PID–PD Control

An effective and simple way of designing a two-degree-of-freedom control scheme for an integral process is to employ an inner feedback loop in order mainly to stabilise the system and then an outer feedback loop in order to provide the required performance. Different methods have been proposed in the literature for the design and tuning of this control scheme, where the controllers are of P(D) type for the internal loop and of PI(D) type for the external loop. These methods will be presented and compared in this chapter.