[FVC]: Help - possessed robot!!!

[sovierr]

Our robot has started acting quite strange. Motors will reverse direction on their own, and sometimes the motors are running full speed even after the operator shows us that his hands are off the controls.

Has this happened to anyone before? Any suggestions? I am going to check for shorts (but it doesn't only happen with one single motor). Has anyone had any EMI problems with the motors and nearby PWM cables?

Thanks for any suggestions!

[EricRobodox]

We had a small problem like that, check the program. See if someone edited the program and put a loop or autonoumous. If not that, make sure nobody else has a similar crystal in the same room. But I feel it is most likely a programming error, maybe just it didn't compile correctly or there is code that needs editing. Try putting default code in first, to make sure its programming error rather than another defect, and then test. Then put in the new code. Hope this helps.

[fredliu168]

This actually happened to us during the Michigan Competition. It reached the point where it was so bad, that our entire robot shut down for 3 hours.

Heres what you can do. First try reloading the code, including the VEX master 2007 code. If that doesn't work, unplug all of your pwm cables, and try one by one to see which ones are functional (drivetrain, then arm) and which ones are not. From that, you can at least determine the problem.

If you still have a problem, you can email me at fredliu168@hotmail.com or PM me on CD. I'll try to help out as best as I can.

[nonother]

We've experienced this problem on our robot when the wires were not properly routed. Make sure not to run any wires parallel to each other, at least not close by. When you have wires cross, try to do so as close to perpendicular as possible. The shielding on the wires is very minimal, cross talk definetly occurs.

[macmaniac]

Yeah we (3053) were experiencing similar problems yesterday at practice. Me and my fellow driver spend around half an hour rerouting cables and the problem went away. But I'd advise check/reloading the code before you go ripping up cables. But I'm almost positive that one of/both of those methods will fix your problem.

[sovierr]

Thanks for all the responses!!!!!! Here is what I can gather after some diagnostics. The problem is unrelated to the program and the master code. It may still be due to pwm cables and EMI with each other. This is surprising based on all the bundled pwm's we use with our FRC bot, but these pwm's are carrying heavy current to run motors. The FRC pwm's are really used for sensors only.

The other thing the students have noticed is that it seems to happen only when the batteries get low. Perhaps there is an issue powering the receivers. I hope this may shed some light for those of you claiming similar problems.