PID coefficient

[Pierrot]

Hi,
I use a PID loop but I don't know which values I must give to my coefficients.
Please help me...

[Paolino]

The first questin is: which kind of system are you going to control with PID regulator?

A lot of books and articles have been written regarding this automation question. If you know anything or very few on this argument I suggest you to read careffully ZIGGLER & NICHOLS theory which is interesting. They have a euristhic approach to the PID tuning operation and their method gives PID coefficient that maintain the controlled system stable. I bought and have used, in the past, industrial digital thermoregulator made with a "modified Z&N method" and they worked well.

In general, there are a lot of approaches; if you do not know the state equation of your system you could also think to estimate them with ARX or ARMAX methods.

I think that your question opens a large field full of answers. Take a look at the theories I talked before and then choose a method that can be the best for your controlled system.

Paolo

[Pierrot]

In fact,like you told me, I don't know the state equation of my system. So I will try to find some documentation about ARX or ARMAX methods.
Thanks