Model-based synthesis of nonlinear PI and PID controllers

PI and PID controllers continue to be popular methods in industrial applica tions. It is well known that linear PI and PID controllers result fi-om the application of model-based controller design methods to linear first- and second-order systems. It is shown that nonlinear PI and PID controllers res ult from the application of nonlinear controller design methods to nonlinea r first- and second-order systems. As a result, the controllers resulting f rom nonlinear model-based control theory are put in a convenient form, more amenable to industrial implementation. Additionally, the quantities used i n the controller are useful for monitoring the process and quantifying mode ling error. Chemical engineering examples are used to illustrate the result ing control laws. A simulation example further demonstrates the performance of the nonlinear controllers, as well as their useful process monitoring q uantities.