An Introduction to Simulink

1
An Introduction to Simulink

• Marios S. Pattichis

2
Configuration Parameters

• Simulink is designed to be a front-end tool for
• integrating ordinary differential equations
• (ODEs). So, you need to keep sampling
• issues in mind
• Experiment with the ODE Solver parameters to
  make things appear correctly.

3
Setting the Configuration Parameters

• To start
• 1. Click on the Simulink icon to open up
• Simulink in Matlab.
• 2. In the new model window, click on the
• configuration parameters.

4
Starting and Ending Time Parameters

• Simulation time
• Start time 0.0 End time 100
• Note that these times come from the Sources
• parameters. Keep in mind that the Sources are
• usually designed for continuous-time (not
  discrete
• time) simulations.

5
Solver Configuration Parameters

• Solver Options
• Type Variable-step
• Solver discrete (no continuous-states)
• Max Step Size 0.5 lt- Set lower for better
  simulations!
• Or
• Type Fixed-step
• Solver discrete (no continuous-states)
• Fixed Step Size (fundamental sample size)
  0.5
• Set lower Fixed Step Size for better
  simulations!
• The rest are not as important

6
Connecting Things

• 1. Hold down the Control key down.
• 2. Click on the source icon.
• 3. Click on the sink icon.
• 4. Press the left mouse key to make the
• connection.

7
Displaying Things

• Can use the scope attached to any signal.
• Use the Autoscale function that appears as
  binoculars in order to look at the results of the
  entire simulations
• Click on the X, the Y or the zoom functions
  to look at any specific part of the simulation

8
Documenting Your Work

• Use Alt PrntScrn to capture a window of
  your work
• Then, in Word, simple use Paste to get the
  window of your simulation

9
A Simple Example Displaying a Chirp Signal in
Simulink
The Model -gt
10
Chirp Parameters
Thus, the correct display should show a slowly
varying sinusoid that is speeding up. From the
source parameters Start time 0 End time
100
11
Configuration Parameters
Notice the Fixed-step size of 0.1.
12
After Running the Simulation
After clicking on Autoscale, it all appears to
be working.
13
Aliasing Due to Insufficient Sampling
After changing the Fixed-step size to 1 ...
TOO LARGE!