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EE 302 Introduction to Feedback Systems. CONTENTS. Introduction Transfer Functions Mathematical Models, Transfer fns. and block diagrams, Block Diagram Simplification State Equations State equations from transfer fns., Canonical forms, Controllability and Observability
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EE 302 Introduction to Feedback Systems
CONTENTS • Introduction • Transfer Functions • Mathematical Models, Transfer fns. and block diagrams, Block Diagram Simplification • State Equations • State equations from transfer fns., Canonical forms, Controllability and Observability • Time Domain Analysis • Transient response & Steady state error 1.1 - Introduction
CONTENTS (cont’d) • Stability • Routh-Hurwitz test, Root locus • State Feedback • Pole placement, Observer design • Nyquist Stability Criterion • Nyquist criterion & Relative Stability • Design in Frequency Domain • Phase-lead & Phase-lag compensation 1.1 - Introduction
Introduction: Basic concepts
input output A control system = an interconnection of components that will provide a desired system response 1.1 - Introduction
Process or Plant input More general Mostly mechanical or electrical output 1.1 - Introduction
Process output OPEN-LOOP CONTROL SYSTEMS Controller Desired output response 1.1 - Introduction
Controller Process Desired output response output CLOSED-LOOP (FEEDBACK) CONTROL SYSTEMS Comparison Measurement 1.1 - Introduction
+ Reference I/P elements Controller Process O/P - Feedback elements Comparison is often a difference device Command Reference input Actuating signal Manipulated variable Controlled variable Feedback signal Usually contain converters (tachometers, transducers etc.) 1.1 - Introduction
E R C + G - H BASIC FEEDBACK CONFIGURATION “reference” input actuating error “controlled” output 1.1 - Introduction
E R C + G - H TERMINOLOGY G: Forward path gain H: Feedback gain -GH: Loop gain 1.1 - Introduction
E R C + G - H The return difference EFFECTS OF FEEDBACK:Overall transfer function C=G.E E=R-H.C C=G.R-G.H.C 1.1 - Introduction
EFFECTS OF FEEDBACK:Sensitivity +G C +? G Open-loop system ( H=0 ) C=G.R C+C = (G+G).R ThusC = G.R S=1 Relative change: 1.1 - Introduction
Sensitivity:Closed-loop system (H0) Modified byS=1/return difference 1.1 - Introduction
R C + G -20log(1+K) - K=0 K K=1 K=2 (1+K)a EFFECTS OF FEEDBACK:Bandwidth Let 1.1 - Introduction
Use of feedback modifies • the denominator of the transfer fn • modes (natural frequencies) • stability properties (absolute or relative) • bandwidth • sensitivity • disturbance (noise) reduction properties 1.1 - Introduction
End of Section Next section Restart section Next chapter Restart chapter i The End General index End show 1.1 - Introduction