In November 2017, we showed you [Chris Annin]’s open-source 6-DOF robot arm. Since then he’s been improving the arm and making it more accessible for anyone who doesn’t get to play with industrial robots all day at work. The biggest improvement is that AR2 had a closed-loop control system, and AR3 is open-loop. If something bumps the arm or it crashes, the bot will recover its previous position automatically. It also auto-calibrates itself using limit switches.

AR3 is designed to be milled from aluminium or entirely 3D printed. The motors and encoders are controlled with a Teensy 3.5, while an Arduino Mega handles I/O, the grippers, and the servos. In the demo video after the break, [Chris] shows off AR3’s impressive control after a brief robotic ballet in which two AR3s move in hypnotizing unison.

[Chris] set up a site with the code, his control software, and all the STL files. He also has tutorial videos for programming and calibrating, and wrote an extremely detailed assembly manual. Between the site and the community already in place from AR2, anyone with enough time, money and determination could probably build one. Check out [Chris]’ playlist of AR2 builds — people are using them for photography, welding, and serving ice cream. Did you build an AR2? The good news is that AR3 is completely backward-compatible.

The AR3’s grippers work well, as you’ll see in the video. If you need a softer touch, try emulating an octopus tentacle.

Thanks for the tip, [Andrew]!