I have an article up at ECN on PID loops.
http://www.ecnmag.com/article-pid-loops-100509.aspx
Simon
PID Loops
PID Loops
Engineering is the art of making what you want from what you can get at a profit.
Re: PID Loops
I always thought that the D term sped things up, amplifying small changes, which is problematic in typical process environments with noisy pressure and level variables as things are pumped around. In my usual domain of mineral sands mining we only use PI and avoid D like the plague.MSimon wrote:Finally you have the D term. It is the rate of change of the error multiplied by a the constant Kd. The purpose of this term is to keep the system from changing too fast.
From "changing too fast" do you mean minimising overshoot? About the only use for D we have is temperature control, when it has a very large deadtime - and also since temperature is also a smooth/slow variable.
Herr Professor MSimon,
In order to aid the understanding of generally, but not specifically, knowledgeable individuals, please include a written out version of any acronym you use, as follows:
"I want to take a look at Proportional–Integral–Derivative (PID) control loops and how they are typically handled in software."
As a mechanical engineer, the version here is quite understandable. Yours left me racing for Wikipedia. Just a suggestion.
In order to aid the understanding of generally, but not specifically, knowledgeable individuals, please include a written out version of any acronym you use, as follows:
"I want to take a look at Proportional–Integral–Derivative (PID) control loops and how they are typically handled in software."
As a mechanical engineer, the version here is quite understandable. Yours left me racing for Wikipedia. Just a suggestion.