How do you wire a rotating component?

[alleah2338]

So my team this year is using a shooter device and the design is for the shooter to rotate. Since this only our second year we have no idea how to wire the motor since it is attached to the shooter. We would like to do it without wires hanging everywhere. We have search how to slip mount them and haven't found anything. In past years books we have seen teams who have done something similar and can not figure out how.
Does anyone know how to do this?

[MrForbes]

Route the wires carefully.

We're facing the same problem, we made a pole that sticks up behind the turreted shooter, and the wires go forward from there to the top, center of the shooter. Haven't tested it much yet this way...but the wires did survive a couple weeks of testing when they were just hanging all over the place.

Our turret only moves 180 degrees or so. That might be different than yours.

Using slip ring contacts is a tricky business!

[Joe G.]

either using these: http://www.mercotac.com/html/430.html

or simply limiting the rotation of the device to 180 or 360 degrees, and letting the slack in the wire make up this distance.

Or, by putting the wires through the igus energy chain, and having the chain wrap itself around the turret as it rotates, while giving the chain space to expand to as it rotates the opposite way.

[alleah2338]

Thank you. I will try some of these ideas tomorrow. Our shooter only rotates 180 degrees. We have thought about tying them down with elastic so they can move but still be held tight. Has anyone tried that?

[EricH]

Originally Posted by alleah2338

Thank you. I will try some of these ideas tomorrow. Our shooter only rotates 180 degrees. We have thought about tying them down with elastic so they can move but still be held tight. Has anyone tried that?

What you can do in that case is: run the wires to the midpoint before tying them down. One of the ends will also do; the midpoint is just to reduce the length of wire you'll have to bundle and pull out of the way. Now, rotate the shooter to the maximum rotation in both directions, using a piece of string to simulate the wire. The most the string pulls out is how long you need your wire to be.

Having something to keep it out of the rotating components is good; try surgical tubing. It's easier to work with than elastic for this type of thing.

The one time my team needed to have wires move with something, it was a lift (with an arm on top, and the arm motors were on the arm), and we simply figured the max length we needed and made a pretty thick cable to run from the top of our base to the top of the lift and looped it into the robot so it hung freely.

[Al Skierkiewicz]

alleah,
Will I be seeing you this weekend? If so we can discuss this when I see your robot. As a general rule, if you can keep the wires near the center of rotation and leave a little slack, you will be able to turn without damaging the wires. If that is not possible, something like what Jim discussed above will work fairly well. Remember that latex is robot legal and easy to use as a springy tie point for a wiring bundle to keep it out of harms way.

The slip rings shown in the post above use mercury and as such have been ruled to be illegal on our robots. There are however, legal, brush type, slip rings that are available. McMaster had a few in previous years. They are pricey but fit under the single cost rule as I remember.

[lukevanoort]

Originally Posted by Al Skierkiewicz

The slip rings shown in the post above use mercury and as such have been ruled to be illegal on our robots.

That isn't quite right, they have been ruled legal in this year's competition: http://forums.usfirst.org/showthread...hlight=mercury. (I believe there were similar Q&As since at least '06, but I never really paid them much mind - my team always used the bundle as close to centre as possible approach)

[Al Skierkiewicz]

Sorry,
I hadn't seen that question. In the past, this coupling was considered hazardous as a robot collision could open the coupler and expose the mercury. The coupler has some very strict handling and mounting instructions that must be followed. I will make sure the Inspection team is made aware of the answer.