In most situations, range of motion is limited by the fact that we need to carry power or information past a joint. So, past a certain point there are either cables in the way, or the cables would stretch so much that they would either prevent further movement or break.

However, if we situate the conductors in concentric rings around or within the rotor shaft, we can have a joint that can rotate forever while keeping in contact with any modules on the other side.

What do we call this mechanism? Does it even have a name?

  • 1
    $\begingroup$ They are called slip rings, and they can damage your motor drivers. Very slight changes in impedance caused by the movement of the conductors (sliding around the ring) can cause the motor controller to over-compensate and blow capacitors. It took us a while to isolate the slip rings as our point of failure. $\endgroup$
    – Ian
    Commented Mar 4, 2014 at 16:27
  • $\begingroup$ Wow, that's really good to know! $\endgroup$
    – jzx
    Commented Mar 4, 2014 at 19:32

1 Answer 1


It's called a slip ring.


The Wikipedia page has several alternate names for it.

Be careful when using these devices, a cheap or damaged one with poor brushes will destroy a high-speed digital signal (and even worse, it will get damaged after you build a working prototype.)


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