PIDs out of control

[Ether]

Originally Posted by awallace3160

We are using 5-turn potentiometers and they are only intended to rotate 180 degrees maximum.

It's not clear what you mean. It could be interpreted at least 2 different ways:

1) The wheel is currently at 179 degrees and it is being commanded to go to -179 degrees. The controller will rotate the wheel 358 degrees counterclockwise to get to the commanded angle, because the controller does not want to exceed 180 degrees.

or

2) The wheel is currently at 179 degrees and it is being commanded to go to -179 degrees. The controller will rotate the wheel 2 degrees clockwise to get to the commanded angle, because that is less than 180 degrees movement.

Which of the above descriptions is what you intended? (or something else?)

We try to make sure that the pots are set to rotate near the middle of each ones range so as to avoid over rotating them if they go a little bit beyond the desired setpoint.

When you process the signal from the pot, do you let the signal go beyond 180 degrees? Or do you constrain it to be in the range +/-180 before using it? In other words, say the pot is at zero degrees, and then gets moved 181 degrees clockwise. Will your processed pot reading be +181 degrees or -179?

We are using the PotentiometerGetNormalized.vi to get our values

I don't know what that means, but it sounds like it is converting the pot reading to +/-180 degrees. If such is the case, depending on your code that could make the controller go nuts. I suggest you post your code for review.

So,I'm not sure if our program trying to reach this accuracy is hitting the pots' "blind spot" or not, because I'm not absolutely sure what that means.

If you've got a 5-turn pot and you are centering it and avoiding over-rotating, there should be no blind spot (a dead area where there's no usable signal).