Difference between revisions of "Simulink/Tutorials/Signals"

From PrattWiki
Jump to navigation Jump to search
 
m
 
(28 intermediate revisions by the same user not shown)
Line 1: Line 1:
\section{Introduction}
+
<!-- EGR 224 specific
 
This lab focuses on introducing MATLAB and Simulink and using
 
This lab focuses on introducing MATLAB and Simulink and using
 
them to analyze transfer functions and numerically solve
 
them to analyze transfer functions and numerically solve
 
differential equations.
 
differential equations.
 
Many engineering problems can be easily modeled using block
 
Many engineering problems can be easily modeled using block
diagrams. In the Alciatore and Histand book, block diagrams are used
+
diagrams.  
 +
In the Alciatore and Histand book, block diagrams are used
 
as early as Figure 1.3 to graphically illustrate the connection of
 
as early as Figure 1.3 to graphically illustrate the connection of
 
transducers, signal processors, and recorders in measurement systems.
 
transducers, signal processors, and recorders in measurement systems.
Line 10: Line 11:
 
of control theory and how a control signal is compared with a measured
 
of control theory and how a control signal is compared with a measured
 
output to generate some error signal.
 
output to generate some error signal.
 +
-->
  
The creators of MATLAB understand that block diagrams are used to
+
The creators of [[MATLAB]] understand that block diagrams are used to
 
visually depict complicated systems, and also that
 
visually depict complicated systems, and also that
 
the mathematical characteristics of those systems, once defined, can
 
the mathematical characteristics of those systems, once defined, can
 
be used to determine the values for the various signals throughout the
 
be used to determine the values for the various signals throughout the
system.  For that reason, they developed the Simulink package as an
+
system.  For that reason, they developed the [[Simulink]] package as an
 
add-on to MATLAB.  Simulink allows you to draw your system as if you
 
add-on to MATLAB.  Simulink allows you to draw your system as if you
 
were drawing a block diagram, and then to simulate the system using a
 
were drawing a block diagram, and then to simulate the system using a
Line 27: Line 29:
 
introduction, you should be able to generate a wide variety of
 
introduction, you should be able to generate a wide variety of
 
signals, perform basic and intermediate mathematical operations,
 
signals, perform basic and intermediate mathematical operations,
visualize and save data, control models with a script, and print your model.
+
visualize and save data, control models with a script (not completed yet), and print your model.
  
\startupcn{lab9}{EGR119}
+
Note - figures are numbered by section.  I haven't figured out a better way to do this...
  
\section{Starting Simulink}
+
==Starting Simulink==
 
Simulink is an add-on package to MATLAB, and OIT has purchased several
 
Simulink is an add-on package to MATLAB, and OIT has purchased several
 
licenses for use on the Linux workstations.  To start Simulink, you
 
licenses for use on the Linux workstations.  To start Simulink, you
must first start MATLAB (by typing {\tt matlab \&}), then type {\tt
+
must first start MATLAB (by typing <code>matlab &</code>), then type <code>simulink</code>
  simulink} at the command  
+
at the command prompt within MATLAB.  At that point, the Simulink library window will come up.
prompt within MATLAB.  At that point, the Simulink library window will come up.
 
 
While you will not be creating your model in this window, you will be
 
While you will not be creating your model in this window, you will be
 
using it to obtain access to the many different built-in blocks that
 
using it to obtain access to the many different built-in blocks that
 
Simulink provides.   
 
Simulink provides.   
  
To start your own model, go to {\tt
+
To start your own model, go to <code>File->New->Model</code>.  Now you have a blank canvas to work with.   To fill it in, you need to
  File->New->Model}.  Now you have a blank canvas to work with.
 
To fill it in, you need to
 
 
know what the basic blocks are, how to bring them into your model, and
 
know what the basic blocks are, how to bring them into your model, and
 
how to connect them.
 
how to connect them.
  
\section{Basic Blocks and Connections}
+
==Basic Blocks and Connections==
The Simulink library is broken up into several categories, and each
+
[[Image:SDDemoSigGen.png|thumb|Figure 1]]
category contains several building blocks for modeling signals and
+
The Simulink library is broken up into several categories, and each category contains several building blocks for modeling signals and systems.  To look at the contents of a particular category, just double-click its name in the library window.  For example, if you double-click on the <code>Sources</code> icon, you will open a new library window containing several different ways that MATLAB can generate a signal. If you want to add one of these to your model, all you have to do is click and hold on it with the left mouse button, then drag it onto your canvas.  Try this with the <code>Signal Generator</code> block.  Your model should now have a single <code>Signal Generator</code> (fig. 1).  
systems.  To look at the contents of a particular category, just
 
double-click its name in the library window.  For example, if you
 
double-click on the {\tt Sources} icon, you will open a new library
 
window containing several different ways that MATLAB can generate a
 
signal.\footnote{Notice anything odd about the {\tt Sources} library block?}  If you want to add one of these to your model, all you have
 
to do is click and hold on it with the left mouse button, then drag it onto
 
your canvas.  Try this with the {\tt Signal Generator} block.  Your
 
model should now have a single {\tt Signal Generator}.
 
\begin{center}
 
\epsfig{file=./SIMULINK/DemoSigGen.eps}
 
\end{center}
 
  
 
To examine and change the possible parameters of a block, simply
 
To examine and change the possible parameters of a block, simply
 
double-click on it in your model window.   
 
double-click on it in your model window.   
The {\tt Signal Generator}, for example, allows
+
The <code>Signal Generator</code>, for example, allows
 
you to choose what wave form you would like, the time base to use, the
 
you to choose what wave form you would like, the time base to use, the
 
amplitude of the signal, the frequency, and what units of  
 
amplitude of the signal, the frequency, and what units of  
 
frequency to use.  If
 
frequency to use.  If
you were to want to use an input of $x(t)=\sin(8t)$, for example, you would
+
you were to want to use an input of <math>x(t)=3\sin(8t)</math>, for example, you would
choose a sine wave, using the simulation time, with an amplitude of 1
+
choose a sine wave, using the simulation time, with an amplitude of 3
 
and a frequency of 8 radians per second.  Go ahead and make those
 
and a frequency of 8 radians per second.  Go ahead and make those
changes, then click the {\tt OK} button to accept them.
+
changes, then click the <code>OK</code> button to accept them.
 +
<br clear=all>
 +
 
  
 +
[[Image:SDDemoGain.png|thumb|Figure 2]]
 
Once you have some kind of input signal, you may want to process it.
 
Once you have some kind of input signal, you may want to process it.
 
There are many different ways to process a signal in Simulink, ranging
 
There are many different ways to process a signal in Simulink, ranging
 
from basic mathematics to advanced image processing and frequency
 
from basic mathematics to advanced image processing and frequency
analysis.  For now, open up the {\tt Math Operations} category by
+
analysis.  For now, open up the <code>Math Operations</code> category by
 
double-clicking it in the original library window.  Among the
 
double-clicking it in the original library window.  Among the
different operations you can perform is the {\tt Gain} block, which
+
different operations you can perform is the <code>Gain</code> block, which
 
acts like a multiplier.  Drag a copy of this into your model, so that
 
acts like a multiplier.  Drag a copy of this into your model, so that
 
now you have a Signal Generator and a Gain block.  Move the Gain block
 
now you have a Signal Generator and a Gain block.  Move the Gain block
so it is about an inch to the right of the Signal Generator.  
+
so it is about an inch to the right of the Signal Generator (fig. 2).  
\begin{center}
+
<br clear=all>
\epsfig{file=./SIMULINK/DemoGain.eps}
 
\end{center}
 
  
 +
[[Image:SDDemoGain2.png|thumb|Figure 3]]
 
If you double-click
 
If you double-click
 
this block, you will see that it has more options than you may have
 
this block, you will see that it has more options than you may have
 
thought for a simple gain.  Generally, however, you will only need to
 
thought for a simple gain.  Generally, however, you will only need to
 
change the Gain itself.  Go ahead and set the gain to 2 and click the
 
change the Gain itself.  Go ahead and set the gain to 2 and click the
{\tt Apply} button.  Notice that the number inside the block itself
+
<code>Apply</code> button.  Notice that the number inside the block itself
changes as a result.   
+
changes as a result (fig. 3).   
\begin{center}
+
<br clear=all>
\epsfig{file=./SIMULINK/DemoGain2.eps}
 
\end{center}
 
  
 +
[[Image:SDDemoGainK.png|thumb|Figure 4]]
 +
[[Image:SDDemoGainK2.png|thumb|Figure 5]]
 
The number in the gain block will reflect the
 
The number in the gain block will reflect the
 
actual gain if there is room for it - otherwise the gain block will
 
actual gain if there is room for it - otherwise the gain block will
have the letter {\tt K} in it.  For example, if you put in 0.0001 for
+
have the letter <code>K</code> in it.  For example, if you put in 0.0001 for
the gain and hit Apply again, the block will just have a K in it.
+
the gain and hit Apply again, the block will just have a K in it (fig. 4).
\begin{center}
+
If you ''really want'' to see the gain, you can change the size of
\epsfig{file=./SIMULINK/DemoGainK.eps}
+
the block to make it large enough that the number will fit inside (fig. 5)
\end{center}
 
If you {\it really want} to see the gain, you can change the size of
 
the block to make it large enough that the number will fit inside:
 
\begin{center}
 
\epsfig{file=./SIMULINK/DemoGainK2.eps}
 
\end{center}
 
 
though generally you will not want to resize blocks just to see the
 
though generally you will not want to resize blocks just to see the
 
contents.  The main blocks you will be resizing are those with
 
contents.  The main blocks you will be resizing are those with
Line 113: Line 97:
 
larger size will make it easier to track and attach the  
 
larger size will make it easier to track and attach the  
 
different inputs.  In this case, change the gain back to 2 and hit
 
different inputs.  In this case, change the gain back to 2 and hit
{\tt OK}, then make the gain block a more normal size.
+
<code>OK</code>, then make the gain block a more normal size.
 +
<br clear=all>
  
 +
[[Image:SDDemoOuts.png|thumb|Figure 6]]
 
Finally, you will want to have some way of viewing or saving the
 
Finally, you will want to have some way of viewing or saving the
 
data.  If you go back to the original Library window and open up the
 
data.  If you go back to the original Library window and open up the
{\tt Sinks} category, you will see the various ways that MATLAB can
+
<code>Sinks</code> category, you will see the various ways that MATLAB can
 
take a signal and either send the information to the screen, to the
 
take a signal and either send the information to the screen, to the
 
workspace, or to a file.  In this case, you are going to want to both
 
workspace, or to a file.  In this case, you are going to want to both
view and manipulate the data, so drag both a {\tt Scope} and a {\tt To
+
view and manipulate the data, so drag both a <code>Scope</code> and a <code>To Workspace</code> to your model.  Put both about an inch to the right of
  Workspace} to your model.  Put both about an inch to the right of
+
the <code>Gain</code> block, with the <code>Scope</code> about an inch above and the
the {\tt Gain} block, with the {\tt Scope} about an inch above and the
+
<code>To Workspace</code> about an inch below (fig. 6).
{\tt To Workspace} about an inch below.
+
<br clear=all>
\begin{center}
 
\epsfig{file=./SIMULINK/DemoOuts.eps}
 
\end{center}
 
  
 
If you double-click the scope, an oscilloscope window will appear.
 
If you double-click the scope, an oscilloscope window will appear.
Line 132: Line 115:
 
real time.  Generally, you will add these during the construction of a
 
real time.  Generally, you will add these during the construction of a
 
model, but once you have completed the model, you will want a more
 
model, but once you have completed the model, you will want a more
permanent record of the data obtained.  This is where the {\tt To
+
permanent record of the data obtained.  This is where the <code>To Workspace</code> block comes in.
  Workspace} block comes in.
 
  
The {\tt To Workspace} block will record the signal values sent to  
+
[[Image:SDDemoOuty.png|thumb|Figure 7]]
 +
The <code>To Workspace</code> block will record the signal values sent to  
 
it as a variable in
 
it as a variable in
 
the MATLAB workspace.  If you double-click on the block, you will note
 
the MATLAB workspace.  If you double-click on the block, you will note
that you can change the variable name - go ahead and make this {\tt
+
that you can change the variable name - go ahead and make this <code> y</code>.  The <code>Save format</code> that is most readily used is <code>Array</code>,
  y}.  The {\tt Save format} that is most readily used is {\tt Array},
 
 
so go ahead  
 
so go ahead  
 
and make that change as well.  The default cases for the other
 
and make that change as well.  The default cases for the other
parameters will generally work fine.  Once done, click {\tt OK} and
+
parameters will generally work fine.  Once done, click <code>OK</code> and
 
notice that the name of the variable is now showing inside of the
 
notice that the name of the variable is now showing inside of the
block.
+
block (fig. 7).
\begin{center}
+
<br clear=all>
\epsfig{file=./SIMULINK/DemoOuty.eps}
 
\end{center}
 
  
 +
[[Image:SDDemoWire1.png|thumb|Figure 8]]
 
Now that the blocks are in place, you need to connect them.  You will
 
Now that the blocks are in place, you need to connect them.  You will
notice if you run the cursor over the small port symbol (the $>$) of a
+
notice if you run the cursor over the small port symbol (the <math>></math>) of a
 
block that the cursor changes from an arrow to crosshairs.  The way
 
block that the cursor changes from an arrow to crosshairs.  The way
 
you connect blocks is to pick the port of one block, hold down the
 
you connect blocks is to pick the port of one block, hold down the
 
left mouse button, and drag until you hit another port (or another
 
left mouse button, and drag until you hit another port (or another
wire).  Go ahead and connect the {\tt Signal Generator} to the {\tt
+
wire).  Go ahead and connect the <code>Signal Generator</code> to the <code>Gain</code> block by
  Gainblock by
+
putting the cursor on top of the output port of the <code>Signal Generator</code>,
putting the cursor on top of the output port of the {\tt Signal Generator},
 
 
holding down the left mouse button, and dragging until the cursor is
 
holding down the left mouse button, and dragging until the cursor is
over the input port of the {\tt Gain} block.  You will notice that the
+
over the input port of the <code>Gain</code> block.  You will notice that the
 
cursor changes to double crosshairs when you have found a terminus for
 
cursor changes to double crosshairs when you have found a terminus for
your wire.  Now connect the output of the {\tt Gain} block to the {\tt
+
your wire.  Now connect the output of the <code>Gain</code> block to the <code>Scope</code> (fig. 8).
  Scope}.
+
<br clear=all>
\begin{center}
 
\epsfig{file=./SIMULINK/DemoWire1.eps}
 
\end{center}
 
  
If you also want to connect the {\tt Gain} block to the {\tt To
+
If you also want to connect the <code>Gain</code> block to the  
  Workspace} block,
+
<code>To Workspace</code> block,
you will need to {\it first} click on the input of the {\tt To Workspace}
+
you will need to ''first'' click on the input of the <code>To Workspace</code>
then drag until you hit the {\it wire} connecting the scope to the
+
then drag until you hit the ''wire'' connecting the scope to the
gain block.  You cannot go back to the {\tt Gain} block's output port,  
+
gain block.  You cannot go back to the <code>Gain</code> block's output port,  
 
because every input or output port can only be used once.
 
because every input or output port can only be used once.
\pagebreak
 
  
 
Since every
 
Since every
Line 185: Line 161:
 
(thereby selecting it) and hitting delete.
 
(thereby selecting it) and hitting delete.
  
 +
[[Image:SDDemoWired.png|thumb|Figure 9]]
 
At this point, your model should have all four blocks properly wired,
 
At this point, your model should have all four blocks properly wired,
with a gain of 2 and a {\tt To Workspace} variable called $y$:
+
with a gain of 2 and a <code>To Workspace</code> variable called <math>y</math> (fig. 9).
\begin{center}
 
\epsfig{file=./SIMULINK/DemoWired.eps}
 
\end{center}
 
 
There should also be an open Scope window that came about when your
 
There should also be an open Scope window that came about when your
double-clicked the {\tt Scope} block.
+
double-clicked the <code>Scope</code> block.
 +
<br clear=all>
  
 +
==Running Simulations==
 +
[[Image:SDDemoPlotVS.png|thumb|Fig 1: Plot with no limit on maximum step size]]
 +
[[Image:SDDemoPlotVS2.png|thumb|Fig 2: Plot with limit of 0.01 on maximum step size]]
  
\section{Running Simulations}
 
 
Now that you have a basic block diagram with an input signal going
 
Now that you have a basic block diagram with an input signal going
 
through a system that multiplies that signal by 2 as well as two
 
through a system that multiplies that signal by 2 as well as two
 
different ways of examining the data, you are ready to simulate the
 
different ways of examining the data, you are ready to simulate the
system.  Within the {\tt Simulation} menu of your model,  
+
system.  Within the <code>Simulation</code> menu of your model,  
go to  {\tt Configuration
+
go to  <code>Configuration Parameters</code> and you will discover that Simulink has an extensive
  Parameters} and you will discover that Simulink has an extensive
 
 
array of options from which to choose.  For now, the critical part is
 
array of options from which to choose.  For now, the critical part is
 
telling MATLAB to store all the data and telling MATLAB the  
 
telling MATLAB to store all the data and telling MATLAB the  
 
simulation time.   
 
simulation time.   
  
Go to the {\tt Data Import/Export} selection and un-check the {\tt
+
Go to the <code>Data Import/Export</code> selection and un-check the  
  Limit data points...} option in the {\tt Save options}.  For
+
<code>Limit data points...</code> option in the <code>Save options</code>.  For
  whatever reason, MATLAB defaults on only storing the last thousand
+
whatever reason, MATLAB defaults on only storing the last thousand
  data points unless you specify otherwise.  Generally, you will want
+
data points unless you specify otherwise.  Generally, you will want
  Simulink to report all the data.
+
Simulink to report all the data.
  
With respect to timing, go to the {\tt Solver} selection.
+
With respect to timing, go to the <code>Solver</code> selection.
 
The default case - which goes from 0 to
 
The default case - which goes from 0 to
10 seconds - might work, so go ahead and hit {\tt OK}.
+
10 seconds - might work, so go ahead and hit <code>OK</code>.
Then, to run the simulation, go to {\tt Simulation} and {\tt Start}.
+
Then, to run the simulation, go to <code>Simulation</code> and <code>Start</code>.
 
The scope will show the values of the output, and when the simulation
 
The scope will show the values of the output, and when the simulation
 
is finished, MATLAB will beep.
 
is finished, MATLAB will beep.
  
If you type {\tt whos} in MATLAB, you will discover that not only did
+
If you type <code>whos</code> in MATLAB, you will discover that not only did
you generate an array called {\tt y} but that Simulink also created an
+
you generate an array called <code>y</code> but that Simulink also created an
array called {\tt tout} for you.   
+
array called <code>tout</code> for you.   
 
Now you can run the simulation and, when finished, issue the command
 
Now you can run the simulation and, when finished, issue the command
\begin{verbatim}
+
<source lang="matlab">
 
plot(tout, y)
 
plot(tout, y)
\end{verbatim}
+
</source>
 
in MATLAB's command window  
 
in MATLAB's command window  
to plot the signal.  When you do this, you will notice something very
+
to plot the signal - you should get fig. 1.   
 +
 
 +
When you do this, you will notice something very
 
disturbing - the output signal does not look like a sine wave a 8
 
disturbing - the output signal does not look like a sine wave a 8
 
radians per second.  This is because Simulink, while processing your
 
radians per second.  This is because Simulink, while processing your
Line 234: Line 212:
 
points were taken, if connected using lines, do not accurately
 
points were taken, if connected using lines, do not accurately
 
represent the signal.  
 
represent the signal.  
 
 
To forestall this, you can go
 
To forestall this, you can go
back into the {\tt Simulation} menu's {\tt Configuration Parameters} and make some
+
back into the <code>Simulation</code> menu's <code>Configuration Parameters</code> and make some
changes.  Specifically, within the {\tt Solver} selection change the
+
changes.  Specifically, within the <code>Solver</code> selection change the
{\tt Max step size} to a reasonable value
+
<code>Max step size</code> to a reasonable value
 
for the speed of the signal - perhaps 0.01.  Re-run the simulation,
 
for the speed of the signal - perhaps 0.01.  Re-run the simulation,
and re-plot your results.
+
and re-plot your results to get fig. 2.
 +
<br clear=all>
 +
 
 +
==Creating Arbitrary Inputs==
 +
[[Image:SDDemo2uc.png|thumb|Fig. 1: After deleting blocks]]
 +
[[Image:SDDemo2c.png|thumb|Fig. 2: After adding new blocks]]
 +
[[Image:SDDemo2cPlot.png|thumb|Fig. 3: Plot of new output]]
  
\section{Creating Arbitrary Inputs}
 
 
There are several ways to create different inputs signals.  The Signal
 
There are several ways to create different inputs signals.  The Signal
 
Generator is certainly the easiest way to create a basic sinusoid,
 
Generator is certainly the easiest way to create a basic sinusoid,
 
square wave, or sawtooth.  For other signals, you can use a
 
square wave, or sawtooth.  For other signals, you can use a
 
combination of sources and basic math to get what you want.  There is
 
combination of sources and basic math to get what you want.  There is
even a {\tt Signal Builder} block that can be used to draw signals.  
+
even a <code>Signal Builder</code> block that can be used to draw signals.  
 
Generally, however, the easiest way to create an input is to use a
 
Generally, however, the easiest way to create an input is to use a
{\tt Clock} block and feed it into a {\tt Fcn} block.  Go ahead and
+
<code>Clock</code> block and feed it into a <code>Fcn</code> block.  Go ahead and
save your current model as {\tt Lab2Demo1.mdl}, then do a ``save as''
+
save your current model as <code>SDDemo1.mdl</code>, then do a <code>save as</code>
and call it {\tt Lab2Demo2.mdl}.
+
and call it <code>SDDemo2.mdl</code>.
  
Now select and delete both the {\tt Signal Generator} and the {\tt
+
Now select and delete both the <code>Signal Generator</code> and the
  Gain} block.  Among other changes, you will now be left with
+
<code>Gain</code> block.  Among other changes, you will now be left with
  unconnected lines, denoted by red dotted lines:
+
unconnected lines, denoted by red dotted lines (fig 1).
\begin{center}
+
These can be deleted by selecting them and hitting delete, or they
\epsfig{file=./SIMULINK/Lab2Demo2uc.eps}
+
can be reused by putting a block's input or output ports close enough
\end{center}
+
that Simulink thinks they should be connected.  For example, drag a
These can be deleted by selecting them and hitting delete, or they
+
<code>Clock</code> block from the Sources category such that the output of
can be reused by putting a block's input or output ports close enough
+
the <code>Clock</code> is near the left-most part of the left line.  It will
that Simulink thinks they should be connected.  For example, drag a
+
attach itself to that wire, though the wire will remain red since its
{\tt Clock} block from the Sources category such that the output of
+
output end is still unconnected.
the {\tt Clock} is near the left-most part of the left line.  It will
 
attach itself to that wire, though the wire will remain red since its
 
output end is still unconnected.
 
  
Now open the {\tt User-Defined Functions} category and drag a {\tt
+
Now open the <code>User-Defined Functions</code> category and drag a  
  Fcn} block into your model, placing it in the space vacated by the
+
<code>Fcn</code> block into your model, placing it in the space vacated by the
  gain block.  The {\tt Fcn} block is larger that the {\tt Gain} block
+
gain block.  The <code>Fcn</code> block is larger that the <code>Gain</code> block
  so you can only snag one of the wires.  To get the other one, you
+
so you can only snag one of the wires.  To get the other one, you
  can drag the {\tt Fcn} block again or use the arrow keys to move
+
can drag the <code>Fcn</code> block again or use the arrow keys to move
  it until it connects and the wire turns solid black.  You should now
+
it until it connects and the wire turns solid black.  You should now
  have the following model:
+
have the model in fig 2.  
\begin{center}
 
\epsfig{file=./SIMULINK/Lab2Demo2c.eps}
 
\end{center}
 
  
To enter a function, double-click the {\tt Fcn} block.  Note that the
+
To enter a function, double-click the <code>Fcn</code> block.  Note that the
expression is currently a function of the vector {\tt u}.  This vector
+
expression is currently a function of the vector <code>u</code>.  This vector
 
represents the different inputs to the block.  Right now, we are only
 
represents the different inputs to the block.  Right now, we are only
 
using a single input - though later you can use multiplexers to send
 
using a single input - though later you can use multiplexers to send
 
multiple streams along a single line.  Your function, therefore,
 
multiple streams along a single line.  Your function, therefore,
should be written in terms of {\tt u[1]}.  For example, if you want
+
should be written in terms of <code>u[1]</code>.  For example, if you want
the output of the function to be $e^{-t/3}\cos(4t)$, then the input to
+
the output of the function to be <math>e^{-t/3}\cos(4t)</math>, then the input to
this block should be {\tt exp(-u[1]/3)*cos(4*u[1])}.  Note - Simulink
+
this block should be <code>exp(-u[1]/3)*cos(4*u[1])</code>.  Note - Simulink
does {\it not} like using the ``.*'' version of multiplication.
+
does ''not'' like using the .* version of multiplication.
  
 
Once you have that function entered, re-run the simulation.  If you
 
Once you have that function entered, re-run the simulation.  If you
make a plot of {\tt y} as a function of {\tt tout} using the command
+
make a plot of <code>y</code> as a function of <code>tout</code> using the command
{\tt plot(tout, y)}, you should get:
+
<code>plot(tout, y)</code>, you should get the plot in fig. 3.
\begin{center}
+
 
\epsfig{file=./SIMULINK/Lab2DemocPlot.eps, scale=0.4}
+
<br clear=all>
\end{center}
 
  
\section{Transferring Data}
+
==Transferring Data==
 
As mentioned earlier, you will often want to transfer data from the
 
As mentioned earlier, you will often want to transfer data from the
Simulink simulation to the workspace.  The {\tt To Workspace} block is
+
Simulink simulation to the workspace.  The <code>To Workspace</code> block is
 
the easiest way to get a signal's information to the workspace.  Just
 
the easiest way to get a signal's information to the workspace.  Just
 
make sure that the variable name is unique for each of the blocks and
 
make sure that the variable name is unique for each of the blocks and
that you have used the {\tt Array} method for storing the data.  
+
that you have used the <code>Array</code> method for storing the data.
 +
There are also <code>From Workspace</code> blocks if you want to pass in
 +
value and time data from the workspace.
  
There are also {\tt From Workspace} blocks if you want to pass in
+
==Naming and Arranging Blocks==
value and time data from the workspace.  Generally for this course,
 
you will be using the clock and the {\tt Fcn} block to generate your
 
input waveforms and will want to make sure that the output from the
 
{\tt Fcn} block is captured in a {\tt To Workspace} block.  Note that
 
the times will automatically be captured by the {\tt tout} vector.
 
 
 
\section{Naming and Arranging Blocks}
 
 
You can change the name of blocks in Simulink by double-clicking the
 
You can change the name of blocks in Simulink by double-clicking the
 
name you want to change.  This can be very useful if your blocks have
 
name you want to change.  This can be very useful if your blocks have
 
real-world analogs.  You can also probably come up with much more
 
real-world analogs.  You can also probably come up with much more
interesting names than ``To Workspace'' for your outputs.  Avoid using
+
interesting names than <code>To Workspace</code> for your outputs.  Avoid using
 
dots or slashes in the block names, however.  Stick with letters and
 
dots or slashes in the block names, however.  Stick with letters and
 
numbers if at all possible.  This will become more important in the
 
numbers if at all possible.  This will become more important in the
 
next section.
 
next section.
  
You may also occasionally want to ``aim'' a block in a different
+
You may also occasionally want to ''aim'' a block in a different
direction - to do this, simply pick the block, then go to the {\tt
+
direction - to do this, simply pick the block, then go to the  
  Format} menu and select either {\tt Flip Block} or {\tt Rotate
+
<code>Format</code> menu and select either <code>Flip Block</code> or <code>Rotate
  Block}.  You have already seen that you can resize blocks.  Take note the
+
Block</code>.  You have already seen that you can resize blocks.  Take note the
other options in the {\tt Format} menu - there may be times with
+
other options in the <code>Format</code> menu - there may be times with
 
particularly sophisticated models that you will want to use various
 
particularly sophisticated models that you will want to use various
 
colors and other options to help clarify your system.
 
colors and other options to help clarify your system.
  
\section{Running Models With Scripts}
+
==Running Models With Scripts==
Another way to run a model, besides using the {\tt Simulation} menu,
+
This section is under construction and not required for EGR 224 Spring 2010
 +
<!--
 +
Another way to run a model, besides using the <code>Simulation</code> menu,
 
is to write a script that interacts with the model.  The advantages of
 
is to write a script that interacts with the model.  The advantages of
 
using a script include the ability to set all the parameters in a
 
using a script include the ability to set all the parameters in a
Line 335: Line 307:
  
 
The key commands for using a script to interact with a model are the
 
The key commands for using a script to interact with a model are the
{\tt get\_param} and {\tt set\_param} functions.  The former reports
+
<code>get\_param</code> and <code>set\_param</code> functions.  The former reports
 
what is currently going on with a system or block while the latter
 
what is currently going on with a system or block while the latter
 
allows you to make changes to it.  For this demonstration, save the
 
allows you to make changes to it.  For this demonstration, save the
Simulink model with the {\tt Clock}, {\tt Fcn}, {\tt Scope}, and {\tt
+
Simulink model with the <code>Clock</code>, <code>Fcn</code>, <code>Scope</code>, and  
  To Workspace} blocks to a file called {\tt Lab2WithScript.mdl}.
+
<code>To Workspace</code> blocks to a file called <code>Lab2WithScript.mdl</code>.
 
Then start a new m file and add
 
Then start a new m file and add
 
\begin{lstlisting}[frame=shadowbox]
 
\begin{lstlisting}[frame=shadowbox]
Line 361: Line 333:
 
Now you have an easy way to access a particular file, and if you make
 
Now you have an easy way to access a particular file, and if you make
 
changes to the model and save it under a new name, you will only need
 
changes to the model and save it under a new name, you will only need
to change the {\tt Filename} variable to compensate.
+
to change the <code>Filename</code> variable to compensate.
  
 
To see all the simulation parameters of the system, add the following
 
To see all the simulation parameters of the system, add the following
Line 413: Line 385:
 
\end{lstlisting}
 
\end{lstlisting}
 
and when you run the script, MATLAB will report that the variable name
 
and when you run the script, MATLAB will report that the variable name
is the string {\tt y}.
+
is the string <code>y</code>.
  
 
Finally, you may want to make some changes in the code.  For example,
 
Finally, you may want to make some changes in the code.  For example,
 
if you want to see how a particular system reacts to several different
 
if you want to see how a particular system reacts to several different
inputs, you may want to change the function in the {\tt Fcn} block.
+
inputs, you may want to change the function in the <code>Fcn</code> block.
 
To see an example of this, add the following lines of code:  
 
To see an example of this, add the following lines of code:  
 
\begin{lstlisting}[frame=shadowbox]
 
\begin{lstlisting}[frame=shadowbox]
Line 433: Line 405:
 
\end{lstlisting}
 
\end{lstlisting}
  
The {\tt sim} command also has a number of optional arguments that can
+
The <code>sim</code> command also has a number of optional arguments that can
be used to reduce the number of {\tt set\_param} calls required to
+
be used to reduce the number of <code>set\_param</code> calls required to
 
prepare the simulation.  These options are generally passed through a
 
prepare the simulation.  These options are generally passed through a
function called {\tt simset} which allows you to alter several -
+
function called <code>simset</code> which allows you to alter several -
though not all - of the simulation parameters.  Type {\tt simset} in
+
though not all - of the simulation parameters.  Type <code>simset</code> in
 
the command window to get an idea of the different options that can be
 
the command window to get an idea of the different options that can be
passed through it, and type {\tt help sim} for more information about
+
passed through it, and type <code>help sim</code> for more information about
the {\tt sim} command.
+
the <code>sim</code> command.
 +
-->
  
\section{Saving and Printing Models}
+
==Saving and Printing Models==
 
To save a Simulink model, just go to the File menu and select either
 
To save a Simulink model, just go to the File menu and select either
{\tt Save} or {\tt Save As}.  Simulink models should end with {\tt
+
<code>Save</code> or <code>Save As</code>.  Simulink models should end with <code>.mdl</code>.  To print your model, you can either use the Print function
  .mdl}.  To print your model, you can either use the Print function
 
 
in the File menu or type  
 
in the File menu or type  
\begin{verbatim}
+
<source lang="matlab">
 
print -deps -sMODELNAME FILENAME.eps
 
print -deps -sMODELNAME FILENAME.eps
\end{verbatim}
+
</source>
 
The following code will not only print the model based on the
 
The following code will not only print the model based on the
filename, it will also save and close the model window when the script
+
filename, it will also save and close the model window when  
is finished:
+
<!-- the script is-->
\begin{lstlisting}[frame=single]
+
finished:
 +
<source lang="matlab">
 +
Filename = 'StringGoesHere'
 
eval(sprintf('print -s%s -deps %smodel', Filename, Filename))
 
eval(sprintf('print -s%s -deps %smodel', Filename, Filename))
 
save_system(Filename)
 
save_system(Filename)
 
close_system(Filename)
 
close_system(Filename)
\end{lstlisting}
+
</source>
 
The name of the saved picture of the model will be
 
The name of the saved picture of the model will be
{\tt{\it Filename}model.eps}.  If you are going to do several things
+
<code>'''Filename'''model.eps''</code>.  If you are going to do several things
 
with the same model, you may  
 
with the same model, you may  
want to add some kind of flag in the {\tt sprintf} command to
+
want to add some kind of flag in the <code>sprintf</code> command to
 
differentiate among plots.  For example, if you are running code in a
 
differentiate among plots.  For example, if you are running code in a
loop based on some integer counter {\tt k}, you could use the
+
loop based on some integer counter <code>k</code>, you could use the
 
following code:
 
following code:
\begin{lstlisting}[frame=single]
+
<source lang="matlab">
 
eval(sprintf('print -s%s -deps %smodel_%0.0f', Filename, Filename, k))
 
eval(sprintf('print -s%s -deps %smodel_%0.0f', Filename, Filename, k))
\end{lstlisting}
+
</source>
\pagebreak
 
 
 
 
 
\section{Assignment}
 
\subsection{Reading Help Files}
 
As part of the assignment, you need to read
 
several help files in the MATLAB Help Browser.
 
Within the Simulink Library window, go to the Help menu and select {\tt
 
  Using Simulink}.  Read the Getting Started, Simulink Basics,
 
  Creating a Model, Working with Blocks, Working with Signals, Working
 
  with Data, and Modeling with Simulink sections.  Then, again
 
within the Library window, go to the Help menu and select {\tt
 
  Blocks}.  Look at the {\tt Blocks - By Category} section and read
 
the help files - or at least the one line summaries - for
 
Continuous (Derivative, Integrator, State-space, Transfer Fcn),
 
Discontinuities (Saturation),
 
Discrete (Difference, Discrete Derivative, Discrete State-Space,
 
Discrete Transfer Fcn, Discrete-Time Integrator, Integer Delay, Unit
 
Delay), 
 
Math Operations (All of them),
 
Sinks (All of them),
 
Sources (All of them), and
 
User-Defined Functions (Fcn, MATLAB Fcn).
 
 
 
 
 
\subsection{Transfer Functions with Simulink}
 
For this assignment, you will be creating a model of a DC motor in
 
Simulink, then extending it by appliying a controller.  The first
 
block diagram you will replicate is Figure 11.3 on page 443 {\it
 
  except} do not use a Step block as an input.  Instead, use the
 
arbitary function block with the clock as described earlier in this
 
manual - that will allow you to investigate how the motor reactions to
 
several kinds of input rather than merely the step response.    Use a
 
value of 1 for the rotational intertia load (called $\E{I}{L}$ here)
 
as well as the rotational damping (called $C$ here).  Use the motor
 
from Problem 10.3 on p. 433 - that is, $\E{K}{t}=0.12$ Nm/A,
 
$\E{K}{e}=12$ V/RPM, and $\E{R}{a}$ = 1.5 $\Omega$.  Note that it
 
would be a good idea to convert the electrical constant into radians
 
per second.  Also note that this particular block diagram has the
 
Laplace transform of the angular {\it speed}, $\Bbb{\Omega}(s)$, as an
 
output - obtaining the angle would require integrating this term -
 
something MATLAB can easily due with an integrator block.
 
 
 
Once you have the block diagram completed, make a copy of the runner
 
script to take 1 s of data - this should be enough for the motor,
 
given the specific motor constants and load - to reach steady state.
 
Make a plot of the velocity as a function of time (which should
 
somewhat resemble Figure 11.4) and show the TA your graph.
 
 
 
\subsection{Control}
 
Next, you are going to add a block to represent a controller.  The
 
goal is to set a desired velocity by entering a a specific voltage and
 
then have the system simultaneously measure the desired speed of the
 
device.  The control system will then take the difference between the
 
desired and actual values and manipulate it in accordance with
 
Eqn. 11.9 on p. 444 so that a controlling voltage can be sent to the
 
motor.  Several tasks are accomplished here.  First - with feedback -
 
there is a measuring system that can determine whether the motor is
 
actually doing what it is supposed to and correct it accordingly.
 
Second, any variance caused by external factors can be accommodated.
 
Finally, the speed and general function with which the motor reaches
 
its steady state value can be altered.  In fact, using control a motor
 
that is otherwise stable could potentially be destablized if the wrong
 
kind of control is used!
 
 
 
Save the Simulink model for just the motor, then {\tt Save as...}.
 
You will be breaking the connection between the output of the
 
arbitrary function and the input of the summation.  Move the clock and
 
the arbitrary function to the left and then put in the additional
 
blocks (a summation junction and a transfer function) as represented
 
by Figure 11.6 on p. 445.  For now, the PID Controller block should
 
have a transfer function of 1 in it, representing proportional control
 
of magnitude 1.
 
 
 
 
 
 
 
\pagebreak
 
  
\section{Sample Codes and Models}
+
==Sample Codes and Models==
 +
<!--
 
\subsection{RunLab2WithScript.m\label{Sim:Runner}}
 
\subsection{RunLab2WithScript.m\label{Sim:Runner}}
 
\listinginput[1]{1}{./SIMULINK/RunLab2Demo2c.m}
 
\listinginput[1]{1}{./SIMULINK/RunLab2Demo2c.m}
Line 554: Line 452:
 
\epsfig{file=./SIMULINK/Lab2WithScriptmodel.eps}
 
\epsfig{file=./SIMULINK/Lab2WithScriptmodel.eps}
 
\end{center}
 
\end{center}
 +
-->
  
 
+
{{Protected Class Document}}
 
+
[[Category: EGR 224]]
\subsection{Generic First Derivative Model: FirstDeriv.mdl}
+
[[Category: ECE 382]]
\begin{center}
+
[[Category:ME 344]]
\epsfig{file=./SIMULINK/FirstDerivmodel.eps, angle=-90, scale=0.8}
 
\end{center}
 
 
 
\subsection{Generic Second Derivative Model: SecondDeriv.mdl}
 
\begin{center}
 
\epsfig{file=./SIMULINK/SecondDerivmodel.eps, angle=-90, scale=0.8}
 
\end{center}
 
\pagebreak
 
 
 
\subsection{Generic First Derivative Script: RunFD.m}
 
\listinginput[1]{1}{./SIMULINK/RunFD.m}
 
\pagebreak
 
 
 
\subsection{Generic Second Derivative Script: RunSD.m}
 
\listinginput[1]{1}{./SIMULINK/RunSD.m}
 
\pagebreak
 
 
 
\subsection{gzoom.m}
 
\listinginput[1]{1}{./SIMULINK/gzoom.m}
 

Latest revision as of 16:32, 19 February 2013


The creators of MATLAB understand that block diagrams are used to visually depict complicated systems, and also that the mathematical characteristics of those systems, once defined, can be used to determine the values for the various signals throughout the system. For that reason, they developed the Simulink package as an add-on to MATLAB. Simulink allows you to draw your system as if you were drawing a block diagram, and then to simulate the system using a variety of computational methods, usually with some component of integration involved.

This introduction will cover starting Simulink, understanding the basic blocks and connections, and running simulations. It will then move on to creating arbitrary functions, transferring data between the model and the workspace, and printing models. By the end of this introduction, you should be able to generate a wide variety of signals, perform basic and intermediate mathematical operations, visualize and save data, control models with a script (not completed yet), and print your model.

Note - figures are numbered by section. I haven't figured out a better way to do this...

Starting Simulink

Simulink is an add-on package to MATLAB, and OIT has purchased several licenses for use on the Linux workstations. To start Simulink, you must first start MATLAB (by typing matlab &), then type simulink at the command prompt within MATLAB. At that point, the Simulink library window will come up. While you will not be creating your model in this window, you will be using it to obtain access to the many different built-in blocks that Simulink provides.

To start your own model, go to File->New->Model. Now you have a blank canvas to work with. To fill it in, you need to know what the basic blocks are, how to bring them into your model, and how to connect them.

Basic Blocks and Connections

Figure 1

The Simulink library is broken up into several categories, and each category contains several building blocks for modeling signals and systems. To look at the contents of a particular category, just double-click its name in the library window. For example, if you double-click on the Sources icon, you will open a new library window containing several different ways that MATLAB can generate a signal. If you want to add one of these to your model, all you have to do is click and hold on it with the left mouse button, then drag it onto your canvas. Try this with the Signal Generator block. Your model should now have a single Signal Generator (fig. 1).

To examine and change the possible parameters of a block, simply double-click on it in your model window. The Signal Generator, for example, allows you to choose what wave form you would like, the time base to use, the amplitude of the signal, the frequency, and what units of frequency to use. If you were to want to use an input of \(x(t)=3\sin(8t)\), for example, you would choose a sine wave, using the simulation time, with an amplitude of 3 and a frequency of 8 radians per second. Go ahead and make those changes, then click the OK button to accept them.


Figure 2

Once you have some kind of input signal, you may want to process it. There are many different ways to process a signal in Simulink, ranging from basic mathematics to advanced image processing and frequency analysis. For now, open up the Math Operations category by double-clicking it in the original library window. Among the different operations you can perform is the Gain block, which acts like a multiplier. Drag a copy of this into your model, so that now you have a Signal Generator and a Gain block. Move the Gain block so it is about an inch to the right of the Signal Generator (fig. 2).

Figure 3

If you double-click this block, you will see that it has more options than you may have thought for a simple gain. Generally, however, you will only need to change the Gain itself. Go ahead and set the gain to 2 and click the Apply button. Notice that the number inside the block itself changes as a result (fig. 3).

Figure 4
Figure 5

The number in the gain block will reflect the actual gain if there is room for it - otherwise the gain block will have the letter K in it. For example, if you put in 0.0001 for the gain and hit Apply again, the block will just have a K in it (fig. 4). If you really want to see the gain, you can change the size of the block to make it large enough that the number will fit inside (fig. 5) though generally you will not want to resize blocks just to see the contents. The main blocks you will be resizing are those with multiple inputs or outputs, for example, summation blocks there the larger size will make it easier to track and attach the different inputs. In this case, change the gain back to 2 and hit OK, then make the gain block a more normal size.

Figure 6

Finally, you will want to have some way of viewing or saving the data. If you go back to the original Library window and open up the Sinks category, you will see the various ways that MATLAB can take a signal and either send the information to the screen, to the workspace, or to a file. In this case, you are going to want to both view and manipulate the data, so drag both a Scope and a To Workspace to your model. Put both about an inch to the right of the Gain block, with the Scope about an inch above and the To Workspace about an inch below (fig. 6).

If you double-click the scope, an oscilloscope window will appear. The scope is useful for viewing the signals throughout a simulation in real time. Generally, you will add these during the construction of a model, but once you have completed the model, you will want a more permanent record of the data obtained. This is where the To Workspace block comes in.

Figure 7

The To Workspace block will record the signal values sent to it as a variable in the MATLAB workspace. If you double-click on the block, you will note that you can change the variable name - go ahead and make this y. The Save format that is most readily used is Array, so go ahead and make that change as well. The default cases for the other parameters will generally work fine. Once done, click OK and notice that the name of the variable is now showing inside of the block (fig. 7).

Figure 8

Now that the blocks are in place, you need to connect them. You will notice if you run the cursor over the small port symbol (the \(>\)) of a block that the cursor changes from an arrow to crosshairs. The way you connect blocks is to pick the port of one block, hold down the left mouse button, and drag until you hit another port (or another wire). Go ahead and connect the Signal Generator to the Gain block by putting the cursor on top of the output port of the Signal Generator, holding down the left mouse button, and dragging until the cursor is over the input port of the Gain block. You will notice that the cursor changes to double crosshairs when you have found a terminus for your wire. Now connect the output of the Gain block to the Scope (fig. 8).

If you also want to connect the Gain block to the To Workspace block, you will need to first click on the input of the To Workspace then drag until you hit the wire connecting the scope to the gain block. You cannot go back to the Gain block's output port, because every input or output port can only be used once.

Since every wire should have at least one new port connection, you must begin from that port. Again, you will get the double crosshairs when you are over a wire such that a connection will be made and you will notice a node symbol (small black dot) at the connection. If you make a mistake and drop the wire before it is connected, you will get a dashed red wire with a port symbol at the end of it. You can remove this wire by left clicking on it (thereby selecting it) and hitting delete.

Figure 9

At this point, your model should have all four blocks properly wired, with a gain of 2 and a To Workspace variable called \(y\) (fig. 9). There should also be an open Scope window that came about when your double-clicked the Scope block.

Running Simulations

Fig 1: Plot with no limit on maximum step size
Fig 2: Plot with limit of 0.01 on maximum step size

Now that you have a basic block diagram with an input signal going through a system that multiplies that signal by 2 as well as two different ways of examining the data, you are ready to simulate the system. Within the Simulation menu of your model, go to Configuration Parameters and you will discover that Simulink has an extensive array of options from which to choose. For now, the critical part is telling MATLAB to store all the data and telling MATLAB the simulation time.

Go to the Data Import/Export selection and un-check the Limit data points... option in the Save options. For whatever reason, MATLAB defaults on only storing the last thousand data points unless you specify otherwise. Generally, you will want Simulink to report all the data.

With respect to timing, go to the Solver selection. The default case - which goes from 0 to 10 seconds - might work, so go ahead and hit OK. Then, to run the simulation, go to Simulation and Start. The scope will show the values of the output, and when the simulation is finished, MATLAB will beep.

If you type whos in MATLAB, you will discover that not only did you generate an array called y but that Simulink also created an array called tout for you. Now you can run the simulation and, when finished, issue the command

plot(tout, y)

in MATLAB's command window to plot the signal - you should get fig. 1.

When you do this, you will notice something very disturbing - the output signal does not look like a sine wave a 8 radians per second. This is because Simulink, while processing your model, tries to solve as quickly as possible by taking as large a time step as possible. For this particular model, allowing it to do that has produces a somewhat disastrous result - the locations at which data points were taken, if connected using lines, do not accurately represent the signal. To forestall this, you can go back into the Simulation menu's Configuration Parameters and make some changes. Specifically, within the Solver selection change the Max step size to a reasonable value for the speed of the signal - perhaps 0.01. Re-run the simulation, and re-plot your results to get fig. 2.

Creating Arbitrary Inputs

Fig. 1: After deleting blocks
Fig. 2: After adding new blocks
Fig. 3: Plot of new output

There are several ways to create different inputs signals. The Signal Generator is certainly the easiest way to create a basic sinusoid, square wave, or sawtooth. For other signals, you can use a combination of sources and basic math to get what you want. There is even a Signal Builder block that can be used to draw signals. Generally, however, the easiest way to create an input is to use a Clock block and feed it into a Fcn block. Go ahead and save your current model as SDDemo1.mdl, then do a save as and call it SDDemo2.mdl.

Now select and delete both the Signal Generator and the Gain block. Among other changes, you will now be left with unconnected lines, denoted by red dotted lines (fig 1). These can be deleted by selecting them and hitting delete, or they can be reused by putting a block's input or output ports close enough that Simulink thinks they should be connected. For example, drag a Clock block from the Sources category such that the output of the Clock is near the left-most part of the left line. It will attach itself to that wire, though the wire will remain red since its output end is still unconnected.

Now open the User-Defined Functions category and drag a Fcn block into your model, placing it in the space vacated by the gain block. The Fcn block is larger that the Gain block so you can only snag one of the wires. To get the other one, you can drag the Fcn block again or use the arrow keys to move it until it connects and the wire turns solid black. You should now have the model in fig 2.

To enter a function, double-click the Fcn block. Note that the expression is currently a function of the vector u. This vector represents the different inputs to the block. Right now, we are only using a single input - though later you can use multiplexers to send multiple streams along a single line. Your function, therefore, should be written in terms of u[1]. For example, if you want the output of the function to be \(e^{-t/3}\cos(4t)\), then the input to this block should be exp(-u[1]/3)*cos(4*u[1]). Note - Simulink does not like using the .* version of multiplication.

Once you have that function entered, re-run the simulation. If you make a plot of y as a function of tout using the command plot(tout, y), you should get the plot in fig. 3.


Transferring Data

As mentioned earlier, you will often want to transfer data from the Simulink simulation to the workspace. The To Workspace block is the easiest way to get a signal's information to the workspace. Just make sure that the variable name is unique for each of the blocks and that you have used the Array method for storing the data. There are also From Workspace blocks if you want to pass in value and time data from the workspace.

Naming and Arranging Blocks

You can change the name of blocks in Simulink by double-clicking the name you want to change. This can be very useful if your blocks have real-world analogs. You can also probably come up with much more interesting names than To Workspace for your outputs. Avoid using dots or slashes in the block names, however. Stick with letters and numbers if at all possible. This will become more important in the next section.

You may also occasionally want to aim a block in a different direction - to do this, simply pick the block, then go to the Format menu and select either Flip Block or Rotate Block. You have already seen that you can resize blocks. Take note the other options in the Format menu - there may be times with particularly sophisticated models that you will want to use various colors and other options to help clarify your system.

Running Models With Scripts

This section is under construction and not required for EGR 224 Spring 2010

Saving and Printing Models

To save a Simulink model, just go to the File menu and select either Save or Save As. Simulink models should end with .mdl. To print your model, you can either use the Print function in the File menu or type

print -deps -sMODELNAME FILENAME.eps

The following code will not only print the model based on the filename, it will also save and close the model window when finished:

Filename = 'StringGoesHere'
eval(sprintf('print -s%s -deps %smodel', Filename, Filename))
save_system(Filename)
close_system(Filename)

The name of the saved picture of the model will be Filenamemodel.eps. If you are going to do several things with the same model, you may want to add some kind of flag in the sprintf command to differentiate among plots. For example, if you are running code in a loop based on some integer counter k, you could use the following code:

eval(sprintf('print -s%s -deps %smodel_%0.0f', Filename, Filename, k))

Sample Codes and Models

Class Document Protection