EES42042 - Fundamental of Control Systems Controller...

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EES42042 - Fundamental of Control Systems

Controller Design via Controller Design via Root LocusRoot Locus

The Industrial Operations HierarchyThe Industrial Operations Hierarchy

Supervision Supervision

Control Control

Process 1 Process 2

Management, Coordination,Optimization

Low

laye

rH

igh

laye

rP

roce

ss

• Estimator management• Controller management• Fault detection• Fault diagnose• Fault isolation

• Adjustment mechanism• Control algorithm: PA,

MPC, deadbeat, MV, Fuzzy, NN, Ackermann

Analysis and Control ObjectivesAnalysis and Control Objectives

Improving steady state errorImproving transient responseStabilityLow costRobustness

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.7 Types of cascade compensators (continued on next slide)

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.7 Types of cascade compensators (continued)

The Relay ExperimentThe Relay ExperimentAutotuningAutotuning PID ControllerPID Controller

-

Process

Disturbancee(t)PID Control

Law

Signal Proc. Unit

PID Control Rule-Base

Relay Block

Referencesignal

w(t)

Controlsignalu(t)

Outputsignaly(t)

SelfSelf--Tuning Control System SchemeTuning Control System Scheme((22--DOF ControllerDOF Controller))

Controlsignal

u(t)

Outputsignaly(t)

-

G(z-1)F(z-1)

Referencesignal

w(t) H(z-1)G(z-1)

Recursiveestimator

Controllersynthesis

Configurationrequirements

Performancerequirements Estimated system

parameters; A, B

Controllerparameters; H, F, G

2-DOF controller

Pressure process rig

Adjustment mechanism

PRBSGenerator

Pole assignment

Deadbeat

RLS

RIV

Figure 9.1a. Sample root locus,showing possibledesign point viagain adjustment (A)and desired designpoint that cannot bemet via simple gainadjustment (B);b. responses frompoles at A and B

IntroductionIntroduction

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.2Compensationtechniques:a. cascade;b. feedback

Figure 9.3Pole at A is:a. on the rootlocus without compensator;b. not on theroot locus withcompensatorpole added;(figure continues)

Improving Steady State ErrorImproving Steady State Error

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.3(continued)c. approximately on the root locus with compensator pole and zero added

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.4Closed-loopsystem forExample 9.1:a. beforecompensation;b. after ideal integralcompensation

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.5Root locus foruncompensatedsystem ofFigure 9.4(a)

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.6Root locus forcompensatedsystem of Figure 9.4(b)

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.7Ideal integral compensated system response and theuncompensated system response of Example 9.1

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.8PI controller

Figure 9.9a. Type 1 uncompensated system;b. Type 1 compensatedsystem;c. compensatorpole-zero plot

Lag CompensationLag Compensation

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.10Root locus:a. before lag compensation;b. after lag compensation

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.11Compensated systemfor Example 9.2

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.12Root locus forcompensated system of Figure 9.11

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.1Predicted characteristics of uncompensated and lag-compensated systems for Example 9.2

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.13Step responses ofuncompensated andlag-compensatedsystems forExample 9.2

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.14Step responses of the system for Example 9.2 using different lag compensators

Figure 9.15Using ideal derivative compensation:a. uncompensated; b. compensator zero at –2;

Improving Transient ResponseImproving Transient Response

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.15 (continued)c. compensator zero at –3; d. compensator zero at – 4

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.16Uncompensated system and ideal derivativecompensation solutions from Table 9.2

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.2Predicted characteristics for the systems of Figure 9.15

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.17Feedbackcontrol systemfor Example 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.18Root locus for uncompensatedsystem shown in Figure 9.17

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.3Uncompensated and compensated system characteristics for Example 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.19Compensateddominant polesuperimposed over the uncompensatedroot locus forExample 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.20Evaluating the location of the compensatingzero for Example 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.21Root locus for thecompensated system of Example 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.22Uncompensated andcompensated system step responses ofExample 9.3

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.23PD controller

Figure 9.24Geometry of leadcompensation

Lead CompensationLead Compensation

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.25Three of the infinitepossible leadcompensator solutions

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.26Lead compensatordesign, showingevaluation ofuncompensatedand compensateddominant poles forExample 9.4

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.4 Comparison of lead compensation designs for Example 9.4

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.27s-plane pictureused to calculatethe location ofthe compensator pole for Example 9.4

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.28Compensated systemroot locus

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.29Uncompensatedsystem and leadcompensationresponses forExample 9.4

Figure 9.30PID controller

PID Controller DesignPID Controller Design

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.31Uncompensated feedback control system for Example 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.32Root locus for theuncompensatedsystem ofExample 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.5Predicted characteristics of uncompensated, PD- , and PID-compensated systems of Example 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.33Calculating thePD compensator zero for Example 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.34Root locus forPD-compensatedsystem ofExample 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.35Step responses foruncompensated,PD-compensated, andPID-compensatedsystems ofExample 9.5

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.36Root locus for PID-compensatedsystemof Example 9.5

Figure 9.37Uncompensatedsystem forExample 9.6

LagLag--lead Compensator Designlead Compensator Design

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.38Root locus for uncompensatedsystem of Example 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Table 9.6Predicted characteristics of uncompensated, lead-compensated, and lag-lead- compensated systems of Example 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.39Evaluating thecompensator pole forExample 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.40Root locus for lead-compensated system of Example 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.41Root locus for lag-lead-compensated systemof Example 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.42Improvement in step response forlag-lead-compensatedsystem ofExample 9.6

Control Systems Engineering, Fourth Edition by Norman S. NiseCopyright © 2004 by John Wiley & Sons. All rights reserved.

Figure 9.43Improvement inramp response error for the system ofExample 9.6:a. lead-compensated;b. lag-lead-compensated