MATLAB Tutorials
Session VII
Introduction to SIMULINK
Rajeev Madazhy
Email: rmadaz1@lsu.edu
Dept of Mechanical Engineering
LSU
Department of Mechanical Engineering, LSU
Session VII
Last Session….
Engineering Applications using MATLAB….
 Solving non linear differential equations
 Algorithm analysis for four bar linkage problem
 Other mechanical problems
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Session VII
Session VII Outline….
 Introduction to Simulink
 Solving simple problems using Simulink
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Session VII
Simulink…..
 Simulink is a program that runs as a companion to MATLAB
 Simulink provides a graphical user interface (GUI) that is used
in building block diagrams, performing simulations, as well as
analyzing results of dynamic systems.
 In Simulink, models are hierarchical so that you can view a
system at a high level, then double click on blocks by using
the mouse to go down through the design levels.
Department of Mechanical Engineering, LSU
Session VII
Getting started…..
Lets get started with a simple example of simulating a sin wave.
To open Simulink open the MATLAB command window first.
Click on the icon which is present in the toolbar in the command
window of MATLAB.
Alternatively you can also enter the command Simulink to open
the graphics library of simulink
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Session VII
Opening Simulink….
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Session VII
Simulink block library….
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Session VII
General list of libraries….
Source type blocks produce input signals.
The Sine Wave block is a source type block
Sink type blocks provide a place for output.
The scope block is a sink type block.
Linear type blocks perform a linear transformation.
The Integrator is a linear type block.
Connection type blocks are involved with forming
vector signals, the Mux block is an example.
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Session VII
Adding a block from the library…..
To open a block library, double click on the associated library icon in
the Simulink block library window. After opening the Sources library,
the Sources library window opens, as shown
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Session VII
Simulink Library Browser….
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Session VII
Adding a block from the library…..
 To add the first block to the diagram, point the mouse at the Sine
Wave block in the Sources library window and press the left button.
 Create a new model window by clicking on to the new icon at the
toolbar.
 Without releasing the left mouse button, drag the mouse to the
new model window and release the mouse button.
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Session VII
Simulink model window….
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Session VII
Pulling the selected blocks….
Pull in the following blocks
for our simulation from the
following libraries.
Block
From Library
Sine wave
sources
integrator
Linear
Mux
connections
Scope
sinks
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Session VII
Inputs and outputs….
In general the inputs to a block are on the left a > symbol points
into the block. In addition, outputs are generally on to the right, a
> symbol out of the block.
To add a connection, use the mouse to position the pointer over
the output port of the block. During this time the pointer changes
to cross hairs .
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Session VII
Cont…
The completed connection should look like this….
Adding a branch line….This is required when you have an output
which needs to be connected to two separate blocks
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Session VII
Cont…
To complete the connections, add a line from the output of the
integrator block to the input port of the mux block. When you are
done it should look similar to the following.
Labels can be added to lines to further annotate your model.
To create a signal label, double click on a line segment and
type the label at the insertion point.
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Session VII
Final model….
Save the model as
example1.mdl
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Session VII
Giving model parameters…..
The sine wave block
Double click on the sine wave block and examine the data fields.
Sine wave block parameters:
Amplitude
=
1
Frequency (rad/sec)
=
0.25*2*pi
Phase(rad)
=
0
Sample time
=
0
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Session VII
Block Parameters of Sine Wave….
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Session VII
Integrator Block….
Integrator block parameters:
External reset
=
None
Initial Conditions
=
0
Limit Output
=
Not checked
Show saturation point
=
Not checked
Show state port
=
Not checked
Absolute tolerance
=
auto
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Session VII
Block parameters: Integrator
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Session VII
Simulation parameters….
Go to simulation => parameters in the model window toolbar
Enter the following
values
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Session VII
Run the simulation….
To view the results of the simulation, double click on the scope block.
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Session VII
Cont….
To better fit the display in the scope window, click on the ‘Fit View’
button
. The scope window should similar to the following.
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Session VII
Example 2….
The next example would be to simulate the dynamics of second order
system.
d2
d
2
2
y
(
t
)

2

y
(
t
)


y
(
t
)

K

u (t )
n
n
n
2
dt
dt
Given that:
K  1;  0.5; n  4
Obtain the velocity and displacement response
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Session VII
Building the model….
The same procedure is applied as being shown in the first example.
Pull all the necessary blocks from the library browser.
The blocks required is as follows:
Blocks
Number
Integrator
2
Sum
1
Scope
3
Step I/P
1
Gain
3
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Session VII
Final Model….
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Session VII
Gain parameters- 1st Gain block
Similarly give the gains for the second and the third one as
shown in the model window.
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Session VII
Block parameters - Step
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Session VII
Simulation parameters….
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Session VII
Output from Scope1 and Scope2…
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Session VII
Output from Scope3….
Scope3 shows the
displacement response for the
second order system.
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Session VII
References….
MATLAB website (http://www.mathworks.com) has a comprehensive
list of examples and references to SIMULINK.
There are several books which cater to this area. One of the good
references is listed below:
Mastering Simulink 4
James B. Dabney & Thomas L. Harman
ISBN 0-13-017085-2
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Session VII
Looking back….
This completes the MATLAB Tutorial.
Sessions 1 to 7 covered almost all areas of applications of
MATLAB.
Specialized areas of MATLAB are using the toolboxes.
These are a collection of m-files that are specific to the
area of application.
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Session VII
Thank You
Department of Mechanical Engineering, LSU
Session VII