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Unread 06-03-2016, 22:21
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GeeTwo GeeTwo is offline
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AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
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Re: Legality of running a capacitor inline with roboRIO power

Quote:
Originally Posted by ImOn3618 View Post
As far as the brownouts go, all components go into brownout protection mode when actually driving. The roboRIO also loses connection.

When we set the robot up on blocks (minimal load), only the motors go into brownout protection mode.
Given the second sentence, I agree that a mechanical problem (chain alignment, grinding gears, etc.) is the most likely culprit. However, we had an issue very much like your first problem stated yesterday. That is, when we would hit an obstruction that largely stopped the wheels (moat was worst) or quickly reversed direction, the robot would lose connection. We spent a good bit of time brainstorming ways to prevent brownout (including the same capacitor you were considering) and strategies for the order we would attack the defenses. The thing is that if the issue seemed to be that the RoboRIO did NOT brown out, but go straight to blackout with no current spike in the logs. We finally tracked it down to a loose connection at the PDP inputs. The collision/sudden acceleration were giving us a voltage drop deep enough to reset the radio rather than just the motors. I don't recall if the RIO was resetting or just the radio. We changed to the correct bolts (long story there) and the problem did not recur over the next half hour or so of similar driving. OBTW, we found the issue just by wiggling and pulling on wires. A few queries revealed that the main power wires were secured by someone who did not know what LCKR (pronounced "locker") stands for. Loose Connections Kill Robots.
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