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Unread 15-03-2015, 23:23
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jman4747 jman4747 is offline
Just building robots
AKA: Josh
FRC #4080 (Team Reboot)
Team Role: CAD
 
Join Date: Apr 2013
Rookie Year: 2011
Location: Atlanta GA
Posts: 418
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Re: Safety Issue: Robots Moving in Pits

Quote:
Originally Posted by SJaladi View Post
I think it's not so much a matter of not being able to make a simple platform, but rather it being much more time efficient to simply pull out the breakers. I agree that it would be highly unfortunate if one were to plug the breakers back into the wrong spot, but this can be easily manafged by a bit of attentiveness and clear labeling of the ports on the PD board.
My only problem with that is that the safety system is susceptible to fail due to the same kind of mistake that would cause the problem it is there to prevent.

Programming & e-stop scenario: Team 9999 has just arrived to their regional on Saturday morning and is eager to test their auto which closes a gripper around a can and drives backwards with it. They orient the front of the robot facing the inside of the pit with can in place. The operator places the laptop on a chair behind the robot which is facing the isles. In the software there is a front panel button (Boolean labeled "Disable Drive?") that disables the output from the state machine to the robot drive vi. Unfortunately the programmer got the wires mixed such that when "Disable Drive?" is true the output from said state machine is sent to the drive vi instead of zero. Thus when the robot is enabled and successfully grabs a can the operator raising both hands in triumphant celebration just misses his laptop as the robot proceeds to back away with it and the can.

Breaker scenario: Simultaneously one pit over, team 9998 had a rough day yesterday. An old victor 888 gave out and they hastily replaced it with a gifted Tallon SR. They quickly prepare to power up the robot and upload code that initializes a Tallon instead of a Victor. A rookie student is ordered to pull out the breakers for the drive motors only and returns with 4 40 amp snap actions in his hand. With a glance at the PDB his Sr student is satisfied and orders the robot on. The robot then proceeds to take a nice long arc out of the pit directly into team 9999's runaway bot. What they hadn't realized is that yesterday they managed to hook up the Tallon's Motor +/- side into the PDB. Furthermore the rookie had removed two breakers for drive motors and two for the lift and not the one on the revered Tallon.

TLDR? yes. Unlikely to happen next to each other? Yes. Completely improbable on their own? Not even.
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