Easy, cheap, reliable, useful robotic fingers.

latigerlilly

Hi,

I was wondering how to make easy, cheap, reliable robotic fingers? I would like to make a facsimile of human fingers.

I was inspired by this:
www.sciencetoymaker.org/robotFinger/assembl.html

However, I would like to use more durable material than tape and cardboard (but almost as cheap). I am a relative newbie (this is only by 3rd BOE project) so easy would be appreciated, too. Is there a better design than this? If so what?

Any suggestions?

Thanks and much appreciation,
Lilly.

fmx95

Have you heard about Flexinol muscle wires? If used with a stronger (metal/plastic) version of that hand with the strings replaced with lengths of this wire you may be able to build a hand strong enough to lift light things. I have never used these so i don't know their power, but i'm sure someone else here does..?

Flexinol Muscle Wires @ Jameco

This might also be useful.

Flex Sensor @ Jameco

Or, you could use two servos on a setup like you linked. One to pull the four fingers and one to pull the thumb. ( Springs would be used to re-open the hand. )

If this will only be used to lift objects consider using less fingers. It would be less 'cool' but much more practical.

This probably didn't help much, but i just thought i would add my 2 cents.

,Travis

latigerlilly

Hi Guys,

Yes, I considered muscle wires, but as I understand it (correct me if I'm wrong), the wires change length/shape when heated. It is the resistance in those wires that heats them and changes their shape. Then, as it cools, they bend back. I'm afraid that in an enclosed area (a realistic hand), the wires won't have enough ventilation to cool back down. Also, it might present a fire hazard. If this is not true or if there's an engineering workaround to these problems, then I actually prefer the muscle wires. They have some that can lift 2 kg (4.2 lbs). That's pretty impressive.

Thanks,
Lilly.

PAR

latigerlilly said...
I was wondering how to make easy, cheap, reliable robotic fingers? I would like to make a facsimile of human fingers.

I was inspired by this:
www.sciencetoymaker.org/robotFinger/assembl.html

However, I would like to use more durable material than tape and cardboard (but almost as cheap). I am a relative newbie (this is only by 3rd BOE project) so easy would be appreciated, too. Is there a better design than this? If so what?

Any suggestions?

"facsimile of human fingers" ?· That implies a huge undertaking, given all that a "finger" is.
Do you want tactile, heat, pressure, movement in 2/3 dimensions, fingerprints, sensing at a (short) distance, strength, ....?

"better design" (than the "inspirational" one)? What do you want your finger(s) to do?

"easy, cheap, reliable" ?· Again, to do what tasks? How cheap, how easy, how reliable?

The answers to these preliminary questions will start to define your problem / task, and guide how you approach the solution.

For example, you suggest that the tape/cardboard model is not durable enough material. Why isn't it durable enough? What function(s) do you want your finger(s) to do that will require more durable materials? Knowing the answer to that question may suggest the kinds of materials and construction that will be needed for your finger to perform to your requirements.

PAR

allanlane5

Usually, of "Easy, Cheap, Reliable" you have to pick 2 of the three. You can't get all three.

And the link you gave shows an illustration of how tendons work -- I don't think it would make a reliable robotic hand.

I've made Mindstorms robots with grippers -- and even a simple gripper tended to be the most mechanically complex part of the robot.

This is why most grippers for robots I've seen tend to be servo based (cheap and easy) or motor based with intricate gearing (reliable, but not cheap or easy).

Zoot

Wasn't AIman working on a hand using PVC tubing for the fingers and cables (tendons) hooked up to servos?

Yeah, here it is. Don't know what the status is of his work: http://forums.parallax.com/showthread.php?p=609032

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