
Origami-inspired soft artificial muscles - lithander
https://wyss.harvard.edu/artificial-muscles-give-soft-robots-superpowers/
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NickHoff
I did my PhD with this group (Rob Wood). When I was there, these kind of
actuators, and the robots you would put them in, were just getting started.
It's great to see how far they've come.

One of the great benefits of these soft actuators is that you can embed them
in soft structures and then get smooth movement in multiple directions.
Instead of a rigid robotic arm with a few degrees of freedom, you could build
something like a snake or an elephant trunk.

Another exciting area of research (my focus) is that since these actuators are
fairly cheap, you could make lots and lots of robots with them. Think
thousands. If you had a swarm of 1000 small robots, each of which has minimal
power and sensors, what would you do with it? How would they coordinate their
behavior? How would they communicate? For that matter, how would you even turn
them all on? Swarm algorithms are fun to think about on robots, but are also
useful for other problems out in the normal world.

(Don't focus on the "1000x" claim. It's true depending on how you measure, but
it's not the exciting part.)

~~~
YeGoblynQueenne
Well, since you've worked with those kinds of actuators I hope you can clarify
something I wasn't sure about in the article: can the same muscle perform
different actions? For example, could you have a muscle that can bend to the
left, then to the right of some central line?

I'm asking because the statement [edit: in the article] that "designing how
the skeleton folds defines how the whole structure moves" makes me think that
perhaps the range of motions each muscle can perform is limited by
construction.

Ahem. That's not to downplay the obvious usefuleness of such a device. As far
as I'm concerned t's the first time in ages I find a robotics piece of news
cool.

~~~
NickHoff
In general no, single actuators move in one dimension and then only in one
direction. In humans we have muscle pairs, one contracts to open the joint and
the other contracts to close the joint. Of course you can do the same thing
with artificial actuators, but you're right, the really interesting stuff
happens when you have lots of "actuators" (like a sheet that has a hundred
individually inflatable cells) or the material that the actuators are embedded
in folds in an interesting way. The properties of the skeleton have as much to
do with the dynamics of the robot as the actuators do.

~~~
YeGoblynQueenne
Thanks for answering. I looked at the video again and I can see that a couple
of setups use multiple muscles- that's what you're talking about I think. I'm
guessing that it's going to be a lot easier to wrap a hundred individual
muscles of this kind around an artificial skeleton than it is with "hard"
ones.

I wonder also what all this means for more, let's say, traditional robots-
like the ones we often see from Boston Dynamics. I guess it's still early to
say but if I understand this correctly, people can now make cheap, light
robots. Where does that leave heavy, expensive ones?

It's not a rhetorical question- Ferrari and McLaren didn't hang up their
spanners just because Toyota and Datsun sell lots of cheap cars...

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sova
This is tremendous and probably what all robots that interact with humans will
look like in the next 50-100. Affordable flexible membranes able to grasp and
grapple with our real world, and also gentle enough (when programmed
correctly) to not harm humans and other beings, this is the future right here.
Very exciting. Focus on the information and less on the headline, guys.

~~~
gene-h
I am extremely doubtful of this future. A big part of the reason we are
considering soft robots today is safety, that if the robot hits a human it
won't hurt them. If we can make robots smart enough that they never hit humans
this is no longer a problem. Another reason is making things compliant so that
we can grip objects because we have yet to figure out grasping. If we solve
grasping, we no longer need compliant grippers.

In addition, pneumatics which this work focused on, are probably not the
future. Pneumatics are not that efficient, are noisy, and are limited by the
compressibility of air. The compressibility of air limits how fast these
devices can actuate, their stiffness, and even how efficient pneumatic systems
can get. Efficiency alone might be enough to encourage future robot makers to
use something else.

Stiffness is another compelling argument against both pneumatic robots and
soft robots. The max rate at which a robot can do stuff and react to things is
dictated by its resonant frequency and mass. Sure we can make our robot very
light, but we aren't going to be able to change the mass of things we desire
the robot to manipulate. So it is still desirable to have robots with higher
stiffness.

Really, a number of different technologies could make this obsolete within 50
years. For example, electric artificial muscles, slightly better rotary
electric actuators along with rapid robotic assembly enabling stuff to have
huge number of moving parts, or even advanced nanotechnology.

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fallingfrog
It looks like this is some kind of pneumatic system, and IMHO if you're
calculating strength/weight you would need to take into account the weight of
the air compressor, to have a fair comparison with biological muscle. Not to
mention the fact that air compressors need to have an energy source, and are
quite noisy.

~~~
keenerd
The "big new thing" about this is that it doesn't use compressed air the way
traditional air muscles do. It doesn't use _compressed_ air at all.

You're probably going to say that vacuum pumps are noisy/heavy next. But this
doesn't need traditional high-grade vacuum pumps, very low grade will work.
And of course it is entirely moot for industrial machines that stand in place.

From what I can tell the trick comes from the pleating to massively increase
surface area, giving atmospheric pressure more to work with.

I've been working with robotics (as a hobbyist) my entire life. This is the
most exciting thing that I've seen in a while and I'll be building prototype
knockoffs all week.

~~~
DennisP
If you get something working I'd love to see a how-to article.

~~~
cr0sh
Heck, you could probably replicate it somewhat with a plastic baggie, some
bits of cardboard, and a straw. Add some duct tape and hot glue, and you'd be
set.

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xchaotic
The 1000x comparison is silly - in a straight up lifting of things, a simple
steel wire can probably lift 100000x times it's weight. The tech has it's uses
and they should highlight the flexibility rather than perceived strength...

~~~
tomp
A steel wirte isn't _lifting_ anything, it's just _holding_.

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mlevental
i don't understand what this means. you understand that g = 9.81 m/s^2 ...
every second? the difference between colloquial lifting and just holding is a
matter of applying on the order of just 1% more force.

~~~
SketchySeaBeast
So if we took away 1% of that 1000x it's own weight it would be able to lift
it? It can't. It will never be able to. Only thing I got out of my engineering
dynamics class - ropes don't lift. Well, that and jokes about couple moments.

A lift is not a hold. A human can hold a ton of weight against gravity, but
that's not them lifting it. See the squat. You can put a huge amount of weight
on your back compared to the amount you can actually move. If you put them on
an escalator, they could probably even move a distance with it. But that isn't
them lifting it that distance.

~~~
arghwhat
A human can hold several loaded shipping containers stacked upon each other
against gravity.

The human will be very flat and leaking all over, but it will be holding the
containers.

~~~
SketchySeaBeast
"I guess he kind of bench pressed that steam roller... kind of."

~~~
arghwhat
He lifted it _several_ millimeters off the ground!

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eggy
I recall when I was building animatronics in the 90s there was a pneumatic air
bladder "muscle" at the time wrapped in stainless steel weave basket. So
instead of using a rigid cylinder with rod, when you inflated the bladder its
length contracted. You could make an arm bend and the appearance of a bulging
bicep! Somewhat similar principle, but animatronics doesn't use high-volume
parts, so it never took off. These origami-inspired actuators seem really
cool!

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clickok
Neat!. I am working on artificial muscle as a side project[0], especially the
kind you can (cheaply) 3d-print. Earlier work used these sorts of soft
actuators similar to regular muscle-- you make a bunch of actuators that move
in a particular direction, strap them to a skeleton, and then activate them in
various combinations to move the skeleton.

3D printing, on the other hand, allows you to build more complex actuators
(that don't necessarily apply force in a line). Origami-inspired designs
(particularly rigid origami[1]) are related, in that you can design a
particular folding pattern and have it fold and unfold to exert force in a
particular way.

I was originally inspired by the work on artificial muscles actuated by a
phase change (liquid to gas, with attendant increase in pressure) from
Columbia[2]. Some combination of the two techniques might be better than
either alone, allowing for fast-twitch soft actuators to fill the roles that
servos stepper motors have previously occupied. Plus, they're likely to be
cheaper in general, customizable to specific tasks, and probably safer in
situations where humans might get in the way of the robot's motion.

\----------

0\. Most of the time I am working on reinforcement learning theory, and so
building an actuator with difficult-to-model dynamics seems strange. _However_
there's a lot RL could offer here, either learning how to control those
dynamics from scratch or refining an existing model.

1\. Wikipedia and its related/external links have a good overview:
[https://en.wikipedia.org/wiki/Rigid_origami](https://en.wikipedia.org/wiki/Rigid_origami)
If you just want a cool example of What Rigid Origami Can Do For You, check
out:
[https://en.wikipedia.org/wiki/Miura_fold](https://en.wikipedia.org/wiki/Miura_fold)

2\. See the press release: [http://engineering.columbia.edu/news/hod-lipson-
lifelike-rob...](http://engineering.columbia.edu/news/hod-lipson-lifelike-
robots) and the associated paper:
[https://www.nature.com/articles/s41467-017-00685-3](https://www.nature.com/articles/s41467-017-00685-3)

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juanmirocks
I cannot stop but recalling the last prodigy of Boston Dynamics.

Paraphrasing Elon Musk's words: This is nothing. In a few years, ...

[https://twitter.com/elonmusk/status/934888089058549760](https://twitter.com/elonmusk/status/934888089058549760)

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cdancette
They are basically inflating and deflating balloons filled with some flexible
structure.

So 1000x might not be that impressive, because they are very lightweight.

And I guess it requires a big pumping device in addition to the muscle (which
weight is not included in the calculation, but certainly should be).

~~~
blacksmith_tb
The weight of the compressor is important, but one compressor could be driving
lots of 'muscles' via opening and closing valves, so it isn't completely
disingenuous. It's analogous to, say, a robot with six motors, all powered
from a single battery.

~~~
arghwhat
A compressor driving more of these hydraulic actuators need to be larger and
heavier than one driving one hydraulic actuator.

Rather than battery and many motors, its more like motor with many
transmissions and clutches. Vacuum is also a bad choice of medium... It
requires stronger pumps, stronger hoses, better seals, etc.

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wellboy
So how much is that compared to a human. A 3kg biceps can lift 30kgs of
weight, so artifical muscles are 100x stronger than human's?

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grkvlt
FYI, the associated paper from PNAS is
[http://www.pnas.org/content/early/2017/11/21/1713450114.full...](http://www.pnas.org/content/early/2017/11/21/1713450114.full.pdf)

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bawana
I wonder if this would make a better penile prosthesis for erectile
dysfunction...

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Numberwang
"Artifical muscles can also lift, grip and twist objects."

I want to see it crush as well.

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bjd2385
Reminds me of cell flagella.

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Digit-Al
So when do I get my Doctor Octopus style robo arms? :-)

