motor that "bends" in reaction to current

[mscottveach]

so I know there are sensors that can sense being bent... but is there something that works in the reverse?
a material that bends in response to current? a servo that bends instead of rotates?

i am fairly new to this world so forgive any mis-use of the terms... but i have this very raw intuition that
it would be possible to make a strip of metal that was a series of smaller strips attached together..

....each smaller strip being a different metal that expanded at a different rate in response to heat?

and o if you heated them all up the net effect would be that the strip would bend in a direction?

does anything like this exist on the hobby level?

[westfw]

Yeah, sort of. Look up "Muscle Wire", "Flexinol" or "nitinol" ...
It does work by getting hot, which raises several problems:
1) it gets hot!
2) to get hot requires a significant amount of power.
3) relaxation (un-bend) time is dependent on "cooling down", which in turn is dependent on convection and other "slow" cooling effects, which can't be hurried.

[mscottveach]

thanks for reply! these are definitely the kind of thing i was imagining... i do
see your points though.. and since my project involves automatic puppets, the
"it gets hot" could be a real problem..

[westfw]

You do know that servo motors, easily controlled by something like an Arduino, now come in nearly impossibly small packages: about 20x6x6mm for a Cirrus "Micro Joule"; be prepared for sticker-shock, though. Up at about penny-sized, there is a wider variety, some of which are pretty reasonably priced, if you buy them from the Chinese hobby providers...

[mscottveach]

Actually, I didn't know about these... I mean I knew things like this existed in the world but I am very unclear on what's easily obtainable on the hobby level and what's not.
But these are sick! I just ordered some... thanks!