Help- Motors running when they shouldn't be

[apm4242]

Hi

We are having an issue with one of the motors moving very slowly in both teleop and autonomous. At first I thought it was because we're using an Xbox controller and we would just have to code a deadband in Labview to prevent this but then we saw that it was also happening during autonomous, which I can't explain. It's even happening during autonomous routines that don't include that particular motor...

Does anyone know why this would happen?

Thanks in advance!

[Mark McLeod]

Possibly a mis-calibrated motor controller.

You can also introduce a problem when you calibrate to a really sloppy centering stick that might work fine in teleop, but autonomous which doesn't use the sloppy values has a different center.
So pure neutral isn't neutral anymore.

[GeeTwo]

Concur with Mark on controller calibration being the most likely issue.

It could also be a faulty connection on the PWM line that intermittently gives pulses in the drive speed range; less likely.

Also, check to see if the controller tries to run the motor when the PWM is disconnected. That would be sign of a problem inside the controller.

Another thing you can try is to switch the left and right PWM wires at the RIO end and see if the problem follows the port or the wire/controller/motor system. If it switches, you have some sort of problem in software or the RIO. If it stays with the same motor, it's somewhere on the hardware side of that connection.

[laplacier]

Have you tried loading a new, unmodified RoboRIO project to the RoboRIO? If that makes the issue go away then the culprit could be your project.

I had a similar issue occur to another team, but that was a more sinister issue which I hope is not what is afflicting you. However, I don't think anyone would be capable of replicating this.

During build season when one of the neighboring schools stopped by our school for assistance they complained that their motors would run nonstop as soon as the robot was turned on. That didn't make much sense to me since code on a robot would take a little bit of time to boot up when powered on. They set up a time to bring their robot over to us to take a look. Turns out they had wired several components wrong to the power distribution board, including the RoboRIO. The RoboRIO was fried in such a way that it was sending junk data down every signal port including ethernet. The total damage was a RoboRIO and three Talon SRs (and the routers survived being plugged in reverse for an extended period of time!). Lesson learned: check the wiring manual before plugging in your sensitive components willy nilly!

[apm4242]

Thanks for all the replies! I'll calibrate the Talon SRX and then move on to the other troubleshoots. The robot is currently bagged but I'll follow up with a post after I can make the changes.

[apm4242]

We got it fixed. First we calibrated the talon srx but it didn't seem to help. Then we added a 0.2 deadband in the code - very little change. Finally we calibrated the talon srx again just in case and it worked. On the second calibration, we made sure to leave the stick centered for a good 5 seconds before releasing the CAL button.

Thanks for the help!