control theory - Principle of Automatic Control...

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Introduction Principle of Automatic Control CHAPTER 7 requency Response (P244 Ch 8) By Hui Hui Wang Wang Frequency Response (P.244, Ch.8) 浙江大学控制科学与工程学系
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Introduction Outline of Chapter 7 9 troduction Introduction 9 Bode Plots (Logarithmic plots) 9 Direct Polar Plots 9 yquist’s Stability Criterion Nyquist s Stability Criterion 9 Phase Margin and Gain Margin and Their Relation to Stability 9 ……… 2
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Introduction Frequency Response: 1. Introduction The two basic methods for predicting and adjusting a system’s erformance: performance: ¾ The root-locus methods Advantage: 9 It displays the location of the closed-loop poles as a parameter (gain) is varied 9 It explicitly gives information about transient performance The actual time response is easily obtained by means of the inverse Laplace transform because the precise root locations are known. Disadvantages: 9 It does not provide steady state performance information 9 It cannot handle constraints on frequency ranges for measurement noise and disturbance rejection j Need a new tool to address these issues 3
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Introduction Frequency Response: 1. Introduction ¾ The frequency-response method ---- a good complement to Root Locus 9 We can infer stability and performance, namely steady state performance, from the same plot 9 It is easy to include constraints on frequency ranges 9 Permit evaluation of the effect of noise, exclude the noise by designing a passband and therefore improve the system performance 9 Can use measured data when no model is available (also good for system identification) i d l h dl d tl t t t l 9 Time delays are handled correctly, contrary to root locus 9 Analysis and design techniques are graphical (asymptotic lines) and easy to use 4
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Introduction Frequency Response: 1. Introduction this chapter: In this chapter: ¾ Two graphical representation of transfer functions are presented: ± the logarithmic (对数的) plots ± the polar (极坐标的) plots.
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This note was uploaded on 12/01/2011 for the course EE 400 taught by Professor Hui during the Spring '11 term at Zhejiang University.

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control theory - Principle of Automatic Control...

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