Floating planets robot joint - Apr 15, 2019

This was one of those projects that you get in your head and at some point just have to do it.

It is a little on the heavy side (147 grams) but the advantages are

TODO: Add encoder for servo control.
The idea was to drive all 6 motors in the same direction for torque but when approaching the set-point reverse a few motors and provide backdriving to prevent over correction.
You can drive 3 forward and 3 backwards to hold position.

Motor: ebay 3v 30RPM gear motor   You will need 6 of these.

CAD view (both sides are the same)

Not my best CAD work but as a prototype it worked so much better than expected.

See it in action

It is quite powerful but i forced it by hand too many times and striped the planets. The planets will need to be better than PLA to be useful.

Some construction photos

Additional materials used


parts.zip  STL parts ready to 3D print
fusion_360.zip  Fusion 360 design files

I hope someone finds this useful

Thats all folks