This robot arm is (very) roughly styled as an 80% scaled version of the UR3 industrial robot. It uses the same design philosophy of simply placing a motor/reducer actuator unit at each joint, with six actuators stacked up to make a 6-axis arm. Now while the UR3 uses hollow torque motors coupled with harmonic drives ($$$) for the actuators, this robot uses the stepper motor/compound planetary actuators I posted here: https://www.printables.com/model/132262-robot-actuators. Two of the large actuators get used for the first two base joints, one of the medium sized actuators gets used for the elbow joint, and three of the small ones get used for the wrist joints. And the gripper* I've posted here: https://www.printables.com/model/132264-conformal-robot-gripper.

For the controller, I've used seven of Pololu's Tic T500 stepper controllers with custom firmware I wrote to support coordinated motion. You can find the gory details, including a Windows test utility program, here: https://drive.google.com/open?id=1rKRuWC4jAOekrds_WGUC7DkwlVsk2zdb

This is very much a work in progress and I'll be filling in the holes as I get time. In the meantime, please feel free to post questions in the comments section if you need details I haven't gotten to yet. Please read through all of the material here and ask me any questions you have before starting to build this - it isnot an easy weekend project!

And here is an excellent video posted by jlauer of his make of the arm: https://www.youtube.com/watch?v=tEbJV32GyYU

And another by jlauer with the development of his custom controller board: https://www.youtube.com/watch?v=RdmdFIhCo4M

*The gripper shown in the video is slightly different than the one posted.

For anyone interested in participating in the continued development of this robot, Thingiverse user jlauer has set up a discussion forum: https://forum.makerforums.info/c/ChiliPeppr/robot-arm

UPDATE: I've just posted an anti-backlash version of the small wrist actuator that has greater torque, less backlash and runs more smoothly: https://www.thingiverse.com/thing:3566678

Category: Engineering