bit if only to adapt to size. Does it help if one is running too? Would it help marathonians get better times? What about sprinters?

Re:More details

[slashdot_commentator]

Frankly, I see this having more use for people "needing" to hike for long distances (10-20mi) under weight.

Re:More details

[plover]

According to the article in Nature at http://www.nature.com/news/exo... , it only improves normal walking speed on level ground.

Which is too bad. My sister in law's right side was mostly paralyzed by a stroke. She shuffles around, swinging her body weight on her good leg, and is quite the effort. I was hoping this could help her, but given her gait it's unlikely.

Re:By using it

[slashdot_commentator]

But lets hypothesize that you had a need to walk 10 miles in one direction and 10 miles back. Your calf muscles aren't weakening because they're being worked, but you expend about 7% less (metabolic) energy completing the 20 mile walk.

Re:I don't need Bo Jackson legs

[plover]

And you wouldn't get them from this. This reduces the amount of exercise your muscles do, not increases it.

Re:First Step toward MANTIS

[Half-pint HAL]

I'm not sure it does anything -- the original article was published on Wednesday. Also, there's no video....

Wow...Not one post...

[RavenLrD20k]

Not one poster calling this out as the April Fool's day crap article it was meant to be (posted to the firehose 2 days late I might add). Now, I'm all for the meta joke that may be happening here and whatnot, but I would have thought there would have been at least one of y'all flipping their shit over this before now, calling the Slashdot Eds lazy or stupid as hell for putting the readership through a day of nothing but an overdone joke of fake sci-fi news post after fake sci-fi news post of original content; completely ignoring the firehose that had some pretty damn good joke articles, like this one, for a whole day. Then they just come back to their lazy ass routine of "Oh, this looks good, who cares about fact-checking the actual article or even THE ARTICLE DATE, looks legit, greenlight!"

Now I could be wrong and the Eds are just getting one last AFJ troll on us. Could also be that the Eds are clueless to their fuckup, and the readership is just trolling them by having the legit conversation. It could also be that they attempted to troll us, and the /. community meta-trolled them by playing along that this is supposed to be legit. Another possibility could be that Zothucla trolled every damn one of us (either accidently or on purpose) and the Eds and the community are fucking clueless (as ever). Then, all of the above could just be trolling those of us who see the joke unfolding and the first one who spouts off anything about it Loses the Game(tm)!

Well, I just lost the Game, and thus, so did everyone else reading this post. Have a great Friday!

Re:Wow...Not one post...

[RavenLrD20k]

Actually, I was wrong. Longjmp did attempt to subtly inform everyone that this is an AFJ by pointing out that the original article appeared on Nature on April 1st... but it seems that the subtlety was lost on the crowd.

Re:By using it

[mrchaotica]

Better yet, let's hypothesize that the place you needed to go was too far away to reasonably walk to without this device, so you drove a car there instead. Now, with the device, you can walk farther than you were willing to walk before, causing a net increase in exercise (and a more eco-friendly commute).

Re:"Unpowered" Energy ;)

[NeoMorphy]

Gravitational potential energy converted to elastic potential energy which is then reversed. Heat is generated during the process, but probably not as much heat from the normal walking process.

Your argument about adding weight to a system causing it to use more energy would make sense if you were always going uphill. If you are still at ground level that probably isn't true. The Prius is heavier than a normal car(additional weight of battery and electric motor), but it still ends up being more fuel efficient than any other mid-size car.

My issue with using such a device is that walking is great exercise and making it easier would reduce the benefits. It would also make your ankles weaker. I used to love wearing high-tops sneakers until I noticed this problem.

Re:I don't need Bo Jackson legs

[BarbaraHudson]

A better way would be to just lose 10 pounds. Not only is there that much less weight to carry around, but you'll increase your endurance, etc.

Re:"Unpowered" Energy ;)

[BarbaraHudson]

A biological system expends chemical energy to maintain a static position. Sure, sitting expends no energy -- assuming the person is modeled as a perfect sphere...

For a lot of people, a sphere is a pretty good first approximation.

I'd prefer...

[nospam007]

...a system that would store the energy for a couple of hours and use that to walk me home when I'm drunk.

Or stop wearing energy stealing shoes

[trout007]

The cushioning in modern shoes steals energy from your gait. If you go barefoot or wear shoes like flip flops or business shoes with no padding and your calves develop to the point where you have your own spring.

Here's a picture of the exoskeleton in use

[Chris Mattern]

The purpose of the device she's holding in her hands is unclear.

Re:Here's a picture of the exoskeleton in use

[Chris Mattern]

Goddamit, it ate my link.

http://images3.wikia.nocookie....

What?

[g0bshiTe]

Am I right in hearing this?

Scientists have now taken walking an activity many use for exercise and made it so we burn less energy by walking?

Re:What?

[moeinvt]

That was my first reaction as well. The only exercise most people in the USA get is walking and often it's only to and from cars or in stores.

Could be useful for military personnel on long treks or for hiking the Appalachian trail or something. IANA physiologist, but my guess would be that this could not only reduce energy usage, but could also prevent or delay the onset of muscle cramps.

Otherwise you're right, most people would prefer to burn more energy while walking.

Re:What?

[DigiShaman]

Anything that can cause muscle atrophy in the legs is not something I want.

Makes walking easier?

[PPH]

I'm going to wait for the Baron Harkonnen model to come out.

Re:I don't need Bo Jackson legs

[Coren22]

From the captions on the pictures, it says it reduces the energy used for walking by 7%, I am thinking this would be great for backpacking. It would reduce the amount of energy you expend and allow you to carry more weight.

Re:"Unpowered" Energy ;)

[Coren22]

Have you ever climbed a mountain, or gone backpacking? If you could go 7% farther in a day for the same energy input, or carry 7% more weight, it would be damn useful.

Not everything is about exercise, sometimes you want to reduce your energy usage.

Re:"Unpowered" Energy ;)

[dinfinity]

Also: muscles just aren't amazing as springs.
They're ok, but not as good as proper springs (ask the IAAF and Oscar Pistorius -- Philosoraptor: "Maybe we should give the elderly these blades instead of lower legs? Will old people lead the cybernetic revolution?").

It's like comparing a car with regenerative braking to one without (yes, also a car analogy). It's easy to see that the energetic cost of any added weight is easily offset by the reduced loss of energy to friction.

It remains to be seen ...

[Rambo Tribble]

... the physiological consequences of having a stride that is stronger than you are, particularly after the devices come off. Might be a good time to get that degree in podiatry.

Re: First Step toward MANTIS

[kheldan]

Firefighters and military need to be at their peak levels of physical fitness, not allow their ankles to get weak because they're using a form of crutch. Devices like this should be limited in use to people who are injured or disabled in some way, not healthy people who can and should regularly exercise in order to maintain (or improve) their overall health.

Re:"Unpowered" Energy ;)

[volmtech]

The elderly and partially disabled need leg supports that keep you from falling. Occasionally my right leg gives out. I go to take a step and BOOM, I'm on the ground. It happens often enough my reflex is to put my hands to my chest and roll to land on my right shoulder. It's hard to get some exercise and yard work done when you spend a fair amount of time inspecting your lawn at eye level.

Re:I don't need Bo Jackson legs

[BarbaraHudson]

It only works while walking on level ground, so probably not all that good for backpacking.

Re: First Step toward MANTIS

[Immerman]

They decrease metabolic cost by 7% - suggesting that they would allow a perfectly healthy and fit person to carry ~7% more total load than they otherwise could without exhausting themselves. For a 200lb soldier capable of carrying another 200lb on his back, that's an additional ~24lbs they could carry essentially for free. Or alternately, break these out when carrying your normal load on a long forced march into enemy territory, and you can go at least 7% further, or reach your destination with extra energy reserves instead of being fall-down exhausted.

Let me guess - you're also opposed to power steering and brakes - and cars in general for that matter. Bicycles too I assume, after all they're radically more energy-efficient than walking, rather than a paltry 7%.

As someone who's been getting into ultralight backpacking, I can attest to the amount of difference 10lb in your pack can make. Cut ten pounds from my pack and I can travel probably 50% further in a day, and enjoy myself the entire time rather than simply plodding along exhausted for half of it. My instantaneous power output is a bit lower, but the total amount of energy I burn is much higher - I call that an unmitigated win for exercise.

Re:First Step toward MANTIS

[Immerman]

Nice catch, but I wouldn't be at all surprised if it's completely legit - the human walking cycle is actually extremely inefficient, and it sounds like they're essentially borrowing lessons from kangaroo anatomy, who are able to run/hop long distances at high speed thanks to the fact that their ankle tendons are extremely elastic and can store the energy absorbed during landing and release almost all of it back into the next jump - essentially they exert very little energy to maintain speed, and are about as efficient at overland travel as it's possible to get without having wheels.

In related technology I've seen some very interesting DIY passive "cybernetics" involving spring-steel "foot extensions" that allow people to run 15-20mph without getting winded - and not just any people, we're talking about the sort of cool geeks that think designing and building bio-mechanical enhancements is a fun way to spend time. And, come to think of it, it seems like many of the amputee runners in the Paralympics can dramatically outperform their foot-wielding Olympic peers thanks to much more efficient designs of their passive prosthetics.

Re:I don't need Bo Jackson legs

[Coren22]

I don't see that in the article at all, in fact one of the pictures shows a guy wearing one walking up stairs.

The device reduces the energy use by replacing the calf muscle keeping tension on the achilles tendon with a spring and mechanical clutch mechanism, so it should work on any kind of terrain where you have to keep stable while a foot is on the ground. The clutch apparently disengages when you lift your foot so that it doesn't pull your toes down which would interfere with your walking.

Re:Excellent!

[Immerman]

I prefer lifting, myself. Preferably a pair of pints of oatmeal stout - that higher specific gravity means I'm burning more calories every time I raise my glass.

Re: First Step toward MANTIS

[sjames]

They need to train without them but use them when actually doing their job.

Re: First Step toward MANTIS

[HornWumpus]

Ultralight backpacking? That's just regular backpacking for those who spend mega bucks to shave grams right?

It's not like everybody else has been carrying the rocks to form a fire circle, just in case there aren't any at the camp site.

Re: First Step toward MANTIS

[Immerman]

Well, you can certainly go that way if you like - I'm more the budget DIY type myself. Mostly it's just about actually paying attention to the cost-benefit ratio of what you're carrying: I can now get everything I need for a cozy warm and comfortable multi-day hike into a ~10lb day pack now, instead of the 20-30lb pack I used to carry. I could easily cut that in half again if I cared to spend $$$ on titanium sporks, cuben-fiber tarps, etc, but I don't spend enough time camping for it to be worth it. Hell, my $20 Walmart sleeping bag is most of the weight (and bulk) on it's own, but it gets the job done well enough that I feel no need to spend 10x as much for a nice down or high-tech alternative.

But yeah, gram-counting does definitely come into it - a few grams here, another there, and you'd be surprised just how quickly you're talking about several extra pounds.

Re:By using it

[slashdot_commentator]

Not disagreeing with you, but I was looking more towards situations in meatspace. Such as areas that are not accessible by roads. Which would be rural villages not in the US, or "wild" areas like Alaska or Northern Canada.

Re: First Step toward MANTIS

[uninformedLuddite]

you need a backpack for a multiday hike?

Re: First Step toward MANTIS

[uninformedLuddite]

It's a PC term to refer to the disabled. Let's say you wer born with no arm or legs and you had hydrocephalus(is that the word). You would have other abilities to a standard person. Apparently in some fields you would be like a superhuman in comparison.

Re: First Step toward MANTIS

[Immerman]

What can I say, I prefer to do my camping in style.

Re: First Step toward MANTIS

[HornWumpus]

I don't know any second time backpackers who don't do the weight-benefit thing.

If you are backpacking with that light a pack you are doing it in Hawaii. Water weights about 8lbs/gallon (take that metric dweebs).

So ultralight backpacking==backpacking on golf courses, getting drinks from course girl? People that go into the desolation wilderness with 10lb packs are soon statistics.

Re: First Step toward MANTIS

[Immerman]

Sure, there's just many places on the weight/benefit scale that you can choose to stop, and most people shed a lot of weight after their first trip or two - some people just choose to continue the trend even further - I suppose a lot of it boils down to whether you see the camping or the hiking aspect as being the really fun part. Me, I like walking all day without trying to reach a destination, so I try to avoid carrying a pack that interferes with that.

As for water - there's these things called rivers and springs, maybe you're heard of them? They flow all over the place, and provide convenient water to allow people and animals to survive? Basically, if there's animal life, there's accessible water, somewhere - you just have to know how to find it.

Re: First Step toward MANTIS

[HornWumpus]

There is almost always water somewhere. Don't backpack west of the Mississippi and expect you can always find water. 99% of the time you'll be right, the other 1% will be a very bad day.

But my point is about the harshness of the conditions. A 10 lb pack can get you killed anyplace you might need shelter.

Walking is cool and all. But backpacking is about your full outdoors skill set. Ever backpacked up, dug a snowcave, slept in it, then walked out? With a 10 lb pack? (It ought to be possible, but if you fuckup, you die.)

Re: First Step toward MANTIS

[Immerman]

Well yeah, you do want to basically know the water situation in the area you're traveling in, or hike along rivers (my personal preference).

And sure, I wouldn't go winter camping without more serious gear, but then I rarely want to go camping in the winter anyway. As it is most of that 10lbs is (loosely) shelter - I don't choose to sleep cold, wet, or on the ground. And living in the desert, overnight temperatures can unpleasantly cold even in the summer.