Enough about gyro sensors and integrated motor encoders! Back to basics. Here I’ll pass along a few tips from our team about labeling your motors and wires that will make your life simpler in the long run, and hopefully avoid some headaches.
The first is our favorite: using the extra press-on license plate numbers that you get when you register your VEX team to label your robot’s motors.
If you’re anything like our team, you’ve probably been using blue tape on the motors, and then writing on said blue tape with…blue pen. Or in a better scenario…blue sharpie. As you can see in the above photo, there is absolutely no question about what motor number is connected to that wheel!
Our second tip is to label the heck out of your wires. We ended up dismantling our robot into its major components (forklift, star striker, chassis), at least 3 times over the course of this season to make various improvements and fixes. And every time we put things back together there was either a lot of testing required to make sure that we had each motor re-connected the right way or, alternately, turning it on and having it not work, and then doing a lot of testing to figure out which motors were plugged in the wrong way. Or not plugged in at all, sometimes.
In our very last round of taking-apart, my husband, who is an electrical engineer, recommended the following product: 3M ScotchCode Wire Marker Tape Dispenser, which he used in college. It’s got 10 individual rolls of tape (one for each digit, 0 through 9), with a metal toothey-ridge running horizontally across the whole thing (like on a box of saran wrap). Each roll of tape is just a continuous string of the given number: 4 4 4 4 4 4 4 4 (vertically along the tape). So you just peel off a little section, rip it off, wrap it around your wire, and you’re done.
I have to say that it’s kind of stupid-expensive for what it is ($37). HOWEVER, the stuff is made to stick to wires, and guess what? It actually sticks to the wires. We tried labeling our wires last year with blue tape “flags” or with label-maker tape, or numbers printed on paper and sandwiched within scotch tape. However, the blue tape was really big, and hard to read, and the other 2 options didn’t actually stick to the wires after a short while. As you can see from this photo, these labels are quite narrow, don’t really get in the way of other stuff, and as one who recently had to take one off of a wire, you basically have to cut them off — you can’t pull them off. That said, when you do cut them off, they don’t leave sticky residue behind. ‘Cuz guess what? They’re made for labeling wires.
So I guess if you’re going to fork over the $37 for your team, make sure that your kids understand that this is a valuable resource, not to be used for sticking on each other, or joking around with, etc. $37 for little rolls of stickers is…wow…but they are so useful that we chose to go for it, and be judicious.
One of the other coaches on the VEX World Coaches Facebook group (which you should join if you’re a coach or mentor reading this), mentioned that they use the flat-sheet version of these stickers, which can often be found at hardware stores (and is presumably cheaper without the dispenser).
Another coach offered another option that does readily stick to electrical wire… electrical tape! It has the benefit of coming in many colors, which allows you to have different colors for, say, chassis motors vs. manipulator motors vs. sensors vs. pneumatics. It does tend to be more bulky than the 3M product, but certainly a lot cheaper, and also available at your local hardware store.
Label the Whole Chain
Given the time we’ve wasted in the past, tracing wires & troubleshooting, we decided that we would label each segment of each wire. First, label at the cortex (shown above) so that if the wires get pulled out by accident (god forbid en masse), you don’t have to spend time re-inventing the wheel. Then we label each wire on both sides of the clip where the motor controller connects to the motor, and both sides of any extension wire junctures.
Extra Tip: At the Motor Controllers
Pretty much the second we unplug a motor from a motor controller, no one can remember if it had been plugged in with matching colors (red wire-to-red wire) or opposite colors (red-to-black). So we have a new labeling system for that too. When the motor-to-motor controller is connected with opposite colors, as you can see in the photo at right, we take a red sharpie and draw a slash on the wire label (on both sides of the label, on both sides of the clip), so that whoever is plugging things back in doesn’t need to think, worry, or ask about how it should be reassembled.
Find a System that Works for Your Team
I hope that this post has given you some good ideas for keeping your motors and wires organized on your robots for the upcoming game. Most importantly, I hope that it saves you and your team some time – it’s definitely more fun to build & drive robots than to debug wiring problems.
If you’re a coach or mentor reading this, I recommend that you establish some wiring/labeling protocols for your team; depending on their age & experience, your kids can of course participate in setting what those should be. Once you decide on a policy, one of the adult-level mentors may need to be the enforcer at the beginning to make sure that every robot group implements the standard consistently. Once the kids can see how much time it will save them in the long run by putting in a little extra effort to label everything, compliance will probably take care of itself. Universal labeling standards for a multi-robot program has the benefit of kids being able to jump in and help each other more readily.
Happy labeling! (And you thought you’d never have a use for all those press-on license plate numbers…)