Artificial Muscles

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HS

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Artificial Muscles
« on: February 09, 2021, 07:14:33 am »
Has anyone tried wires/equivalent mechanical linkages, with beads/wheels on them to dramatically reduce friction, twisted around a cylinder? Do you think that would work?

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infurl

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Re: Artificial Muscles
« Reply #1 on: February 09, 2021, 07:49:12 am »
It might work but you might not need the wheels or beads, some kind of lubricant might do just as well if the wires were covered by an outer layer somehow.

Interestingly I saw an article this morning on a new kind of artificial muscle that the inventors claim outperforms natural muscles in terms of speed, strength, and efficiency by a factor of ten! There's probably a catch though, maybe they wear out too fast.

https://spectrum.ieee.org/tech-talk/biomedical/bionics/nanotube-bionic-muscles-are-10-times-stronger

They work using an electrochemical process to twist and untwist carbon nanotubes.

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WriterOfMinds

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Re: Artificial Muscles
« Reply #2 on: February 09, 2021, 05:26:04 pm »
Has anyone tried wires/equivalent mechanical linkages, with beads/wheels on them to dramatically reduce friction, twisted around a cylinder? Do you think that would work?

It sounds like you're talking about a belt or pulley system of sorts, but still motor driven, rather than matter that contracts and extends. That true?

I've used threads or fishing lines wrapped around a motor-driven rod as a linkage for a rotating sphere before, and it works reasonably well: http://writerofminds.blogspot.com/2013/12/eyeball-details-mechanical.html

I also went on a contracting material spree about five years ago, trying out artificial muscles made of nylon. http://writerofminds.blogspot.com/p/nylon-fishing-line-artificial-muscle.html There were also big claims made about these re: power-to-weight ratio or something like that. I got them to work, but eventually abandoned them because they just didn't seem practical enough. If you power them electrically, they're huge current hogs; they're slow, especially on the extension side of the cycle; and worst of all, they don't seem to hold their shape over time.

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HS

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Re: Artificial Muscles
« Reply #3 on: February 09, 2021, 07:29:41 pm »
What I’m thinking is, basically if those stripes on a barber pole were strings, (only with beads/bearings on them to allow for rolling contact). One possible version of this could have all the strings attached to a collar at one end, and fastened to the cylinder at the other end. Then if the collar was twisted along the axis it shares with the cylinder, the mechanism (I imagine) would produce a very smooth mechanical advantage, contracting/expanding along the axis. Not sure how I would classify this… Seems like some kind of inline pulley / self contracting matter hybrid. Axial pulley? 

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WriterOfMinds

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Re: Artificial Muscles
« Reply #4 on: February 09, 2021, 09:01:38 pm »
I think I have the right picture in mind now.

I figure it could work. A "muscle" can only pull/release, not push, so I think you would either need a differential pair of them, or need to have it working against e.g. a spring return.

If you need powered movement in both directions, I might prefer a lead screw. But this could be cheaper and easier to manufacture yourself.

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HS

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Re: Artificial Muscles
« Reply #5 on: February 09, 2021, 10:39:26 pm »
If you need powered movement in both directions, I might prefer a lead screw.

That should actually work well for my current aplication, I'll definitely be saving that for later in case I need it.

The exciting thing about this axial pulley idea, is that I have almost no clue about how well it might work, or what kind of variations on the basic premise I, or others, might be able to develop.

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MikeB

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Re: Artificial Muscles
« Reply #6 on: February 10, 2021, 06:52:14 am »
Kengoro and Kenshiro from the University of Tokyo have worked on artificial muscles for a few years.

Solid tendons and motors rather than actually simulating muscles but it works great. Many videos of them doing pushups/situps, and with aluminium bones they only weigh 100kg for a full size adult.

Quote
To imitate the very complex human anatomy made up of approximately 640 muscles, the scientists equipped Kenshiro with the most important human muscles: 50 in the legs, 76 in the torso, 12 in the shoulder and 22 in the neck. This robot has the greatest number of muscles ever installed in a humanoid robot. Kenshiro's 160 individual tendon-controlled “muscles” make many humanlike movement patterns possible.

https://www.robotics.org/content-detail.cfm/Industrial-Robotics-Tech-Papers/Kenshiro-Strong-Robot-with-160-Muscles/content_id/5535

 


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