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Muscle from fishing line — Parallax Forums

Muscle from fishing line

prof_brainoprof_braino Posts: 4,313
edited 2014-02-24 23:04 in General Discussion
See this? It was on Hack A Day, now it in the newspaper.

http://www.palmbeachpost.com/news/news/national/researchers-make-artificial-muscle-fishing-line/

Ferb, I know what we're going to do today!

http://hackaday.com/2014/02/21/

So, would we heat the fish line with parallel nichrome wire or what? I think I have a Stickito kit that wants to play....

Comments

  • Clock LoopClock Loop Posts: 2,069
    edited 2014-02-23 00:28
    What if you microwave it? Or shoot a high watt laser at it.

    Paint the wire black and shoot a laser at it?

    Find a pigment that heats up when exposed to uv or ir...
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2014-02-23 07:21
    Hi Professor;
    I can't read the original article.
    The hackaday reference states the work done is 5.3kW/kg. However, this makes no sense as kW is a unit of power.
    I suspect it should be 5.3kWhr/kg.

    The comparison to muscle is a bit problematic though. Muscle is powered chemically and moves electrolytically. This process is quite efficient.
    The Fishing Line muscle is powered thermally and I suppose moves by thermal expansion. I doubt it is very efficient.
    It is essentially a Brayton Engine.

    The problem: since the Nylon itself has thermal mass heating this mass is wasted energy. Only the energy causing expansion is useful.

    A very good example of a BAD DESIGN is the Wally Minto's Wonder Wheel. This link goes to my friend Steve Baer's patent for a similar device with much better efficiency. I put Minto's wheel in with Steve's patent as Minto didn't patent the wheel.

    I don't want to be a wet blanket on interesting ideas but some may just be impractical, like the Minto wheel.

    Duane J
  • RDL2004RDL2004 Posts: 2,554
    edited 2014-02-23 10:02
    Science Magazine wrote:
    Abstract

    The high cost of powerful, large-stroke, high-stress artificial muscles has combined with performance limitations such as low cycle life, hysteresis, and low efficiency to restrict applications. We demonstrated that inexpensive high-strength polymer fibers used for fishing line and sewing thread can be easily transformed by twist insertion to provide fast, scalable, nonhysteretic, long-life tensile and torsional muscles. Extreme twisting produces coiled muscles that can contract by 49%, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram of muscle weight, similar to that produced by a jet engine. Woven textiles that change porosity in response to temperature and actuating window shutters that could help conserve energy were also demonstrated. Large-stroke tensile actuation was theoretically and experimentally shown to result from torsional actuation.

    I guess they were trying to compare the power to weight ratio and just worded it wrong.

    http://www.sciencemag.org/content/343/6173/868
  • doggiedocdoggiedoc Posts: 2,241
    edited 2014-02-23 10:30
    So....

    If you somehow embedded a small wire into the fishing line to apply current to heat the wire, you could induce contraction electrically.

    Or not.
  • jazzedjazzed Posts: 11,803
    edited 2014-02-23 10:51
    doggiedoc wrote: »
    So....

    If you somehow embedded a small wire into the fishing line to apply current to heat the wire, you could induce contraction electrically.

    Or not.

    Hi Doc! We've missed you.

    "Or not." :) Ya, I was thinking of "Burning Man" for some reason.

    I tried the Nitinol thing long ago ... that ate lots of batteries :)

    Bicycle brake wire is good for servos. I wonder if loose tube fiber optic cable could be used instead.
  • Beau SchwabeBeau Schwabe Posts: 6,566
    edited 2014-02-23 11:08
    Wonder if humidity would contribute a significant amount to the level of contraction?

    I would also imagine cooling attempts to relax the 'muscle' would be analogous to lactic acid buildup.
  • doggiedocdoggiedoc Posts: 2,241
    edited 2014-02-23 15:56
    jazzed wrote: »
    Hi Doc! We've missed you.
    ....
    Hey Steve, I've been around just not much to say these days I guess. This thread piqued my interest .. ;-)

    I think the video mentioned poly propylene? But I'd need to watch it again. What is the loose tube fiber optic cable made of. I just assumed it was glass.

    @Beau - I had the same thought about heat build up. Your lactic acid analogy is spot on.
  • prof_brainoprof_braino Posts: 4,313
    edited 2014-02-24 19:18
    Beau Schwabe (Parallax) wrote: »
    Wonder if humidity would contribute a significant amount to the level of contraction?.

    I saw a follow up vid where they used red and blue dyed water to heat and coole the filament to produce contraction/relaxation. So moisture doesn't affect it to the extent of hampering the function.

    It occurs to me that the first tube volume of liquid would be the same actuation temperature, and might be recycled.

    Also 1 or 2 volumes of liquid would be needed to reach the opposing target temperature. Perhaps careful control of these could minimize heating and cooling of the medium. I bet one could monitor and control that with a microcontroller fairly easily.
  • Beau SchwabeBeau Schwabe Posts: 6,566
    edited 2014-02-24 23:04
    In the back of my mind I was referring to a wall mount humidity sensor, which I took apart to investigate.... inside appeared to be several "switch-back" folds of thin poly propylene amounting to a few feet of material. As the humidity varied, the combined effort of the total length created a measurable/detectable output that controlled the wall unit.

    Based on that led me to the question .... "Wonder if humidity would contribute a significant amount to the level of contraction" ... if not for repeatability in "muscle" control
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