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Ebook Modern control systems (11th edition): Part 2

(BQ) Part 2 book "Modern control systems" has contents: The root locus method, frequency response methods, stability in the frequency domain, the design of state variable feedback systems, robust control systems, digital control systems. | CHAPTER 7 The Root Locus Method 7.1 Introduction 7.2 The Root Locus Concept 408 7.3 The Root Locus Procedure 7.4 Parameter Design by the Root Locus Method 7.5 Sensitivity and the Root Locus 408 7.6 Three-Term (PID) Controllers 7.7 Design Examples 413 431 437 444 447 7.8 The Root Locus Using Control Design Software 7.9 Sequential Design Example: Disk Drive Read System 458 7.10 Summary 463 465 PREVIEW The performance of a feedback system can be described in terms of the location of the roots of the characteristic equation in the s-plane. A graph showing how the roots of the characteristic equation move around the s-plane as a single parameter varies is known as a root locus plot. The root locus is a powerful tool for designing and analyzing feedback control systems. We will discuss practical techniques for obtaining a sketch of a root locus plot by hand. We also consider computer-generated root locus plots and illustrate their effectiveness in the design process. We will show that it is possible to use root locus methods for controller design when more than one parameter varies. This is important because we know that the response of a closed-loop feedback system can be adjusted to achieve the desired performance by judicious selection of one or more controller parameters. The popular PID controller is introduced as a practical controller structure with three adjustable parameters. We will also define a measure of sensitivity of a specified root to a small incremental change in a system parameter. The chapter concludes with a controller design based on root locus methods for the Sequential Design Example: Disk Drive Read System. DESIRED OUTCOMES U p o n completion of Chapter 7, students should: Zi J J _l 3 Understand the powerful concept of the root locus and its role in control system design. Know how to sketch a root locus and also how to obtain a computer-generated root locus plot. Be familiar with the PID controller as a key element