unknown electrical issue

[BriteBacon]

Originally Posted by 3175student17

This is very strange, and I don't know the cause other than low battery, but something I know is that we would have the same problem from time to time, and I'm pretty sure the robot is enabling and disabling at the same time while this happens, as whenever this would occur in a match, our pneumatics would retract and extend with the twitches, if they were extended beforehand. Also, our LEDs would flicker greatly, which were directly wired to the PD board at 20 amps. I don't know if this would help, but just contributing if possible.

The same thing happened to us at Gull Lake in semi's, the only way we figured out to fix it and prevent it from happening is by restarting the driver station after each match.

[Greg McKaskle]

A cRIO crash due to low voltage or otherwise should not brick the cRIO. Every time you open the Anderson switch to "turn off" the robot, you are removing power from the cRIO. It isn't aware you were going to do that, and it runs out of juice and has an abnormal shutdown -- a crash.

When voltage drops below a threshold, the cRIO disables outputs. In its status packet back to the DS, it explains that it cannot run outputs because it is disabled. This is similar to what happens with a watchdog timer. The DS it telling the robot it can be enabled. The robot is saying it chose not to be. I don't believe rebooting the DS has any effect on this. I don't believe it hurts anything, but I don't believe that it fixes issues with a low voltage battery in anyway.

Please post the logs and that will give some data to confirm our speculations. Or it will hopefully point in another direction.

Greg McKaskle

[audietron]

I will post logs ether tonight or tomorrow morning due to the fact i don't have the robot or driver's station at the moment. I am mostly thinking it is a short like many people have said. I will check to see what gets really warm when we run it today and see if it is in fact the power cables for the DSC.
The battery leads do get somewhat warm as well as all 4 Drive cims, The main breaker does not get hot as well, this is why i am pretty confident is just a short somewhere.
Thanks for all the help.

[ryaneogilvie]

We run a 8 motor drivetrain (6cim 2minicim) and this happens whenever our battery is low (Which can easily happen after 3min hard defense). I don't believe it is any problem with your robot or wiring, instead the battery at low levels is simply unable to provide enough current for 4 cims to run at full from stop, especially when turning and running a compressor. When you attempt to draw to much current from a low battery, the voltage can drop so low that your robot stops running commands. (I believe the minimum is around 5 volts). The constant starting and stopping is due to the motors drawing to much current, losing control because of low voltage, stopping, regaining control, then repeating. If you just try slowly accelerating you should be fine, but you should just change battery.
watch the driver station - if your ever dropping below 5 volts you're probably at low battery. (or you're stalling motors, inefficient drive base, etc...)
It's unlikely because you mentioned it happening after 3min of hard defense, but this can also happen because of communication interference when to many wifi networks are present. You'll see the robot enable and disable erratically on the driver station. In this case one fix is to switch to 5ghz wifi.
hope this helps.