Process Control: Modeling, Design, and Simulation

Chapter 8. Internal Model Control

In Chapter 6 we presented several methods for tuning PID controllers and developed a model-based procedure (direct synthesis) to synthesize a controller that yields a desired closed-loop response trajectory. In this chapter, we first develop an “open-loop control” design procedure that then leads to the development of an internal model control (IMC) structure. There are a number of advantages to the IMC structure (and controller design procedure), compared with the classical feedback control structure. One is that it becomes very clear how process characteristics such as time delays and RHP zeros affect the inherent controllability of the process. IMCs are much easier to tune than are controllers in a standard ...