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useing bs2 with flexinol muscle wire? — Parallax Forums

useing bs2 with flexinol muscle wire?

iamdenteddiskiamdenteddisk Posts: 66
edited 2014-11-05 03:44 in Robotics
is it possible to use the bs2 with muscle wire in a project?
is it documented ?
if not can we design·or post here a single working muscle circuit?


Post Edited (iamdenteddisk) : 6/17/2008 12:05:49 AM GMT

Comments

  • J. A. StreichJ. A. Streich Posts: 158
    edited 2008-06-17 00:51
    iamdenteddisk said...
    s it possible to use the bs2 with muscle wire in a project?
    Yes, it is possible; I don't think it's been done though. Muscle Wire however is apparently hard to work with. For 12cm, use 3 volts (read: you'll need limiting resistors) and only for 2 second contractions or you'll burn the wire out.
    iamdenteddisk said...
    is it documented ?
    Not that I know of.
    iamdenteddisk said...
    If not can we design or post here a single working muscle circuit?
    I suppose the members of the board could help you figure it out, but you'd need to tell us what you're trying to do, the level of contraction you need and the width (the diameter) which will determine the amperage you need. It's not a one time thing as the diameter and length of the wire change the voltage and amperage needed. For most applications a tradition actuator, motor, servo, etc. would be better. What specifically are you trying to do?
  • allanlane5allanlane5 Posts: 3,815
    edited 2008-06-17 01:40
    I think "muscle wire" is kind of slow, too.
  • iamdenteddiskiamdenteddisk Posts: 66
    edited 2008-06-17 01:40
    well mostly I wanted to document a single muscle circuit like a schematic even if it is ascii characters I have ordered some of the strands to lab naturaly robot makeing is the direction. im prety good with electronics but novice stamp user.
  • FranklinFranklin Posts: 4,747
    edited 2008-06-17 01:59
    You will need a higher current than the stamp can provide by using a transistor or mosfet of appropriate size.

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    - Stephen
  • iamdenteddiskiamdenteddisk Posts: 66
    edited 2008-06-18 01:53
    good to see some input comeing·about this ,Keep em comeing and I will edit it all into a document .Though I know I havent spent as much time·on this as usual lately because im working on bugbot upgrades·, researching this topic will take focus to weed out the wild stabs and misinformation from a good working example,·I will get some free time to devote to it soon and I will lab the muscle wire with a bs2 soon as it arives and document all findings my hope is to create one of those everything you need to know "pdf's" on the topic wich can then be hosted here if welcome·or my webpage for free download .

    this is a topic started by me as a pre-research chance to fish for leads info/schematic's leads about·useing the bs2 to control flexinol muscle wire as actuator's for robot projects.

    so far we have heard a few characteristics /unverified..

    slow in action

    3v for 12cm

    2second contractions

    the statement·about current is ignored on the grounds that the "flexinol will work" though be-it indirectly meaning "support circuits ,external power or relay's,switch's may be needed·needed",this is normal when connecting devices and should in no way rule out the bs2 as a viable controler.



    still not enough to make out·a clear picture. but these will be verified or flushed thanks guy's keep em comeing..


    Post Edited (iamdenteddisk) : 6/18/2008 2:05:30 AM GMT
  • ercoerco Posts: 20,255
    edited 2008-06-18 02:07
    Nitinol/flexinol muscle wire is temperamental stuff. Very power hungry (high current demand) for the tiny work output you get. Also·very demanding·to make reliable mechanical connections. No room for mechanical slop in your linkages, the contractions are so small that any clearance variation in different robotic arms & legs will be immediately apparent. Easiest use of raw wire is simple non-precision stationary displays like slow-flapping wings that run off a big battery or wall wart (AC adapter). Premade assemblies (AKA electric pistons, see http://www.robotstore.comhttp://forums.parallaxinc.com/download/EPiston_Instr_V12.pdf) reduce the demand for mechanical precision, but get expensive pretty quick.

    Nitinol is the classic solution in search of the right problem.




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    ·"If you build it, they will come."

    Post Edited (erco) : 6/19/2008 3:42:53 PM GMT
  • iamdenteddiskiamdenteddisk Posts: 66
    edited 2008-06-24 22:42
    how about useing a potentiomiter in the circuit to control the amount of contraction like min-max flex of a muscle ? useing the 12cm length like above.................................


    ahha..now where getting somewhere useing pwm on an analog device this is getting intresting thanks mike ,though it is analogous to throwing water on a greese fire it actualy makes perfect sense ,to me any way ..but useing pwm is a current limiting Resistor still required?
    IM·imagineing the liner fall like that of a discharging capacitor as current switches on the Voltage will rise to peek then fall starting at the end of a pulse wich then is met with the following on pulse like a triangle waveform across the flexinol
    but as the tepurature rises the resistance of the wire falls ...um I think im getting confused here..







    .can anyone give schematic with 12cm at 3v im lost at the value of (R)?


    Post Edited (iamdenteddisk) : 6/25/2008 6:17:52 AM GMT
  • Mike GreenMike Green Posts: 23,101
    edited 2008-06-24 23:19
    I wouldn't recommend using a potentiometer because of the amount of current involved. More useful is pulse width modulation where a MOSFET or junction transistor switch is fully on or off and the on/off ratio lets you (roughly) adjust the contraction by affecting the wire's temperature.
  • fuichrisfuichris Posts: 26
    edited 2014-11-04 20:48
    erco wrote: »
    Nitinol/flexinol muscle wire is temperamental stuff. Very power hungry (high current demand) for the tiny work output you get. Also·very demanding·to make reliable mechanical connections. No room for mechanical slop in your linkages, the contractions are so small that any clearance variation in different robotic arms & legs will be immediately apparent. Easiest use of raw wire is simple non-precision stationary displays like slow-flapping wings that run off a big battery or wall wart (AC adapter). Premade assemblies (AKA electric pistons, see http://www.robotstore.comhttp://forums.parallaxinc.com/download/EPiston_Instr_V12.pdf) reduce the demand for mechanical precision, but get expensive pretty quick.

    Nitinol is the classic solution in search of the right problem.




    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·"If you build it, they will come."

    Post Edited (erco) : 6/19/2008 3:42:53 PM GMT

    Hi erco,
    I'm digging around still trying to make my flower petals move, and wanted to use Flexinol as well as the petals will be slow moving and the petals are only 2cm small each. I'm using the Homework Board and know it needs more power, but I'm not sure how to add more power and still use the board. I know MOSFET is a key, but I'm not sure how to tie it all together on the board. BRAIN DISCONNECT. See pic. (I was going to also replace the 9v battery with a 9v AC adapter as well cause I wanted it to run for months). HELPPPPPPP :D
    C.
    IMG_7339.jpg
    IMG_7339.jpg
    1024 x 768 - 129K
  • Ken GraceyKen Gracey Posts: 7,387
    edited 2014-11-04 20:59
    On the question of whether or not it's been done, it certainly has. I've done it to make a little Stiquito robot walk around - perhaps 15 years ago.

    I was impressed with this material (also called shape memory alloy, I think) at the time until I started to understand the current needs and mechanical design needed to make a little movement have visible results.

    It's interesting to play with and probably lends itself well to organic types of robotic projects, but it's also a bit of a project to create the mechanics you want to move around.

    Ken Gracey
  • Mike GreenMike Green Posts: 23,101
    edited 2014-11-04 21:24
    Nuts and Volts Column #6 gives some examples of using a BS2 and BJTs (bipolar junction transistor) to switch high power. MOSFETs are also very good, but there's not a nice neat article discussing them. Since shape memory wire is purely resistive, you don't need the diode across the load the way you do with a relay or motor. A 9V battery or even a 9V AC adapter is simply incapable of providing the amount of current needed. Read the datasheet for the shape memory wire you plan to use to get the resistance per unit length so you can figure out the voltage you need to get the current specified in the datasheet. Remember also that the heat produced that causes the wire to contract has to go somewhere for the wire to cool so it can stretch out again.
  • PublisonPublison Posts: 12,366
    edited 2014-11-05 03:44
    Your duplicate post has been deleted.

    Please read the forum guidlines:

    http://forums.parallax.com/showthread.php/134682-Forum-Guidelines
    No cross-posting:
    Cross-posting is: 1) submitting a post to one forum or thread, and then submitting a second linking to the original post (without changing content or intent), or 2) creating an identical post in more than one forum or thread. When the same content is found in more than one post, even under different subject lines, the forum moderator will remove one (or more) of the redundant posts.
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