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Open Source Robotic Arm

by oomlout, published

Open Source Robotic Arm by oomlout Mar 23, 2009

Description

Perhaps one of the funnest projects we have attempted around the .:oomlout:. offices. A five degrees of freedom robotic arm. While we have spent many hours twisting knobs to move pop cans from one point on our desk to another sadly it has not progressed much further.
The main reason for this is the sum total of math knowledge around the oomlout.com offices is about 4 (don't ask us to show our work on how we calculated this) so inverse kinematics is well beyond our reach.

We are releasing it in an imperfect form in the hope that the clever Thingiverse denizens will be able to make it better.

Why this isn't quite ready for sale:
-We lack any inverse kinematics program which makes moving the arm intelligently nearly impossible.
-Without software limits on the servos it is capable of stripping the low cost hobby servo motors (this is alright for testing as they are only five dollars) (we have stripped two in the life of our arm and both happened when we were asking it to do silly things) (this can be fixed by upgrading the servos)
-We haven't completed the 3d model or assembly instructions just yet, but by studying the photos it is possible to assemble. (think more jigsaw puzzle than lego set)
-The gripper, lets just say the gripper needs a little work.

That said it is an amazingly fun toy to play around with, and a good starting point if anyone has ever had a desire to make the perfect robotic arm (it is open source so you'd be free to make and sell your own)

(shameless plug)

For more details about becoming a Robotic Arm Developer visit our blog
(http://www.oomlout.com/blog)

Recent Comments

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Hi i4lingual;

Lovely to hear that you've made one and hope it's working well.

We used acorn nuts as the 'rollers' to support the base.
Hi, thanks for the interesting project. I just finished assembling my arm, however, I haven't been able to make out what you are using as rollers to help support the base. I see in the photo you have something there but it isn't mentioned in the instruction. Thanks again.
Whoops, I mean "Sensable".  Here's a video of it in use for 3D sculpting:  

youtube.com/watch?v=REA97hRX0WQ

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If you print this Thing and display it in public proudly give attribution by printing and displaying this tag. Print Thing Tag

Instructions

Cut the pieces out of any 3mm (1/8") sheet stock. (the file is also available for free at
Ponoko (http://www.ponoko.com/showroom/ClementFletchersPlace/open-source-robotic-arm-2674)) (ie. just pay their cutting cost and shipping)

Assemble using 3mm hardware
(required pieces 3mm x 10mm screw, 3mm x 15mm screw, 3mm x 30mm screw, 3mm washers,
3mm nuts, 3mm lock nuts)
(all available from McMaster Carr, buying a hundred of each is a good idea)

six hobby servos (we use these tinyurl.com/c2ygay these ones would be better tinyurl.com/cwzygn and if you're looking for more precise motion we would recommend more expensive similarly spec'd servos)

pololu 8x servo controller tinyurl.com/c2ahys (you can drive all the servos from an Arduino using the softwareServo library, but the added precision and ability to set speed restrictions on this unit is very helpful, it also greatly simplifies the wiring).

Any questions or suggestions we'd love to hear them or try and help you out [email protected]

(have fun conquering the world)
Hi, thanks for the interesting project. I just finished assembling my arm, however, I haven't been able to make out what you are using as rollers to help support the base. I see in the photo you have something there but it isn't mentioned in the instruction. Thanks again.
Hi i4lingual;

Lovely to hear that you've made one and hope it's working well.

We used acorn nuts as the 'rollers' to support the base.
Could this be used as a haptic device like Sensible's "Phantom" products?  http://www.sensable.com/industries-application-development.htm
Whoops, I mean "Sensable".  Here's a video of it in use for 3D sculpting:  

youtube.com/watch?v=REA97hRX0WQ
Do the servos that you recommended (the ones in the links you gave) come with the hardware to mount the servo arms to the acrylic? if not where can I get it 
hi ofcourse i'll give it a try, where i can find like a tutorial or an ensamble guide...?? in the diagram are A LOT of pieces!! XD

thanks in advance
For inverse kinematic you might be interested in OpenRAVE, a GPLed robot simulation engine:

openrave.programmingvision.com/index.php?title=Main_Page
Regarding the gripper, the original Tomy (later Radio Shack) Armatron used a simple and effective gripper, and any number of Lego parts would also work well, IMHO.
Не плохо) Максимум сколько такой робот может поднять веса?
Your project is fantastic. But i think there would be a way of putting almost all servos in the base and using straps and pulleys like in some real robotic arms. This would make the arm much lighter. If I give it a try, i swear i'll share it with you.
any issue with using 1/4" or .22 thick acrylic or polycarb?
it may be too heavy, but then again i have no idea. give it a shot and let us know how it goes!
No need to sweat the math, ooom, that's already in the can. Hike over to EMC2, aka LinuxCNC.org, for the open-source Enhanced Machine Controller. I'm just a lurker and noob over there, but they have kinematics totally covered. See "EMC2 5 axis" on YouTube.
Very very nice! thanks!

I ordered via Poulou
oomlout, we miss you already!!! convince your girl to move to NYC next =)
marv - in reply to Guest
Did you ever thought about using the Wii Remote with Infrared Lights Mounted to the Arm Joints? Instead of touch etc. sensors.
Hey zach, can this be used for reprap???
possibly. our extruder is pretty heavy and the robot arm probably doesn't have the precision we need.

that said, i'd LOVE to see a reprap that consists of a robot arm holding an extruder.
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