2020 Motors and Controllers FRC Blog should have been posted in May

What criteria does FIRST use to determine the legality of a motor?

I don’t know about the motors themselves, but motor controllers are tested very thoroughly to ensure that they properly obey the enable/disable signal.

Then wouldn’t it be possible for CTRE/Vex/REV to do some of the enable/disable testing?

Well, I’m sure they do plenty before they submit the hardware and firmware to FIRST. But on general principle, you don’t want safety V&V to be done by the same people that wrote the software…


Yeah, I wouldn’t compete in a match without a working estop button.

Even if the manufacturer collects the data, FIRST still has to review it, thoroughly. This relates back to my post above. There is probably a lot more testing required for the motor controllers than for the motors.

That, I’m not sure if anybody knows.

There are some things that you can reasonably assume, however…

  1. 12VDC. Unless the robot power source changes, 12VDC is the motor’s input power. (You might see the odd 18V motor in there–there has been in the past–but they can’t run on that 18V.)
  2. Ability of the manufacturer/supplier to provide some large quantity of motors. This is actually one of the reasons that a very old but beloved motor–the Globe motor–was removed from competition use a bit over a decade ago. They’ve cropped up in illegal locations for years since then…
  3. They may look at power draw, total power on the robot, and other stuff–back when I was a student, the motor quantities were limited pretty much across the board–but I don’t know how much of that they look at.
  4. If they aren’t looking at safety and “high-school-student-resistance” factors, I got some words for whoever isn’t doing that, and they ain’t complimentary.

Overall, though… we just don’t know for sure.

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Given that the Falcon stalls at 257 A, I have to assume that’s not a criterion…

Used to be a rule note about “to keep the power available for the robot at the same level”…

That went out the window at about the time they removed all the quantity restrictions for some reason.

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