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Unread 08-02-2011, 10:10
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JesseK JesseK is offline
Expert Flybot Crasher
FRC #1885 (ILITE)
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Re: 9 motors too much?

4 Drive, 4 Manipulators, 1 Compressor (4 pneumatic cyllinders, 3 of which are 3/4" bore and less than 4"; the 4th is single-use for the minibot deployment)

We could easily use 2 less motors, yet they're added in order to balance the load under heavy usage during elims and after competition season. This typically only adds 2-4 amps of usage overall. We may swap the motors on our wrist joint for a dual-cyllinder pneumatic setup depending on driver desires in control.

By using some calculators out there, I've figured that if we're not pushing any other robots and no manipulators experience catastrophic failure, we will use 80 amps IF and only if we run absolutely everything at once. The current moves up by 25-ish amps if we're moving and turning. Of course, the chances that our elevator will run while we move at 13 fps is next to nill in the practicality of our strategy, so this is a worse-case scenario at best.

For fun (and to inspire someone to want to do batteries this year) I can estimate that a single match where we successfully put up 5 tubes on the top row and deploy a minibot will require 24 minutes of recharge time on a 6 amp charger. I think that this is a bigger indicator of whether or not a robot has too much current draw -- low batteries in elims lead to all sorts of incoherent behavior on the field. Again, it's an estimate, but it's useful to know how many chargers and spare batteries we need (and is good fodder for inspiration/training).
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Last edited by JesseK : 08-02-2011 at 10:20.