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Origami-inspired soft artificial muscles

wyss.harvard.edu

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Re: Origami-inspired soft artificial muscles

#41

Post by gene-h »

NickHoff wrote: post #30

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 some…

I believe soft actuators have hidden costs. While the actuators themselves may be cheap, the valving and pumps may not be.

Re: Origami-inspired soft artificial muscles

#43

Post by mlevental »

SketchySeaBeast wrote: post #21
mlevental wrote: post #13

Earlier quoted context omitted.

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.

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 am…

as someone who stalls out at the midpoint of a squat coming up very often i can tell you that locking your knees with weight on your back is not holding anything - it's putting your posterior chain under compression. my point was that something like a barbell hold (like this http://www.myfitnessstudio.co.uk/wp-content/uploads/barbell-...) is just as hard as just curling.

Re: Origami-inspired soft artificial muscles

#44

Post by [deleted] »

keenerd wrote: post #10
fallingfrog wrote: post #4

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.

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 th…

[deleted]

Re: Origami-inspired soft artificial muscles

#45

Post by NickHoff »

YeGoblynQueenne wrote: post #34
NickHoff wrote: post #30

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 some…

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 t…

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.

Re: Origami-inspired soft artificial muscles

#47

Post by NickHoff »

gene-h wrote: post #41
NickHoff wrote: post #30

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 some…

I believe soft actuators have hidden costs. While the actuators themselves may be cheap, the valving and pumps may not be.

Certainly. For what I said about the swarms to make sense, each robot must have a self-contained power source or be externally powered in a wholesale manner (generally by absorbing energy from the environment). For single (or few) robots though, you usually want the neat actuation mechanics and you're happy to pay the cost of the actuators and associated support hardware. The supporting hardware is always getting lighter and smaller though.

Re: Origami-inspired soft artificial muscles

#48

Post by gene-h »

sova wrote: post #14

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.

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.

Re: Origami-inspired soft artificial muscles

#49

Post by [deleted] »

tomp wrote: post #16
mlevental wrote: post #13

Earlier quoted context omitted.

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.

I'm not talking about force, but about energy. To hold something suspended in air, you don't need any energy. But a steel wire can't lift anything, you need to have a motor (or muscle) that actually expends energy to move the object higher.

[deleted]

Re: Origami-inspired soft artificial muscles

#50

Post by arghwhat »

SketchySeaBeast wrote: post #36
arghwhat wrote: post #23

Earlier quoted context omitted.

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.

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

He lifted it several millimeters off the ground!
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