Tuning Rules for Lag Dominated FOPDT (first-order plus deadtime) model

[Will26040]

Homework Statement

What would be a good tuning rule for use of the following FOPDT transfer function with a PI controller? (apart from SIMC, direct synthesis, Cohen and Coon or Ziegler Nichols)

Relevant Equations

$\frac {27e^{-3s}} {30s+1}$

I am trying to find an alternative tuning rule for use with the transfer function specified. Please could someone help by pointing me in the right direction, thanks.

Process transfer function:

$\frac {27e^{-3s}} {30s+1}$

Also, am I right in thinking that this process transfer function is lag dominated?

 

[Valkarie]

Yes, this process transfer function is lag-dominated. Lag-dominant process transfer functions are usually tuned using the Ziegler-Nichols (ZN) or the Cohen-Coon (CC) methods. Both these methods involve adjusting the proportional gain (Kp) and reset time (tau) to achieve an optimal response. The ZN method uses the ultimate gain (Ku) and ultimate period (Pu) of the process as input parameters, while the CC method uses the rise time (tr) and percent overshoot (Mp) as input parameters. You can find more information about these two tuning rules here: https://www.schneider-electric.com/en/faqs/FA234037/.