PID without the D

Alex.Norton · #1 22-01-2008, 16:37

I would think that doing a PI would be really unstable. The D part has the effect usually of dampening the I since the I will always overshoot the goal. Of course the instability will dampen itself over time because of friction in the system but I would agree that I have never seen a PI loop. Plenty of P+D and P-D and just P loops but never a PI loop.

What exactly is your reason for not using the derivative part of the loop?

billbo911 · #2 22-01-2008, 16:57

Quote:

Originally Posted by Alex.Norton

Plenty of P+D and P-D and ......

Not meaning to side track here, but that is what I'm going to do.

P+D and P-D, which is correct? Or should I ask, how do I determine which to use?

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