Week 7: Loop Analysis
Overview
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.
Reading Material and Handouts
Handouts from lecture
- Monday lecture handout
- MATLAB files: (none)
- Homework #6
Required reading
-
K. J. Åström and R. M. Murray, Analysis and Design of Feedback Systems, Preprint, 2003. Chapter 7. (Caltech access only).
Supplemental reading
- A. D. Lewis, A Mathematical Introduction to Feedback Control. Chapter 7.
Homework Set
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.