Introduction to Feedback Control Systems
Control deals with the modeling of a variety of dynamic systems and the design of controllers that will ensure that these systems perform in a desired manner. In Chapters 5 through 7, we discussed how to derive a mathematical model for a dynamic system, which can be mechanical, electrical, electromechanical, fluid, or thermal. In this chapter, we focus on how to design a controller for a dynamic system based on its mathematical model. Basic concepts such as feedback, open-loop control, closed-loop control, and basic terminologies in control are introduced in Section 10.1. In general, there are two main reasons why control is needed: one is to maintain the system stability and the other is to improve the system performance. Section 10.2 covers how to determine the stability, how to define the performance in either time domain or frequency domain, and how to identify the model of a system. Section 10.3 discusses the advantages of feedback control, which is utilized in most cases. Following the overview of feedback in Section 10.3, the classical structure of proportional, integral, and derivative control is introduced in Section 10.4. Three different control design methods based on root locus, Bode plot, and state variable feedback are presented in Sections 10.5 through 10.7, respectively. The chapter concludes with controller design and implementation using MATLAB®, Simulink®, and Simscape™ computer tools.