Wiring the turret

Does anyone know how to wire a rotating turret? We were thinking of a spring loaded reel that could pay out or retract wire so we don’t have 3ft of slack hanging off of our motors. Does anybody have any ideas?

Thanks, Team 612

How far does your turret rotate and why? It will help figure out how to run wires.

This. Part of the reason we’re sacrificing complete turret rotation on our robot is simply for ease of wiring it.

It will rotate a maximum of 270 degrees.

How about:

Our elevator system is in the middle of the of the circle. If we were to do that:

Originally Posted by DonRotolo View Post
Slip rings are to be avoided where possible.

Run your wires via the center of the rotating circle. Just leave considerable slack so the wires don’t twist excessively, and limit how many times you can turn the circle before having to turn the other way. 360 degrees either direction is not at all difficult.

Then our balls would hit the wiring

Yes. Avoid the heck out of slip rings. They’re expensive and require more engineering time than they’re worth.

This would be difficult to do if balls are going through the center of the turret. Have you considered pre-coiled wire? If you anchor it to take the stress of the motor leads, it would stretch during rotation and relax during counter rotation.

Hmm, in that case, maybe you should ask a team alumni from 2006.

Alway make sure there is some kind of mechanical stop that limits the turret from rotating further than the wires can go without hurting the motors or other systems. So if you go 270deg stop the turret from going 271+deg. It can be a rope, cable, or some bolts that hit some part of the turret. Anything to keep from stress on the wires to the motors or sensors.

That year we had a hopper behind that elevator system and we could wire directly to it via the hopper we ran wires straight up the side of it. This year the tallest point of our robot is the turret so the wires have to go up to the turret, not wired next to the turret.

What options do we have if our turret rotates all the way around, 360 degrees (no limits)?

Attach all the wires on the turret to a common point on the turret, and run them all together from there (you can use zip ties, wire mesh, split tubing, or other ways to do this). From that single point, you’ll have an attachment point that closely matches it when the turret it halfway through its rotation. At this halfway point, you’ll have the most loose wire to deal with - rotating either direction from there will pull the wire and decrease/eliminate looseness as you get to the two extremes.

Once at that point, the easiest way I can think of to manage the wire is to have it spring loaded in some fashion. This could be as simple as a rubber band that helps provide a little tension - however you want to make sure you aren’t stressing the wire (having some well mounted cable running along with your wire can help with this - the stress will be on the cable, and the cable will help direct the wire).

Regardless of the design you come up with, make sure the wire moves through a “safe” zone the entire time - and area with no sharp edges, and nothing but smooth curves. The last thing you want is for a sharp edge on the turret to cut through your wire!

Another possible solution: run a post that goes up and over your turret (probably behind the turret in the area it can’t rotate to face). You can run the wires along there, then drop them straight down onto the turret. That should allow maximum rotation with minimal loose wiring.

Thanks we will try it out!

We are doing something very similar. We too have a rotating turret with the balls running up the middle, so we can’t run the wire there. We are putting all our wires in mesh tubing type thing (sort of like a finger trap), and running them together to a single point on the turret. To deal with the loose wire, we are using a tool balancer from McMaster to pull the loop of wire down.

We did look into slip rings, and they were extremely expensive. I’m not sure there’s a huge benefit to having unlimited rotations anyway. As long as you have 370+ degrees of rotation, you will be able to aim in any direction. Simply “untwist” as needed.

What options do we have if our turret rotates all the way around, 360 degrees (no limits)?

The only thing I could think of is to use insulate some rings on one side of your turret that you tie your motor leads to, and use some brushes or something on the other side to complete the circuit. This may or may not be legal, but is how it is done commercially many times.


Hope that helps.

The power chain from Igus that came in the KOP might be a viable option for you.

We looked at the Igus power chain yesterday. When fully deployed, it became an appendage, sticking out beyond the robot! Oh well. . .back to the drawing board.

Dr. Bob

Chairman’s Award is not about building the robot. Every team builds a robot.

With a little work, the igus chain can be made to flex both ways. After that, you can use a bungie or surgical tubing to keep it snug against the robot. 3539 did that last year when we designed our arm that went to either side of the robot.

If slip rings are not viable, try bringing your wire in from directly over top of your turret. We did that in 2009 (we had a small crane extending right over the turret and dropped our wires straight down). The slack in the wires gave us 360 degrees of turn.

Put mechanical stops so the turret can only move about 45 degrees… after all, that’s all it needs to move, right?

Then you can just attach the wires on a mast, and route them to the moving part of the turret.