Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Muscle Wire

Status
Not open for further replies.

MrJammin

New Member
Has anyone used the material they call "muscle wire" in any projects? Muscle wire are the strands of alloy that contract when heated(which can be done by passing a current through them).

I was wondering how practical these wires are to work with. They look very interesting and I could manage making some kind of robot with them, but I want to make sure the material is reasonable to work with and has no striking disadvantages.
 
MrJammin said:
Has anyone used the material they call "muscle wire" in any projects? Muscle wire are the strands of alloy that contract when heated(which can be done by passing a current through them).

I was wondering how practical these wires are to work with. They look very interesting and I could manage making some kind of robot with them, but I want to make sure the material is reasonable to work with and has no striking disadvantages.

Foxboro Co. used that wire to drive chart pens on process control chart recorders. Worked well, accurate and held calibration very well. I recall having to replace a 'muscle wire' once. The procedure had you pre-tension the wire by holding it vertical, clamping one end in it's assembly and holding the assembly/wire vertically and then hanging a 6" vice grip pliers on the other end of the wire to tension it before clamping the lower end of the wire. Then the rest of the calibration was just tweeking the 'zero' and 'span' pots to get correct travel, this controlled the starting and max current that was passed through the wire. They called the assembly that contained the wire a 'motor' ;)

Anyway, cool material and I've looked for some on E-bay but have yet to purchase.

Lefty
 
What kind of 'muscle wire' are we talking about here? Bi-metal strips or the relativly modern memory alloy's?
 
I got the impression that they are not very fast. It takes time to cool and maybe to heat.
 
LeftyretroLeftyretro,
Didn't it need to be adjusted to compensate for the ambient temperature or was that done automatically?
 
Hero999 said:
LeftyretroLeftyretro,
Didn't it need to be adjusted to compensate for the ambient temperature or was that done automatically?

Well it's 25 years sense I worked with that unit and application was mostly inside climate controlled control houses, however Foxboro made very high quality and expensive equipment for the process control industry and I'm sure that they utilized temp comp in the amplifier circuit that drove the wire.

Lefty
 
Sceadwian said:
What kind of 'muscle wire' are we talking about here? Bi-metal strips or the relativly modern memory alloy's?


A special alloy, nitinel comes to mind but it's been 25 years sense I worked with it.

Lefty
 
ClydeCrashKop said:
I got the impression that they are not very fast. It takes time to cool and maybe to heat.

Yes, relatively slow, but the application to drive strip chart pens didn't require very high speed. I seem to recall that the pen could move from 0% to 100% in 2 or 3 seconds.

Lefty
 
Leftyretro said:
A special alloy, nitinel comes to mind but it's been 25 years sense I worked with it.

Lefty
The correct spelling (Nitinol) will yield more good Google hits.
I would think that it would require a lot of power compared to other types of "motors".
 
It seems to me that most applications would be better served by motors than muscle wires (especially anything of any size beyond teeny-tiny moves) and especially in mobile/battery applications. Mainly because motors are usually at last 50% efficientes and I think muscle wires are somewhere around 3%. Of course there's also the issue of lack of displacement and dependency on ambient temperatures which is "absent" in motors.

It would seem that to use muscle wire, you need to have a very specific small scale application (like the dust sensor on the mars rover or finger sized robots). But I'm talking here completely from a mobile/battery powered perspective- I think I calculated last time that to get the forces and displacement I required would have take 120V if I used long thin wire with pullets or 60A if I used shorter thicker wire with less pulleys.

However, if you have something that's tethered to a wall power source and works in something like water, you can get very interesting results like the robot lobster. It works in water and is tethered so thicker or longer wire can be used to get high forces while maintaining fast response time (due to the cooling of the water).

So things like arms, fingers, sensor pan-tilts, wheels, legs, and the vast vast majority of actuators on robots would have better performance, efficiency, cost, and simplicity than muscle wires. THe exception of course is on the legs of very very small finger-sized robots- except these robots tend not to be able to think or anything- just blindly walk forward for the most part. The thing muscle wire might find a use on is on a complex robot with lots of little things, at which point a tiny silent actuator for a minor part on the robot might come in handy. The thing that most immediately comes to mind (without the use of long strands of wires and pulleys which would result in very high currents being required, whereas thicker wire would seriously reduce response time), is something like a small light weight sensor to have movement like an eyeball in an eye socket- something like a diode-sized photodetector or a tactile antenna. Basically an application where "force" is a criteria is probably too much for most muscle wire methods.

Two silently moving antenna like a cockroach is damned cool though.
 
Last edited:
I think you're correct in your analysis DKnguyen. 'Muscle wire' seems like it would be really useful for small applications with lots of small moving parts. That's why I think I'll order some just to play around with. I'm excited at the prospect of creating a very tiny robot utilizing these wires.
 
i've played with some wire that you ca tie into loose knots, the you drop it in hot water, and it springs out of the knot?is that muscle wire?
 
A little Googling reveals that Nitinol is one member of the class of memory metals.
 
MrJammin said:
I'm excited at the prospect of creating a very tiny robot utilizing these wires.

How about this one ? :eek:

**broken link removed**
Cockroach Control System (via psychological manipulation) - Instructables
 
memory wire!! thats the one! pretty cool stuff that!
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top