Robust Digital Controller Design Methods

In this chapter the design of model based robust digital controllers is discussed. The design of digital PID controllers is first presented, emphasizing the general structure of digital controllers (three branched structure known as RST), the special features of the digital approach and the limitations of the digital PID. The following design methods are then presented: pole placement, tracking and regulation with independent objectives and tracking and regulation with internal model control. The presentation is done from the perspective of robust control. These methods permit the control of systems of any order with or without time delay. The last section of the chapter presents a general methodology for the design of robust digital controllers by means of sensitivity functions shaping.