Description
Approach
Control systems are an integral part of everyday life in today’s society. They control our appliances, our entertainment centers, our cars, and our office environments; they control our industrial processes and our transportation systems; they control our exploration of land, sea, air, and space. Almost all of these application use digital controllers implemented with computers, microprocessors, or digital electronics. Every electrical, chemical, or mechanical engineering senior or graduate student should therefore be familiar with the basic theory of digital controllers.
This text is designed for a senior or combined senior/graduate-level course in digital controls in departments of mechanical, electrical, or chemical engineering. Although other texts are available on digital controls, most do not provide a satisfactory format for a senior/graduate-level class. Some texts have very few examples to support the theory, and some were written before the wide availability of computer-aided-design (CAD) packages. Others make some use of CAD packages but do not fully exploit their capabilities. Most available texts are based on the assumption that students must complete several courses in systems and control theory before they can be exposed to digital control. We disagree with this assumption, and we firmly believe that students can learn digital control after a one-semester course covering the basics of analog control. As with other topics that started at the graduate level—linear algebra and Fourier analysis to name a few—the time has come for digital control to become an integral part of the undergraduate curriculum.
Features
To meet the needs of the typical senior/graduate-level course, this text includes the following features:
Numerous examples. The book includes a large number of examples. Typically, only one or two examples can be covered in the classroom because of time limitations. The student can use the remaining examples for self-study. The experience of the authors is that students need more examples to experiment with so as to gain a better understanding of the theory. The examples are varied to bring out subtleties of the theory that students may overlook.
Extensive use of CAD packages. The book makes extensive use of CAD packages. It goes beyond the occasional reference to specific commands to the integration of these commands into the modeling, design, and analysis of digital control systems. For example, root locus design procedures given in most digital control texts are not CAD procedures and instead emphasize paper-and-pencil design. The use of CAD packages, such as MATLAB®, frees students from the drudgery of mundane calculations and allows them to ponder more subtle aspects of control system analysis and design. The availability of a simulation tool like Simulink® allows the student to simulate closed-loop control systems including aspects neglected in design such as nonlinearities and disturbances.
Coverage of background material. The book itself contains review material from linear systems and classical control. Some background material is included in appendices that could either be reviewed in class or consulted by the student as necessary. The review material, which is often neglected in digital control texts, is essential for the understanding of digital control system analysis and design. For example, the behavior of discrete-time systems in the time domain and in the frequency domain is a standard topic in linear systems texts but often receives brief coverage. Root locus design is almost identical for analog systems in the s-domain and digital systems in the z-domain. The topic is covered much more extensively in classical control texts and inadequately in digital control texts. The digital control student is expected to recall this material or rely on other sources. Often, instructors are obliged to compile their own review material, and the continuity of the course is adversely affected.
Inclusion of advanced topics. In addition to the basic topics required for a onesemester senior/graduate class, the text includes some advanced material to make it suitable for an introductory graduate-level class or for two quarters at the senior/graduate level. We would also hope that the students in a singlesemester course would acquire enough background and interest to read the additional chapters on their own. Examples of optional topics are state-space methods, which may receive brief coverage in a one-semester course, and nonlinear discrete-time systems, which may not be covered.