Process Control: Modeling, Design, and Simulation

9.7. Summary

We have shown how the IMC procedure can be used to design PID-type feedback controllers. If the process has no time delay and the inputs do not hit a constraint, then the IMC-based PID controllers will have the same performance as does IMC. If there is dead time, then the IMC-based PID controllers will not perform as well as IMC because of the Padé approximation for deadtime.

Table 9-3. PID Tuning Parameters for Unstable Processes

	gp(s)	gCL(s)	kc	τI	τD	Notes[a]
A			γ		1
B	γ + τp	1
C	γ		1, 2

^[a] 1, . 2, PI cascaded with a lead-lag filter, .

It is interesting ...