03-19-2013 03:48 PM
I am needing help with PID tuning. I have followed the procedures, to the best of my knowledge, and can not get my PID to tune correctly. The system is a USB-6009, DART MAG-20 tach, and a DART 125DV56G motor speed controller. I am utilizing 0-5vdc input to the controller from DAQ's AO0. If I use a control slider in labview it works without oscillations. But I can not get the PID to stop oscillating. My VI will be attached. Any help and suggestions are greatly appreciated.
03-20-2013 12:31 PM
First off, I did not look at your vi because I do not have LabVIEW on my networked machine. But thanks for attaching it.
Now, PID tuning is something of a black art at times. If you have never tuned one you can go crazy at first. Check out this link http://en.wikipedia.org/wiki/PID_controller There is a lot of good info and a tuning section near the bottom which should help.
You say that you can't get the PID to stop oscillating, but how big is it? There will usually be a small amount even when tuned, it will look like a very slow sine wave. You also have to think about how fast you run the PID because that is how fast it can react to changes depending on tuning.