We have been having problems with the microcontroller reverting back to autonomous mode during the middle of the match. It has been occurring more often than not.
In the first event we went to we only had one battery and we were told that a low battery charge could cause this. In the second event we went to we brought 3 batteries with us to make sure we always had a fresh one (but the problem persisted).
We switched transmitters and the problem went away for two matches but then came back in the quarter and semi-final rounds. I heard from at least 6 other teams that they had similar problems. Also during two rounds our robot and out alliance partners robot had this problem simultaneously.
What could be the cause of this problem as it results in a 20 second down-time during a match?
There are a few possible causes of a Microcontroller reverting into autonomous during a match. The only reason that the Microcontroller reverts to autonomous is when the Microcontroller experiences a resets. The causes of this reset are most commonly low battery voltage and/or intermittent battery connection caused by damaged or loose electrical contacts. A rare cause of resets are static discharges in a low humidity environment which may occur when the statically charged robot comes into contact with a metal object on the field. This metal-to-metal contact can be minimized by using VEX foam as bumpers (P/N: VEX-FOAM-60).
The battery issue (low voltage) should be resolved by our purchase of two additional batteries so we always have a fresh charge. A loose connection of the battery to the microcontroller is something that we’ll look at.
The restarts have happened in the middle of the field with no contact to the edge of the field or with another robot.
Bigger question, why can’t this behavior be replicated outside the competition field? Try as we might, it just doesn’t happen.
**As we stated before, the only known way for a VEX Microcontroller to execute the Autonomous routine during a match is when a reset happens.
It is possible that a “good” battery was not fully engaged during the match when the issue occurred. You can not repeat the issue because the good battery is now always fully engaged.
One thing to look at is the very tip of the pins on the battery. There are 3 folds of metal that come together to make the tip of the battery. Sometimes one of the 3 sections of metal gets bent up, preventing the battery from being fully seated into the VEX Microcontroller. This can cause an intermittent power connection and thus a reset. **