# Lecture 7.1: Loop Analysis of Feedback Systems

#### 11 November 2002

 Lecture Reading FAQ Homework CDS 101

### Lecture

This lecture describes how to analyze the stability and performance of a feedback system by looking at the open loop transfer function. We introduce the Nyquist criteria for stability and talk about the gain and phase margin as measures of robustness. The cruise control system is used as an example throughout the lecture.

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#### Handouts from lecture

The following materials were handed out in lecture. These have been updated to include any corrections.

### Homework

This homework set covers stability and robustness using the Nyquist criterion. The first problem consists of two sample systems for which gain and phase margin should be computed using both Nyquist and Bode plots. The second problem investigates the stability and performance of the cruise control system under different PI controllers. The CDS 110 questions explore the stability and control of a simple disk drive positioning system and the ducted fan.

• 11 Nov 02: problem set release

Frequently asked questions on homework and TA hints: