While there have been many frequent threads about wire management, one thing that we haven’t discussed is a neat wiring system that also allows for easy sensor and motor replacements. Some of the strategies of wire management are very neat, but replacing broken motors between matches would take years. Does anyone have any suggestions?
Yeah I completely agree. I’ve seen lots of really neatly wired robots but a lot of them are hell to interchange electronics on. This is why we made this:
It’s an electronics board, like the ones in FRC.
It’s a compromise between neat wiring and ease of use. The main thing we did here differently is that no wire belonging to any electronics on the board ever protrudes outside the board. For example, look at our motor controller wires. They’re bundled on top of their individual MCs, meaning the MC is not attached to the robot frame at all; just the board. We had 2 MC failures during our state championship, and both were identified and fixed within 3-5 minutes.
In addition, we also made 1 more board for the unlikely event that a very large amount of our electronics fail at once. We had the ability to just switch out everything pretty easily by removing a couple screws. This was a bit overkill and we didn’t end up using it, but because of the modular nature of the boards we are using it this year for our ITZ robot.
Interesting concept. Is it mounted on the plastic sheet that is part of your plastic sheet allowance? or to what is it mounted? Sometimes, students like to mount the motor controllers onto metal C-channel, etc. because it helps “sink” the heat generated by them. In fact, the motor controllers even have little nubs to make that easier, I think.
I didn’t even know they made that much heat
I didn’t know they had little nubs either…
Well I guess you learn something new every day
I am wondering this too. If it does not count toward the limit, it seems like a good summer project.
Yep, it’s a piece of very badly cut lexan. But honestly I don’t think sinking the heat matters too much, you’ll trip the PTC in your cortex and the heat sensors in the motors long before your MC fails.
I thought that Karthik said that there is no limit to how much you can use, only a limit to the types and the size of the sheet you cut it out of??
As for the broken motors, check this out: http://challenges.robotevents.com/challenge/58/entry/3921
AURA designed a block that offers easy removal of motors using 3D printed parts. You could replace a motor without having to struggle unscrewing the motor from a tight position. Could save a lot of time. However, this could be done only in Vex U. HS and MS could use a c-channel or something to imitate. Pretty interesting design; it won the bonus price in the Make It Real CAD Challenge.
I would be concerned with swapping out the whole board in light of <R1>:
<R1> Only one (1) robot will be allowed to compete per team in the VEX Robotics Competition.
Though it is expected that teams will make changes to their robot at the competition, a team is limited
to only one (1) robot. As such, a VEX robot, for the purposes of the VEX Robotics Competition, has
the following subsystems:
Subsystem 1: Mobile robotic base including wheels, tracks, legs, or any other mechanism that allows
the robot to navigate the majority of the flat playing field surface. For a stationary robot, the robotic
base without wheels would be considered Subsystem 1.
Subsystem 2: Power and control system that includes a VEX legal battery, a VEX control system,
and associated motors for the mobile robotic base.
Subsystem 3: Additional mechanisms (and associated motors) that allow manipulation of game
objects or navigation of field obstacles.
Given the above definitions, a minimum robot for use in any VEX Robotics Competition event
(including skills challenges) must consist of 1 and 2 above. Thus if you are swapping out an entire
subsystem of either item 1 or 2, you have now created a second robot and are no longer legal.
a. Teams may not compete with one robot, while a second is being modified or assembled.
b. Teams may not switch back and forth between multiple robots during a competition.
What? Where? There’s always been a limit.
Doesn’t that say swapping out an entire subsystem is illegal? I think I would only be swapping out part of one because subsystem 2 includes a battery and associated motors.
Agreed about motors, but batteries are associated with the subsystem’s power expander. I could see someone then could bring an entire subsystem 1, minus the wheels to a competition. Essentially having a replacement robot in a couple of subsystems with a piece missing here or there:)
Regardless - it would seem to me that you would want to bring the replacement board to inspection for software check.
Thanks for the suggestion, but I think you misunderstood what I meant about replacing motors. I meant that it would be hard to replace the wiring of the motor because you would need to cut several zipties, making the wires a disaster, and then have to plug the new motor in and try to keep everything neat. We try to always put motors in ways that are easy to replace. We sometimes use motor plates that just easily slide on and hold with a few standoffs or make sure that the screw holes are easily accessible.
Thanks. This is a great suggestion. I would love to try this if we ever have time where we aren’t frantically preparing for a competition.
As for the limit, I’m pretty sure I was just imagining that and made that up. Sorry for the confusion
Since Subsytem 2 includes the Cortex as well as the battery, I think if you were to have the second electronics board doesn’t have a Cortex and you just transfer the old cortex to the new board, no one would consider it to be “another” robot. That’s just my idea though.
Cortex would still have needed to be inspected for software…
Look, this is an interesting situation. My gut is this is a drop and play system, you might want to consider it an entire subsystem that should be inspected (cortex especially with the competition software compatibility for competition that should be tested as an important part of the robot)…
As I usually put it, “Ask Q&A” for a really answer.
At my event, if someone complains, I might suggest that common sense would see it as replacing an entire subsystem 2 without a Q&A to clarify.
As drive motors are considered part of subsystem 2, you’re probably ok if you don’t have a horrific drive breakdown and have to replace all your drive motors… Then again, if that happens, you probably have bigger issues than the legality of your electronics board.
As @lacsap said, probably best to ask a Q&A.
I do like the whole concept of putting the logic onto a modular structure you can swap out.
Can a three-wire extender connect a motor controller to a port, or does the motor controller have to directly connect to the port?
I will quote jpearman on this one: “Large voltage drops due to wire resistance and high current occur when the motor starts, this tends to cause any logic (ie. the MC29) to reset if it is placed at more than say 5 feet from the cortex. This is currently circumvented by keeping the MC29 close to the cortex and running 2 wire extensions to the motors.”
This is interesting, but we already have enough trouble fitting the lone cortex on our robot, let alone a large sheet of plastic.
I was kind of thinking the same thing and wondering if we were doing something wrong!