chee 319 process dynamics and control - queen's...

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CHEE 319CHEE 319Process Dynamics and ControlProcess Dynamics and Control

Winter 2012Winter 2012

Instructor:Instructor:M.GuayM.Guay

TAs: S. Dougherty, D.TAs: S. Dougherty, D. Park and E.Park and E. MoshksarMoshksar

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OrganizationOrganization

Instructor: Dr. Martin Guay Office: Dupuis 406 Phone: 533-2788 Email: [email protected] Web: http://chee.queensu.ca/courses/CHEE319/

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ScheduleSchedule

Lectures: (DUN 14 (for today only), JEF 127)

Monday 10:30 – 11:20 Wednesday 9:30 – 10:20 Friday 8:30 – 9:20 Tutorials:

Section A (DUP 244) Friday 9:30 – 10:20 Section B (DUP 244) Friday 10:30 – 11:20

Office Hours (MG): Monday 15:30 – 17:00 (Tentative) Tuesday 15:30 – 17:00

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ReferencesReferences

All lectures will be available onlineAll lectures will be available online Derivations will be done on the boardDerivations will be done on the board Powerpoint Powerpoint slides are to support lecturesslides are to support lectures

Textbook (highly recommended)Textbook (highly recommended)

D.E. D.E. SeborgSeborg, T.F. Edgar, D.A. , T.F. Edgar, D.A. MellichampMellichamp, , Process Dynamics andProcess Dynamics andControl (2nd or 3rd Edition)Control (2nd or 3rd Edition), Wiley, NJ (2003, 2009)., Wiley, NJ (2003, 2009).

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GradingGrading

Grading Midterm (TBDIC) 25% Assignments 15% Final Exam 60%

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GuidelinesGuidelines

i) Assignments

Problems will be assigned every week. Although they will not bemarked, weekly tutorials will be concentrated on the solution of theproblems and on questions that may arise from the course.

Collaboration is encouraged throughout the course. It is recommendedthat the students develop their own individual solutions.

There will be a set of assignments that will be marked. They are to becompleted in groups of 4-5. With one assignment per group.

ii) Exams

Midterm exam will be open-book. Textbooks, course notes andassignments will be allowed. The final will be closed-book.

The timing of the midterm exam will be decided in class. (Likely tobe after reading week.)

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Course ObjectivesCourse Objectives

By the end of this course the student should be able to:

derive transfer function models from process models andprocess data

recognize important process dynamic features of SISO lineardynamical systems

apply modern control theory to design a controller foruncertain SISO linear dynamical systems

understand the trade-off in performance that arise in thedesign of a controller

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Teaching Approach and ExpectationsTeaching Approach and Expectations

Each student is ultimately responsible for learning thematerial in a course. Every professor is responsible forpresenting the course material in a manner that facilitateslearning as much as possible for the class as a whole.

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In fulfilling this contract, I expect that you will activelyand constructively participate in the course. ask questions whenever something is not clear, help each other understand the course material, perform all assigned reading on time, arrive on-time for class, be courteous to each other and myself, provide me with feedback / suggestions as to how the course and

my delivery can be improved.

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In return you should expect me to: treat each of you with courtesy and respect, be committed to help you understand and master the course

material, by being available for out of class assistance, by providing competent teaching assistants, by working to continually improve the course, treat each question or concern seriously and answer these to the

best of my ability.

Class discussions and student participation are encouragedas much as possible, in and out of the classroom

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Course OutlineCourse Outline

1. Introduction2. Modeling for control3. Solution of Linear ODEs using Laplace transforms4. Transfer function models of mechanical systems5. Analysis of Continuous-time Linear Systems6. SISO Control System Analysis7. Synthesis of SISO Controllers8. SISO Controller Design

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IntroductionIntroduction

Feedback systems are commonplace in almost every aspect of lifeFeedback systems are commonplace in almost every aspect of life Standing, walking, running Standing, walking, running etcetc…… are all forms of control systems whereare all forms of control systems where

thethe centralcentral nervous system reacts to variousnervous system reacts to various biosensor mechanismsbiosensor mechanisms Gene regulation is controlled by complex responses that trigger variousGene regulation is controlled by complex responses that trigger various

biological mechanismsbiological mechanisms

In engineering applications, feedback systemsIn engineering applications, feedback systems arise in the designarise in the design ofofcontrol systemscontrol systems Aircraft flight control, sAircraft flight control, satellite altitude controlatellite altitude control Automotive controlAutomotive control Communication systemsCommunication systems RoboticsRobotics Manugfacturing Manugfacturing systems and industrial process systems and industrial process cotnrolcotnrol

Control is the Control is the hidden technologyhidden technology ItIt’’s everywhere, buts everywhere, but hidden by the machinery.hidden by the machinery.

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Feedback systems: Interconnection of two systemsFeedback systems: Interconnection of two systems

E.g.E.g. Glucose concentration regulation:Glucose concentration regulation: System 1 is the liverSystem 1 is the liver SystemSystem 2 is the pancreas2 is the pancreas the output of interest, , is glucose concentration the output of interest, , is glucose concentration the input of interest,the input of interest, , is insulin release rate, is insulin release rate

System 1

System 2

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ControlControl

A controller is a system designed to regulate a given process Process typically obeys physical and chemical conservation laws Controller obeys laws of mathematics and logic (sometimes

intelligent)

e.g. - Riding a bike (human controller)- Driving a car- Automatic control (computer programmed to control)

Process

Controller

What is a feedback controller?

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ControlControl

A controlled process is a system which is comprised of two interactingsystems:

e.g. Most controlled systems are feedback control systems

The controller is designed to provide regulation of process outputs in thepresence of disturbances

Process

Controller

OutputsDisturbances

Action Observation

monitorintervene

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Classical Feedback ControlClassical Feedback Control

Control is meant to provide regulation of process outputs about areference, r, despite inherent disturbances

The deviation of the plant output, e=(r-y), from its intended referenceis used to make appropriate adjustments in the plant input, u

Classical Feedback Control System

ProcessController

d

yur e+-

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Feedforward Feedforward ControlControl

Feedforward Feedforward control is used to remove the effect ofcontrol is used to remove the effect ofmeasurable disturbancesmeasurable disturbances

A PCff

MDisturbance

NominalInput

CorrectedInput

++

InputCorrection

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Open-loop Open-loop vsvs.. Closed-loopClosed-loop

Feedback control is an example of closed-loop control:Feedback control is an example of closed-loop control: The process output is sent back to the controller before affectingThe process output is sent back to the controller before affecting

the processthe process

Open-loop controlOpen-loop control

Controller affects the behavior of Process in a non reactive wayController affects the behavior of Process in a non reactive way

Process

Control

ProcessControl

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HistoricalHistorical PerspectivePerspective Control goes back to the 19thControl goes back to the 19th centurycentury

Central theme in many important areasCentral theme in many important areas

Major impact in fMajor impact in flight controllight control

““We know how to construct airplanes.We know how to construct airplanes. Men also know how to buildMen also know how to buildengines. engines. Inability to balance and steer still confronts students ofInability to balance and steer still confronts students ofthe flying problemthe flying problem. When one feature has been worked out, the. When one feature has been worked out, theage of flying will have arrived,age of flying will have arrived, for all other difficulties are offor all other difficulties are ofminor importance.minor importance.””

Wilbur Wright (1901)Wilbur Wright (1901)

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Historical PerspectiveHistorical Perspective

History of flight control is a testament to the importance ofHistory of flight control is a testament to the importance ofcontrol theorycontrol theory

Wright BrothersWright Brothers 19031903 SperrySperry’’s Autopilots Autopilot 19121912 V1 and V2 (A4)V1 and V2 (A4) 19421942 Robert E. LeeRobert E. Lee 19471947 SputnikSputnik 19571957 ApolloApollo 19691969 Mars PathfinderMars Pathfinder 19971997

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ExamplesExamples

e.g. Landing on Mars

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TheThe feedback amplifierfeedback amplifier Invented by Black (1928) to improve signal strengthInvented by Black (1928) to improve signal strength

Enables telephone calls over long distancesEnables telephone calls over long distances

Open-loop amplificationOpen-loop amplification

BecomesBecomes

AmplificationAmplification of the feedback amplifier depends on feedback gainof the feedback amplifier depends on feedback gain

OutputInput +

-

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TheThe invention of the feedback amplifierinvention of the feedback amplifier is fundamentalis fundamental

FormsForms the basis for the design of world wide telephone/televisionthe basis for the design of world wide telephone/televisionnetworksnetworks

Confirms the importance of feedback system designConfirms the importance of feedback system designNyquist Nyquist stability theoremstability theorem 19321932BodeBode’’s s work on feedback designwork on feedback design 19401940

Provides the framework for modern control system theory andProvides the framework for modern control system theory andcontrol system designcontrol system design

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By 1940, theBy 1940, the magic of feedback was understoodmagic of feedback was understood An extra component to be considered forAn extra component to be considered for process design to:process design to:

Keep key variables constantKeep key variables constantStabilize unstable systemsStabilize unstable systemsReduce the effects of disturbancesReduce the effects of disturbances andand process variationsprocess variations

Main drawback: can de-stabilize stable processesMain drawback: can de-stabilize stable processes

Principles of feedback applied in:Principles of feedback applied in: Power electronicsPower electronics Industrial process controlIndustrial process control Flight controlFlight control TelecommunicationsTelecommunications

But, the similarities between all applications were not understood yet.But, the similarities between all applications were not understood yet.

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From 40s, a new field emergesFrom 40s, a new field emerges Similarities between applications are understood leading to theSimilarities between applications are understood leading to the

uunification ofnification ofSolid theoretical frameworkSolid theoretical frameworkSound designSound design methodologymethodologyDesign principlesDesign principlesApplicationsApplications

Modern Control systemsModern Control systems Well established body of ideas, concepts, theory and designWell established body of ideas, concepts, theory and design

methods.methods. Wide and growing scope of applicationsWide and growing scope of applications Remains a very active area of research and developmentRemains a very active area of research and development……

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In engineering applications, the design of a control system is essential toensure: Good Process OperationGood Process Operation Process SafetyProcess Safety Product QualityProduct Quality Minimization of Environmental ImpactMinimization of Environmental Impact

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What is the purpose of a control system?What is the purpose of a control system?

“To maintain important process characteristics at desired targetsdespite the effects of external perturbations.”

Control

PlantProcessingProcessingobjectivesobjectives

SafetyMake $$$

Environment...

PerturbationsPerturbations

MarketEconomyClimateUpsets...

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Dynamics:

Study of the transient behavior of processes

Control:

the use of process dynamics for the improvement of processoperation and performance

the use of process dynamics to alleviate the effect of undesirable(unstable) process behaviors

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What do we mean by process, plant or system?

A process (plant or system), , is an operation that takes an INPUT or aDISTURBANCE and gives an OUTPUT

INPUT: ( ) Something that you can manipulate DISTURBANCE: ( ) Something that comes as a result of some outside

phenomenon OUTPUT: ( ) An observable quantity that we want to regulate

Information Flow

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ExamplesExamples

The speed of an automobile

Force ofEngine

AerodynamicFriction

Inputs OutputFriction

EngineSpeedProcess

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ExamplesExamples

Stirred tank heater

MTin, w

Q

T, w

TinwQ

TProcess

InputsInputs Output

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Block representationsBlock representations

Block diagrams are models of the physical systems

Process

System Physical Boundary Transfer of

fundamental quantities

Mass, Energy and Momentum

Input variables Output variables

Physical

OperationAbstract

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What is required for the development of a control systemWhat is required for the development of a control system??

1. Process UnderstandingRequired measurementsRequired measurementsDynamic modelDynamic modelRequired actuatorsRequired actuatorsUnderstand design limitationsUnderstand design limitations

2. Process InstrumentationAppropriate sensor and actuator selectionAppropriate sensor and actuator selectionIntegration in control systemIntegration in control systemCommunication and computer architectureCommunication and computer architecture

3. Process ControlAppropriate control strategyAppropriate control strategy

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ExamplesExamples

Measure , adjust

Controller:where

Q: Is this positive or negative feedback?

Thermocouple

Feedback control

AC P

M

Controller

Tank-

+Heater

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ExampleExample

Cruise Control

Controller

FrictionProcess SpeedEngine

Human or Computer

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Classical ControlClassical Control

Control is meant to provide regulation of process outputs about areference, r, despite inherent disturbances

The deviation of the plant output, e=(r-y), from its intended referenceis used to make appropriate adjustments in the plant input, u

Classical Feedback Control System

ProcessController

d

yur e+-

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ControlControl

Process is a combination of sensors and actuators

Controller is a computer (or operator) that performs the requiredmanipulations

e.g. Classical feedback control loop

yr eAC P

M

dComputer Actuator

Process

Sensor

-+

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ExamplesExamples

Driving an automobile

yeAC P

M

Driver

Automobile-

+Steering

r

Visual and tactile measurement

Desired trajectoryr

Actual trajectoryy

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ExamplesExamples

Stirred-Tank Heater

Q T, wHeater

TCThermocouple

Tin, w

TR

Tin, w

yeAC P

M

Controller

Tank-

+Heater

Thermocouple

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ExamplesExamples

Measure Ti, adjust Q

A PC

MTi

Qi

ΔQQ

++

Feedforward Control

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Feedforward Feedforward ControlControl

Feedforward Feedforward control is used to remove the effect ofcontrol is used to remove the effect ofmeasurable disturbancesmeasurable disturbances

A PCff

MDisturbance

NominalInput

CorrectedInput

++

InputCorrection

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Control NomenclatureControl Nomenclature

Identification of all process variables

Inputs (affect process)Outputs (result of process)

Inputs

Disturbance variablesVariables affecting process that are due to external forces

Manipulated variablesThings that we can directly affect

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Control NomenclatureControl Nomenclature

OutputsMeasured

speed of a carUnmeasured

acceleration of a car Control variables

important observable quantities that we want to regulatecan be measured or unmeasured

Controller

Manipulated

Disturbances

Process Control

Other

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ExamplesExamples

The speed of an automobile

VariablesVariables Engine force: uEngine force: u Car speed: vCar speed: v Friction force: Friction force: fffricfric Aerodynamic forces: Aerodynamic forces: ffaeroaero Road inclination:Road inclination:

Force ofEngineFriction

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ExampleExample

Variables Inputs Outputs

Disturbances Manipulated Measured Unmeasured Control

Task: Classify the variables

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ExampleExample

T

L

T

wi, Ti

wc, Tci

wc, Tco

wo, To

h

Variables

• wi, wo: Tank inlet and outlet mass flows• Ti, To: Tank inlet and outlet temperatures• wc: Cooling jacket mass flow• Pc: Position of cooling jacket inlet valve• Po: Position of tank outlet valve• Tci, Tco: Cooling jacket inlet and outlet

temperatures• h: Tank liquid level

Po

Pc

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ExampleExample

Variables Inputs Outputs Disturbances Manipulated Measured Unmeasured Control

wiTiTciwchwoToPcPo

Task: Classify the variables

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Process Control and ModelingProcess Control and Modeling

In designing a controller, we mustDefine control objectivesDevelop a process modelDesign controller based on model Test through simulation Implement to real process Tune and monitor

Model

Controlleryur e

d

Process

DesignImplementation

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Control System DevelopmentControl System Development

Define Objectives

Develop a process model

Design controller based on model

Test bySimulation

Implement and Tune

MonitorPerformance

Control development is usually carried out following these important steps

Often an iterative process, based on performance we may decide to retune, redesign or remodel a given control system

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Objectives “What are we trying to control?”

Process modeling “What do we need?”

Mechanistic and/or empirical

Controller design “How do we use the knowledge of process behavior to reach our process

control objectives?” What variables should we measure? What variables should we control? What are the best manipulated variables? What is the best controller structure?

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Implement and tune the controlled process Test by simulation incorporate control strategy to the process hardware theory rarely transcends to reality tune and re-tune

Monitor performance periodic retuning and redesign is often necessary based on

sensitivity of process or market demands statistical methods can be used to monitor performance

chee 319 process dynamics and control - queen's...

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