MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Department of Electrical Engineering and Computer Science
6.302 Feedback Systems
Fall Term 2002

Lectures

Two sessions / week
1 hour / session

Recitations

Two sessions / week
1 hour / session

Introduction

Feedback Systems is quite possibly the most important class you will ever take. Everything needs feedback. You will never design an electronic or an electromechanical system that does not include a feedback loop, either explicitly or implicitly.

Every interface to the real world - whether you are building a robot arm, a temperature control system, an audio power amp, or an RF synthesizer (the list goes on and on) - needs to drive some kind of actuator - a motor, a heater, a power transistor, or an oscillator. To make sure that actuator is doing the right thing, you need to measure the output (its position, its temperature, its voltage, or its frequency) and compare that measurement to what you meant to do. In other words, you need feedback.

Course Content

Introduction to design of feedback systems. Properties and advantages of feedback systems. Time-domain and frequency-domain performance measures. Stability and degree of stability. Root locus method. Nyquist criterion. Frequency-domain design. Compensation techniques. Application to a wide variety of physical systems. Internal and external compensation of operational amplifiers. Modeling and compensation of power converter systems. Phase lock loops.

Reading Material

There is no required text. A set of notes will be provided to you in installments during the term, free of charge.

Kent Lundberg's notes on Feedback Control Systems will be the primary reference for the subject. You will also be given excerpts from notes written by Professors Gould, Markey, Trumper, and Roberge. If you wish to find additional problems or a different slant on the material, the following helpful texts may be found at the library or a used bookstore:

Roberge, J. K. Operational Amplifiers: Theory and Practice. New York, NY: Wiley, 1975. ISBN: 9764423051. (The classic text, used in 6.302 in days of yore. Out of print.)

Nise, N. S. Control Systems Engineering. 3rd ed. New York, NY: Wiley, 2000. ISBN: 0471366013. (Used in 2.010.)

Palm, W. J. Modeling, Analysis, and Control of Dynamic Systems. 2nd ed. New York, NY: Wiley, 1999. ISBN: 0471073709. (Used in 2.003.)

Van de Vegte, J. Feedback Control Systems. 3rd ed. Upper Saddle River, NJ: Prentice Hall, 1993. ISBN: 0130163791. (Used in 16.060.)

Grading Policy

Problem Sets 20%
Labs 1 and 2 20%
Quizzes 20%
Take-Home Quiz 10%
Design Problem 10%
Final Exam 20%

Laboratory

There will be six relatively short laboratory projects during the term. You will be expected to complete the assignments and then demonstrate your mastery of the material in an individual checkout interview that will be scheduled with the teaching assistants. Each lab will be preceded by a prelab assignment that must be turned in before doing the lab work. Prelab calculations and lab write-ups are due in class on the day listed on the assignment sheet. Labs turned in after the due date will not be accepted. Lab work may be carried out by teams of two students.

You will have a five short lab projects and a design problem to do - about one every other week - ranging in subject from operational amplifiers to thermal systems. We hope you find these labs illustrative and informative.

We start the term by studying a servomotor mechanism. There are many good reasons for using motors in these four labs (labs 1A, 1B, 1C, and 1D). Most of all, we believe that it is a valuable experience. In your careers as engineers, the systems you design and build will often interface to the real world with motors, actuators, and sensors of all kinds. We believe that these labs are an excellent introduction to this kind of design.

Lab 2 explores the art of compensation using a model operational amplifier. You will explore the use of resistor and capacitor networks to implement reduced-gain compensation, lag compensation and lead compensation.

In the design problem you will investigate a system that is patterned after one that was developed at Lincoln Laboratory to control the temperature of a laser diode (the color and power of the laser are strong functions of temperature). This system was used in a space-based optical-communication experiment, but could be used in any precise temperature application.

Quizzes and Final Exam

There will be two quizzes given in lecture: Quiz 1 and Quiz 2. Please do not be late to class (in general, but especially so on quiz days). A three-hour comprehensive examination will be scheduled during the final exam period.

The quizzes and the final are likely to include questions about material from the lectures, recitations, problem sets, labs and reading.

Generally, we will not make alternate or make-up arrangements for quizzes and the final. In the event of a sickness or dire emergency, please call us before the quiz or exam to let us know, if possible.

Problem Sets

Problem sets will be issued in recitation and will be due in recitation in the following week. Please start early on the problem sets. Solutions will be handed out in recitation.

Late Assignments and Incompletes

Late labs, late take-home quizzes and late design problems will not be accepted. Thus, incompletes (grades of I) for missing assignments will not be given. The final letter grade will be based on the actual work completed during the term in accordance with the distribution shown on the first page.

Academic Honesty

You are encouraged to collaborate with others on the solution of problem sets. We believe that there is much to be gained when learning is a shared experience, provided that everyone in the group participates. If you do collaborate on problem sets, the final work you hand in should be your own and you should acknowledge (by including their names) others with whom you have worked. If you use other sources ("bibles"), they should also be acknowledged. It is immature and dishonest to copy the work of others (like an old solution or a friend's solution) and submit it as if it were your own. Since problems serve to guide you to develop the skills needed in this subject and your future career, not to do the work yourself is foolish; you will fail the quizzes and exam. Of course, design problems, take-home quizzes, in-class quizzes and finals are to be worked strictly on your own.

Laboratory write-ups (prelab and postlab) must be your own work. The use of bibles for these exercises is strictly prohibited.

Plagiarism or other forms of cheating are intellectually and personally dishonest. Such dishonesty is a severe breach of the Institute's communal standards, as well as those of the engineering profession. Infractions will be dealt with severely.