Quote:
Originally Posted by EricH
I wouldn't quite say that the ARA allowance last year was quite without performance characteristics. For one thing, van door and seat motors have been in the KOP before, and the van door motors were available from AM (which does provide the spec sheets); for another, if you need to look up the characteristics and you have a motor part number, that's pretty trivial with an internet connection.
I'm thinking that squirrel is right on not putting R/C components on FIRST robots due to the loadings. If you're stalling a R/C motor, you're doing something very wrong. At least, that's the aviation side of the theory--I don't know about the ground vehicle side. How often do FRC motors stall or come close, especially in a pushing match or a robot autonomously running into the wall?
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I wanted to expand on these two paragraphs, real quick.
First, on ARA motors. I inspected at two regionals, and didn't see a single ARA motor. Even though it gives teams a wide variety of choice, is readily accessible, and was completely legal, a vast majority of teams decided to stick with what they knew. Using a motor in the KoP has two advantages: you know it's characteristics, and you can test it since you have one sitting right in front of you. With the ARA, you go to the junkyard, get a motor, then have to take it back and see if it'll do what you want. Those extra steps and unknowns make it not worthwhile for most teams during a time-constrained build season. It'll be interesting to see how many teams used their voucher to get motors in the off season, tested them and understood them, then decide to use them this upcoming year.
Next, on stalling. I don't think there's a single motor my team has ever used that hasn't been stalled. CIMs stall all the time in pushing matches. We've stalled (and burned out) FP and BaneBots motors. We destroyed quite a few Tetrix motors. We stalled the window motors during prototyping on our BreakAway robot, before we figured out our final design. We briefly stalled the AndyMark gear motor this last year almost every time we used it. With RC cars, you're more likely to suffer wheel slip than stalling - the cars are so light and the motors spin so fast, even driving it straight into a wall will just result in the wheels spinning while you go nowhere.
Finally, one more thing to consider: The more options you add, the harder inspection gets for everyone. If you add a speed controller that can only be used with 20A breakers, then inspectors need to check that. If you open it up completely and allow any speed controller that meets certain requirements for current, voltage, thermal shutdown, etc, then the team would need to bring documentation for that speed controller, and the inspector would need to be able to understand that documentation. This is something teams are notoriously bad at doing (I've encountered a lot of situations where a team uses a pneumatic part that we need to verify the operating characteristics of, and they don't have a spec sheet with them. With no internet at the venues, getting one can be difficult!). The last thing we need to do is introduce additional inspection headaches!