Quote:
Originally Posted by Luiz12
My P value by default is at 1. Should I leave it like this or start from .01. or should I start from 1 and then increase by .01.
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This may come off as a terrible answer, but do what works. Start with the default values, and observe how they make your system react. Then, modify the values accordingly.
Do you need the system to correct more? Raise Kp.
Do you need the system to correct faster? Raise Ki.
Do you need the system to slow down as it approaches the setpoint? Raise Kd.
Those are some overly general descriptions, but they work well in a pinch (and they also work oppositely).
It will be very hard to give specifics on PID constants without knowing about the system it will be acting on, because sometimes small changes can have huge impacts. That's why PID tuning takes such a long time - it's a lot of guess and check work until it works in a way you like.
In the meantime, I suggest to you do some reading on PID controller theory/tuning theory. Also, try and understand how the math behind them works in as much depth as possible (look through source code - I know you can look through the PID VI in LabVIEW). If you can understand how and why a PID controller works, it becomes that much easier to make one do your bidding.
Some other links to read when you have time (in no particular order. I like
this one because NI is awesome and does a great job with their tutorials and support).