Simulink-02-01.ppt

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Department of Mechatronics Engineering

Wahyudi Martono, Dr. Eng.Department of Mechatronics EngineeringInternational Islamic University Malaysia

Module IV:SIMULINK and Neuro-Fuzzy Toolboxes

MATLAB & SIMULINKwith Applications

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Session 2:Getting Started with Simulink

SIMULINK

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Session Outlines

Subsytems

Masking

Discrete System

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Subsystems

What is Subsystems?We may make a very complex system resulting in a verycomplex model.

As subprogram (subroutine or function) of otherprogramming language, Simulink provides an analogouscapability called subsystems.

Using subsystems, we can make the models easier to

develop, to understand and to maintain.

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Subsystems

Method of Creating Subsystems

There are two method for creating subsystems:

Encapsulating a SubsystemA portion of existing model is encapsulated to bea subsystem.

Use Subsystem blocks from Signals & System

Library.

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Subsystems

Encapsulating SubsystemsSuppose we want to make our primitive model of mass-spring-damper as a subsystem.

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Subsystems

Encapsulating SubsystemsTo encapsulate a portion of a Simulink model, select allthe blocks and signal line to be included in thesubsystem using a bounding box using our mouse.

bounding box

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Subsystems

Encapsulating SubsystemsChoose Create Subsystemunder Editmenu.

New subsystem

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Subsystems

Encapsulating SubsystemsTo view or edit a subsystem, double-click the block. Anew window will appear.

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Subsystems

Subsystems BlocksIf, when building a model, we know that we will need asubsystem, it will more convenient to build a subsystemin a subsystem directly.

Drag a Subsystem Blockfrom Ports & Subsystem

Library to the model window.

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Subsystems

Subsystems BlocksDouble click the subsystem to open subsystem window.

Build subsystem using the standard procedure.

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Subsystems

Subsystems Blocks

Use Inport Blocks for all signals entering subsystem andOutport Blocks for all signals leaving the subsystem.(Both blocks are from Port & Subsytem Library)

You may change the label of Inport and Outpor. Closethe subsystem window if we finished building subsystem.

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Masking

Concept

Masking permits us to treat a subsystem as if it was asimple block.

A mask is a custom user interface for a subsystemthat hides the subsystems contents, making it appear

to the user as an atomic block with its own icon andparameter dialog box.

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Masking

Concept

We make a masked subsystem for the following reason:There is an algorithm which we want to hide from

other user. To prevent unintended modification of subsystems byhiding their contents behind a mask

Lets build a spring-mass masked block.

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Masking

Open a new model workspace, and drag the subsystemof the primitive model into it.

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Masking

Select the subsystem model and then choose Maskunder Editmenu from the new model window menu bar.

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Masking

Mask Editor dialog box consists of four tabbed pagesIconInitializationParameters

Documentation

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Masking

Mask Editor Documentation Page

The page consists of threefield. All of the fields areoptional. You may enter asshown in the figure.

The Documentation pane enables you to define ormodify the type, description, and help text for a maskedblock.

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Masking

Mask Editor Parameters PageThe page is used to set parameters of block insubsystem underlying the masked block.

For our mass-spring-damper, we have the followingparameters:Mass, symbol: m, editable by userDamper, c, editableSpring, k, editable

To add a variable, click addiconthen enter all thenecessary field.

add icon

delete icon

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Masking

Mask Editor Parameters Page

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Masking

Mask Initiation PageThe Initialization pane allows you to enter MATLABcommands that initialize the masked subsystem.

Simulink executes the initialization commands when it Loads the model Starts the simulation or updates the block diagram Rotates the masked block Redraws the blocks icon (if the masks icon creation

code depends on variables defined in theinitialization code)

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Masking

Mask Initiation Page

For our example, leave this page emptysince we want tomake the parameters are editable through blockparameters.

For example, if we wantour masked system hasthe following value:

m=1;c=2;k=10Type that parameters in

initialization commands.

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Masking

Mask Editor Icon PageThe Mask Editors Icon pane enables you to create icons thatcan contain descriptive text, state equations, images, andgraphics.

Commands that draw icon

Example of drawing Commands

we can use to draw the block icon.

Parameters that control icon

appearance.

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Masking

Mask Editor Icon Page

Drawing commandsThis field allows us to enter commands that draw the

blocks icon. Simulink provides a set of commands thatcan display text, one or more plots, or show a transferfunction. We may use the following commands: text,plot, displ, dpoly, etc as shown in the example

command. We must use these commands to draw youricon.

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Icon optionsThese controls allow you to specify the attributes of theblock icon.

Frame Transparency

Rotation Unit

Masking

Mask Editor Icon Page

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MaskingMasking

Mask Editor Icon PageLet draw the following figure for our masked subsystem.

Set the following icon

option:Frame: VisibleTransparency: OpaqueRotation: fixed

Unit: Normalized

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plot([0.1 0.1],[0.2 0.8])plot([0.4 0.7 0.7 0.4 0.4],[0.2 0.2 0.8 0.8 0.2])

plot([0.1 0.2],[0.4 0.4])plot([0.3 0.2 0.2 0.3],[0.3 0.3 0.5 0.5])plot([.1 .2 .2 .3 .3 .4],[.7 .7 .8 .6 .7 .7])plot([0.3 0.4],[0.4 0.4])plot([0.7 0.9],[0.5 0.5])

text(.5,.5,'m')text(.25,.35,'c')text(.25,.85,'k')text(.8,.6,'f')

MaskingMasking

Mask Editor Icon PageType the following commands into commands field

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MaskingMasking

Mask Editor Icon PageWe will get the following masked subsystem:

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MaskingMasking

Mask Editor Icon PageWe may also displaying a tif image on a block icon usingthe following drawing command:

image(imread(file_name.tif))

ki

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Close the mask editor, now, our subsystem look likeblocks of Simulink library. Double-click to see the effectof the masking.

Masking

ki

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Masking


M ki

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Masking


Di S

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Discrete System

Concept

Discrete system is dynamical system that can bedescribed using difference equation.

For example, lets consider the following system:

The process is assumed to have a sample time of 0.1sec.

)k(u)1k(x094.0)1k(xsin05.0)k(x

)1k(x1.0)1k(x)k(x

212

211

Di t S t

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Discrete System

Concept

Simulink has the ability tosimulate discrete system,

including system whosecomponents operate atdifferent rates (multi rate)and system that mix discrete

and continuous components(hybrid system).

Di t S t

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Discrete System

Lets build a model and simulate the following system:

)k(u)1k(x094.0)1k(xsin05.0)k(x

)1k(x1.0)1k(x)k(x

212

211

We may construct a Simulink model by usingprimitive blockstransfer function blockstate variable model.

The process is assumed to have a sample time of 0.1sec.

Di t S t

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Primitive Blocks

Discrete System

We can build a block diagram as the following figure:

0.094

u(k)

++ z

10.1

x2(k)

x1(k)

z

1

x2(k-1) x

1(k-1)

++

0.05sin[x1(k-1)]

-

(Sources)

(User-defined functions)

(Discrete)

(Math) (Math)

Di t S t

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Primitive Blocks

Discrete System

Therefore, we have the following Simulink model.

Next, we should define the f(u) function and sampletime.

Di t S t

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Discrete System

Double click the f(u) block, then modify the desiredfunction and sampling time. Click OK to close thewindow.

0.05*sin(u)

0.1

Primitive Blocks

Di t S t

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Discrete System

The Simulink model become as follows:

Primitive Blocks

Di t S t

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Double click the unit delayblocks, then set sample timeto 0.1.

Do the same process forother blocks: sum, gain andsource.

Discrete System

Primitive Blocks

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Discrete System

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Discrete System

Lets build a model and simulate the following system:

)k(u)1k(x094.0)1k(xsin05.0)k(x

)1k(x1.0)1k(x)k(x

212

211

In z-domain,

)z(U)z(Xsin05.0094.0z

z)z(X

)z(X1z

1.0

)z(X

12

21

Transfer Function

Discrete System

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Discrete System

Then we can construct the following block diagram:

We can make the discrete model easily based on thisblock.

(Math)(Discrete)

(Sources)

(Sinks)(User-defined functions)

F(X1)

U(z) X2(z)

+- 094.0zz

X1(z)1zz1.0

Transfer Function

Discrete System

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Discrete System

Therefore, we have the following Simulink model.

Next, we should define the f(u) function and sampletime.

Transfer Function

Discrete System

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Discrete System

Double click the f(u) block, then modify the desiredfunction and sampling time. Click OK to close thewindow.

0.05*sin(u)

0.1

Transfer Function

Discrete System

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Discrete System


Transfer Function

Discrete System

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Discrete System

Double click the discretetransfer functions, thenmodify the transfer functionparameters and sample time.

[1 0]

[1 -0.094]

0.1

[0.1 0]

[1 1]

0.1

Transfer Function

Discrete System

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Discrete System


Transfer Function

Discrete System

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Discrete System

Before we run the Simulink model, we should carefullydetermine the step size of the simulation parameterespecially when we use fix step.

In general, we can select the step size at integer ofmultiples of the shortest systems sample time.

In our example, the sample time is 0.1 so we canselect 0.1 as step size. Then we can simulate themodel.

Transfer Function

Discrete System

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Discrete System

Simulink also has capability to handel discrete systemswith involve subsystems that operate at different.

The Simulink sample-time color capability provides help

in keeping track of sample tiems.

To activates the feature, select Format:Port/SignalsDisplayand then check Sample time colors.

Multirate Discrete Time

Discrete System

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Discrete System

Hybrid System

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Hybrid System

Mixed continuous and discrete systems are composedof both sampled and continuous blocks. Such systemscan be simulated using any of the integration

methods, although certain methods are more efficientand accurate than others.

For most mixed continuous and discrete systems, theRunge-Kutta variable-step methods, ode23 and ode45,are superior to the other methods in terms of efficiencyand accuracy.

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End of Session 2

Further ReadingUsing Simulink

Documents

Simulink-02-01.ppt