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Animating a stuffed toy. Answered

I'm brand new to this site and hope some one can help me. I am making a fabric covered starfish that will be stuffed with a polyester fiberfill. I am wanting to animate it in that I wish the arms to move in some manner. I'm not fussy about what direction or even how much; I just want it to have the appearance of being alive. I also want to have two small lights for eyes; if they could blink, that would be cool, but if not that's fine also. I don't know a thing about what I need and live in a small town, so my resources here are little if none. Hobby store websites have been no help. I just need someone to give me some ideas of what I need and how to run wires or whatever into the arms to make them move. Of course, I'm looking for this to be battery operated. Something I can turn on and walk away from. I can adjust the size of the starfish to accomodate the equipment I need, but don't want it to be too big. I guess I want it to be as compact as possible. I saw the wonderful hand that someone built and it said that it could be done using servos(which I have no clue what they are), but that sure got my interest as the fingers moved much like I would like the arms of the starfish to move. So can someone give me some suggestions or head my in the right direction? Thanks so much!



10 years ago

Muscle wires would definitely be very cool, and have the advantage of not needing a bunch of separate motors for each arm. Of course, you still need some sort of controller to send signals to all those pieces of muscle wire.

You could make a more minimalistic design using a single electrical motor, to which you attach wires controlling all 5 arms of the starfish. Kinda like those good old radial engines for propeller planes. (In a radial engine, you turn the linear motion of 5 or more pistons into a rotating motion of a propeller through a common crankshaft - here, you're trying to turn the rotating motion of a single electrical motor into linear motion for five starfish arms.)

If you span the wire across the very bottom of each arm, the starfish will probably just rotate in place. With a more creative orientation of the wires, you could probably make it move in a straight line, or just gently writhe and wave its arms around...

The advantage of this design is that you just need a cheapo electrical motor (no need for a servo - a recycled drive motor from an old casette player would do), an on/of switch, battery, wire, some string to move the arms, and something to offset the attachment point of the wires with respect to the axis of the motor (if there's still a gear attached to the shaft of the motor, you're all set). You probably already own everything you need for this one...

Sounds like a job for "muscle wire" :-)

BTW: A Servo(mechanism) operates on the principle of "feedback", that is, it is a complex way to control something, and possibly have it make it's own "corrections" in this manner.

Muscle wires, however.... provide a much simpler solution in my opinion.

Okay....can you explain "muscle wires" to me? Like I said, I'm a real novice at this stuff. But I love learning how to do stuff!

It's wires that shorten by about 4% when heated (usually electrically). They need tension to work efficiently. There's a tiny robot kit available called Stiquito - muscle wire pulls piano-wire legs forward, the springiness of the legs pulls the wire back to full length. Try googling for either muclewire or Stiquito.

The "Stiquito" sounds interesting. The ideas everyone is giving me is not only helping me with the current project, but my little brain has gone into overload thinking of future stuff I might do with my soft sculptures! Too cool! Thanks!

The "Muscle wires" link I provided should help.

Okay....thanks, I will check it out.

Muscle Wires® Now you can create fast, silent, all-electric motorless motion with just a single strand of our unique nickel-titanium alloy Muscle Wires. Muscle Wires actually shorten in length when electrically powered, and can lift thousands of times their own weight. Think of the possibilities for your next robotics or electronics project!

I looked at the spider: actually, not a bad idea! Will put it in my "idea pool". Thank you!

How small are you talking? The smaller it is the harder and more expensive it will be.

The "body" part minus the arms could be 10-12" (diameter) ; any bigger than that and it's starting to get a little too large. But I'm flexible there; I can make it to fit. If we're talking a big difference in price for the mechanics and I only have to make it a few inches bigger, than that can be done. And I am a novice at the mechanics of this, so simpler is MUCH better!