Let's Make Robots!

3DOF open hardware Arduino-based robot arm

I've been working on various robots for years now, building up my skills. I finally built my first successful robot arm. It's a 50cm reach version of the ABB 460. I'm looking for other robotics people to help me make more tools to go on the wrist. I've been toying with an automatic tool changer and there's already a wire for a single servo (claw?) and a 12v power source (suction pump?) In the video you can see a repeatability test. about 1mm. I drive too fast and it creates a lot of wobble. I haven't tested the maximum lifting force. I haven't mapped the total range of motion. ceilng appears to be ~30cm from the table. Reach is just over 54cm. Can turn >180 but the wires will be a challenge. Auto homing for calibration is working. Understands cartesian coordinates (inverse kinematics) and gcode. My next robot is going to be another arm with more degrees of freedom.

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I see you used stepper motors. Did you incorporate any means of position feedback or is it totally open-loop? The reproducibility looked great in video demo.

Open loop.  12-bit hall effect encoders were outside the budget.  I'm looking for people to collaborate with.  Any suggestions you have to improve the stiffness are welcome.  So are ideas for new tool heads or demos.

Here are some exploded diagrams of the assembly:  http://learn.marginallyclever.com/index.php/Arm3_v1

Nice work.  

I want to put something like that on my next bot and put the head (with android phone, thermal array sensor, ir lensor, two lasers, similar to superdroidbot but without arduino and servo in head) on the end of the arm so it will have more freedom to look up/down, change height of its view, etc.  Thinking of buying a lynxmotion arm but doubtful on whether it can carry the weight.  Some of the stuff sold by servocity looks interesting but pricey.

Great work.  Wish more people were building arms here.

Thanks.  This arm can carry 125g static load at full extension (50cm) and has a move ceiling of 30cm.  On my website you can find out more.

Very nicely done.  I see that you have used lauan plywood for construction.  What tools did you use for such clean and precise edges?

Is birch in the Lauan family?

I love laser cutters so much I bought my own.

The coloration of the photographs makes your wooden pieces look like Lauan Plywood, which is a wood from the Phillipines, somewhat reddish in hue.  It is often used in thin (small project) plywood and the veneer for hollow doors.

So, you cut them by laser? I suspected something of the sort, due to the blackened edges.  What sort of cutter do you have?  What did it cost, and will it cut thin sheet metal?

60W CO2 laser.  800x600mm.  Doesn't cut metal.

Can't wait to see how this one progrsses.

I would love to build something like this.