Robot arm joint - Powered planets
Planetary gearbox with a twist.
A robot joint driven by 6 DC geared motors.
Rather than drive the planets with a sun gear, The planets are motorized.
The 6 motors and planet gears are held in place by a cylinder which rotates freely inside the joint.
The outer ring and the sun gears form the connections for the rest of the arm.
This was one of those projects that you get in your head and at some point just have to do it.
More info and the Fusion360 / STL files can be found here https://makenweb.com/robot_joint