You can expect good results. I tried that for a CSTR system. However, the results are bad in case of an external disturbance. This is expected also.

All what I claimed is just a result of a simulation study. Nothing is proved theoretically.

Hi Dr. Ibraheem,

This sounds like a trick question from a control theorist.

Generally, if the nonlinear system can be approximated as a 2nd-order model and its behavior within a certain operating range of an equilibrium point is weakly nonlinear, then you may expect satisfactory performance from a PID controller that is tuned for good disturbance rejection.

Hi everybody,

thanks for your valuable answers.