PID controllers applied to MIMO processes


Thread Starter

Zachariah Taheri

I want any PAPERS about Multivariable PID controllers, or PART/CHAPTER of a BOOK about this topic. would you help me please?

H. Eder, ACT

Can you describe the problem you are trying to attack. For 2x2 systems PID control can and has been applied - but is very cumbersome to tune
and thus not recommended. Model Based Control is much easier. For larger and non-square systems there is no way around MBC.

A very simple MBC algo can be found at "" under "Tecnology"
I won't argue that it is always easier, but MIMO problems have been solved for years with PID-based approaches, even non-square ones. Feed forward, ratio, cascade, split range or parallel output, override control, valve position control, and decoupling and inferential strategies can be deployed to handle many non-square systems and provide some level of constraint control and optimization. MBC may be difficult to deploy in nonlinear systems which require a high degree of turndown. There are systems like boilers where PID-based solutions are widely used, well understood, and quite effective, which is probably one reason why MBC is seldom applied to
them. So while I am actually an advocate of MBC, I will play devil's advocate here and suggest we never say never.


Lou Heavner
Emerson Process Management