# Power Conducting Stepper Motor?

I have a question that I'm not really sure how to ask, so here goes:

So I know there's such a thing as a power conducting slip ring motor, which I assume allows the passthrough of power through the motor to power additional devices. I'm looking to see if there's such a thing as a power conducting stepper motor, or some way to hack such a thing into life.

My project requires the use of 3 motors in total - two stepper motors and one regular motor. I have to use the stepper motors (I think) because I require precise control over the angles for each, and the angles have to be able to traverse 360 degrees (not necessarily more than that, but having a little give in either direction would be good).

The motors will be connected in parallel, and are set up like the following:

(power source) ===> (motor 1) ===> (motor 2) ===> (motor 3)


The device itself will work very similar to this (animated GIF): http://giant.gfycat.com/ClearcutMajesticCirriped.gif

Where the first motor rotates over one axis and the second motor rotates perpendicularly. Each of those two motors require precise angular control, and again would need to go at least 360 degrees (as quickly and precisely as possible) but not necessarily more than that. Motor 3 does not, as in the gif it just spins relentlessly.

I'm new to motors.

Your understanding of slip rings seems correct.

There are many companies that make slip rings. So answering specifically to those is 'off-topic' for electronics.stackexchange. You might have to read through several pages of web-search results to find them.

Typically, slip ring costs increase rapidly the more separate contacts you need. So 4 power signals for one stepper motor, and two for the inner motor might be much more expensive than only two for power. It may also cheaper and easier to get a multi-circuit slip ring with two 'power' connections (for power and ground) and several 'data' connections.

Edit: One use for slip rings is connecting the buttons and airbag on a steering wheel to the rest of a car. So automotive slip rings are a mass-produced; they would be a low cost, relatively robust part. So you might find something to experiment with from a car 'junk yard'. It might be low-cost to get something there, and experiment with it, before trying to find 'exactly' what you need.

You might consider putting the control electronics 'on each motor', so that you only have to get power and ground through the slip rings. Then the electronics 'on the motor' would use that power to drive the motors power connections.

So the first/outer motor would be connected directly to its controller.
Power and ground would be fed through a 2 power-circuit slip ring.
The controller on the second/middle motor would take power and ground, and convert that into a signal to drive the motor.
Power and ground would be fed through a second 2 power-circuit slip ring. The controller on the third/inner motor would take power and ground, and convert that into a signal to drive the motor.

I assume the electronics on each motor would need to understand its position. That might be done using a gyroscope sensor on the motor controller, or use a low-cost radio.

I don't think slip rings are normally part of a motor - they are something that you have to mount to the motor or shaft. (Some motors may have internal slip rings to provide power to the armature, but those won't be used to pass power to the object the motor moves)

If your motor is only turning back and forth through 360 degrees, you may be able to use a flexible cable rather than slip rings.