The potential performance of a control loop is limited by
the apparent or real dead time in the loop. You are up
against a stone wall if you try to get better performance
out of a loop, than the dead time will allow, by tuning
alone. If you need better performance, reduce the dead
time, reduce the disturbance, use feed forward or do
something else, but tuning can do only so much. There are
sophisticated approaches to reducing the problem, but
these are not for the novice.
For more information you may refer to a booklet "Controller
Tuning and Control Loop Performance, a Primer, Second Edition"
which is available in the US at the cash discounted price of $17
if paid with a check or money order.
If you want more information on this booklet, visit
me for a four-page brochure. It has sold 29,831 copies to date.
Companion software ($11) is available and a link to that page is provided.
David W. St. Clair
Straight-Line Control Co.
18 years ago