EEL 6619 - Robust Control

Fall 2005



Course Objectives and Overview

This course is devoted to the study of topics in the area of Robust Control Theory. Robust control is defined as the control of uncertain plants - that is, systems with uncertain dynamics or unknown disturbance signals, using fixed deterministic controllers. This area in control theory flourished in the late 70's and is still very active in producing new results. The course deals with different transfer matrix, Nyquist and Nyquist-like techniques for robust control and several techniques and algorithms are compared. Seve ral MATLAB based problems are assigned to facilitate better understanding of the results developed in this course. These assignments also facilitate the learning of the powerful toolboxes of MATLAB: namely, control sytem, robust control and ?synthesis tool boxes. Robust control has wide applications in VLSI manufacturing technology, circuit design (the circuit elements have tolerances which we call uncertainties), automotive and aerospace appplications, chemical processing technology and several other control-centric application areas.

Introductory material is first presented on the sources of uncertainties in system modeling and particular motivation is given to the main classes of uncertainties encountered in the robust control literature as well as in general practice. The use of singular value techniques in the analysis of robust control system is then motivated and developed, first with reference to the general class of the so-called unstructured uncertainties and also with respect to a broad class of structured uncertainties. Using frequency response stability results of the Generalized Nyquist Criterion as a starting point, the effects of system uncertainties are incorporated as a perturbation about the nominal system description. The development provides a generalization of the Characteristic Locus Method for the case of uncertain systems via the E-contours and also gives a development of robustness analysis and design using the scaled singular values.

We also consider the question of real perturbations as these arise, for example, from a consideration of the uncertainties in the state space of both single-input single-output (SISO) and multi-input multi-output (MIMO) systems. It is shown that this problem may be cast as an equivalent frequency domain problem and is solved as such. The highly structured class of parametric uncertainties is introduced and the robust stability problem is solved by a new and elegant method called critical perturbation radius method, which is currently a main area of interest of the robust control group. A comparison of conservatism, computational burden, and efficiency with other techniques is also made, facilitating in-class interactions. Recent publications on these topics are discussed in the class, giving up-to-date information in the field and encouraging students to do a literature survey and even come up with their own research ideas in this field.

The final section of the course gives an introduction to optimal H-infinity, ?synthesis methods.

Catalog Description

Stability and Performance Analysis of MIMO and SISO systems in the presence of Uncertainties.

Course Goal

To provide advanced students in the systems and controls area an exposure to the methods of analysis required to evaluate robustness of mutlivariable systems to system uncertainties and disturbances.

Prerequisites

An undergraduate course in Classical Control systems is required and some exposure to state variable methods is also desirable background for some of the material to be covered in the course. Specifically, it would be helpful for students to have a sound grasp of transform theory, elementary linear algebra and matrix theory.

Course Materials

Textbook: Frequency Response Methods for Uncertain Multivariable Systems, Haniph A. Latchman, Course Notes. Additional reading material are listed below.

Electronic copies of the course syllabus, notes and other course information will be accessible via the World Wide Web (WWW) at the following URL http://latchman.list.ufl.edu. Select EEL 6619 from the FALL 2002 courses. Course notes and problem solutions will be distributed in hardcopy format in class and posted electronically as indicated above.

Grading

Grades are based on the following weights.

Participation

In this class a formal grade will be assigned for active participation in class-time and online activities. This will foster an active learning mode as well as fruitful collaborative learning among students. Details of the type of participation expected will be provided in class. Final letter grades will be assigned at the end of the semester and will depend on absolute and relative student and class performance.

Assignments

Homework and other assignments will be given periodically and will be due within the first 5 minutes of class on the designated due-date. FEEDS/NTU students will have a one (1) week extension on all assignment due dates.Use regular-size paper, staple the sheets together and put your name and homework number at the top. Late homework will be accepted only in exceptional circumstances which need to be discussed with the Instructor for approval. Graded homework will be returned in class and/or placed in the shelves near the elevators on the 4th floor of the New Engineering Building.

Exams

The midterm exam and the final exam will be given in class and dates for these will be announced in class. The final exam will be comprehensive, but with emphasis on material covered since the midterm exam. An announcement will be made to indicate whether the examinations will be closed-book, open-book or limited-notes.

Final Project

All students will be required to complete a final project or research paper as part of the requirements of this course. The project may take the form of a programming project, a simulation or other quantitative experimental study, a critical review a relevant paper, or some combination of these. The project may be done individually or in teams of two or more students, provided that the work is compartmentalized to clearly identify the contribution of each participant. All projects must deal with some aspect of robust control. It is preferred that students select a project that is of interest to them and one that can be completed in a timely manner using readily available resources. In some cases, the resources of the Laboratory for Information Systems and Telecommunications (LIST) may be used, especially if the selected project is relevant to on-going LIST research. The project must be completed in the allotted time; incomplete grades will not be given just to allow extra time to work on the project. All projects must be approved by the instructor. Each student or team must submit a brief project proposal (about 1 page in length) that outlines project objectives, required resources, work plan, and deliverables. Project proposals are due within the first three weeks of classes. You are encouraged to discuss project ideas with the instructor and to submit your proposal as early as possible. If a student cannot find an appropriate topic, one will be assigned.

Examples of Projects

Project Reports

Project reports should be presented in a professional manner. Students working in teams may submit multiple reports or a single report as agreed with the instructor on project approval. All reports must be typed and neatly formatted. A cover page that indicates project title, course, student name(s) and ID number(s) and date, must be included. Final reports should be formatted according to the standard IEEE Journal paper format. A sample will be provided. Variations from this format must be approved by the Instructor. Neatness, spelling, grammar, writing style, presentation and clarity will be considered in grading. Any texts, papers, manuals, reports, or other sources must be acknowledged using standard IEEE format. Neatly drawn figures and graphs should be used where appropriate. Target lengths for the project report is about 15-20 pages. Please do not copy material directly from reference sources. Give proper citations for all references and explictly identify the source of direct quotations.

Additional Reading Materials

The following additional reading material may be helpful.

Computer Support

Matlab with the following toolboxs:

Engineering Applications

Aircraft Controller Design, circuit design, VLSI mnufacturing technology, chemical process technology