1. ECEN/MAE 3723 – Systems I
MATLAB Lecture 2

2. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

3. What is Simulink? (1)
A software package for modeling, simulating, and analyzing dynamic systems.
Supports linear and nonlinear systems, modeled in continuous time, sample time, or a hybrid of the two.
Systems can also be multirate (i.e. different parts that are sampled or updated at different rates)

4. What is Simulink? (2)
For modeling, it provides a graphical user interface (GUI) for building models as block diagrams (using click-and-drag mouse operations)
Can build models in hierarchical fashion (using both top-down and bottom-up approaches)
You can simulate, analyze the output results, explore, revise your models and have FUN!

5. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

6. Start a Simulink Session
Type simulink
on Matlab command window
Click on the SIMULINK icon on toolbar

7. Simulink Library Browser
SEARCH window
CREAT NEW MODEL icon
BLOCK set
for model construction
LIBRARY

8. Create a New Model CREAT NEW MODEL icon Workspace where you
construct your model

9. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

10. Building a Model
Simulink Block Diagram – pictorial model of a dynamic system
Each block represents an elementary dynamic system that produces an output (either continuous or discrete output)
Lines represent connections of block inputs to block outputs u
(Input) x
(states) y
(Output)

11. Building a Model (2)
The following steps will guide you to construct a system/model:
STEP 1: Creating Blocks
STEP 2: Making connections
STEP 3: Set Parameters
STEP 4: Running Simulation

12. from the Sources library
Building a Model (3)
Step 1: Creating Blocks
Click-Drag-Drop the Sine Wave block to Workspace Window
This is the
Sine Wave block is
from the Sources library
Sources library
Save this model

13. the Signals &Systems library
Building a Model (4)
Step 1: Creating Blocks
These are
from the Sinks library
The Gain block is
from the Math library
The Mux block is from
the Signals &Systems library

14. Building a Model (5) Step 2: Making connections
To make connection: left-click while holding down control key (on keyboard) and drag from source port to a destination port
A connected Model

15. Building a Model (6) Step 3: Set Parameters
Gain value = 5
Name the output parameter as “out1”
Double click the Gain block to set the parameter for the Gain block

16. Building a Model (7) Step 4: Running Simulation
click “simulation parameters” to set up the desired parameters
You can change the “stop time” and
then click the “OK button”
Click here to run the simulation

17. Building a Model (8) View output via Scope block Output of the scope
Double click on Scope block to display output of the scope
Note: Scope block is similar to oscilloscope!
Output of the scope
Yellow: Input sine wave
Purple: Output (sine wave with gain of 5
To fit graph to frame

18. Building a Model (9) View output (workspace)
You can plot the output using the plot function
View output (workspace)
Three outputs show here

19. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

20. Example 1:Differential Equations (1)
Example of a dynamic system: A mass-spring-damper system M K B x
The Mathematical model of the system is describe by:
Lets M=2kg; B = 2 Ns/m; K=2 N/m

21. Example 1:Differential Equations (2)
Use Simulink to simulate the step response of the system, i.e.
STEP 1: Creating Blocks
Unit Step Input
f(t), N 1
Time, s
Select BLOCK set
Location in Simulink Library
Step
Sources
Sum
Math Operation
Gain
Integrator
Continuous
Scope & To Workspace
Sinks

22. Example 1:Differential Equations (2)
STEP 2: Making connections

23. Example 1:Differential Equations (3)
STEP 3: Set Parameters
Set Step time =0
Note: Assume all initial conditions = 0

24. Example 1:Differential Equations (4)
STEP 4: Running Simulation
Open “simulation parameters” window
Set “Stop time” = 30 1 2
RUN
Simulation

25. Example 1:Differential Equations (5)
Step Response for the mass-spring-damper system example
Output from Scope block
Plot system response

26. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

27. Example 2: Transfer Function (1)
Use the same mass-spring-damper system example and simulate the response using transfer function approach
The transfer function of the equation
(assume all initial conditions =0)

28. Example 2: Transfer Function (2)
STEP 1: Creating Blocks
Select BLOCK set
Location in Simulink Library
Step
Sources
Transfer Function
Continuous
Scope & To Workspace
Sinks

29. Example 2: Transfer Function (3)
STEP 2: Making connections

30. Example 2: Transfer Function (4)
STEP 3: Set Parameters
Set Step time =0

31. Example 2: Transfer Function (5)
STEP 4: Running Simulation
Open “simulation parameters” window
Set “Stop time” = 30 1 2
RUN
Simulation

32. Example 2: Transfer Function (6)
Same output as before (Slide 21)
Output from Scope block
Plot system response

33. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

34. Creating Subsystems (1)
Subsystem – similar to “Subroutine”
Advantage of Subsystems:
Reduce the number of blocks display on the main window (i.e. simplify the model)
Group related blocks together (i.e. More organized)
Can create a hierarchical block diagram (i.e. you can create subsystems within a subsystem )
Easy to check for mistakes and to explore different parameters

35. Creating Subsystems (2)
Create Subsystem using model in Example 1
STEP 1: Creating Blocks (Main window)
This is the Subsystem block is
from the Subsystems library

36. Creating Subsystems (3)
STEP 2: Double click Subsystem block and create a model in the Subsystem block
Inport
(named from “sum”
Outport
(three outports)

37. Creating Subsystems (4)
STEP 3: Making connections (Main window)

38. Creating Subsystems (5)
STEP 4: Set Parameter (Main window)
STEP 5: Running Simulation
Then view output response
Output from Scope block

39. Lecture Overview What is Simulink? How to use Simulink
Getting Start with Simulink
Building a model
Example 1 (Differential Equations )
Example 2 (Transfer Function)
Creating Subsystems
Useful Information

40. Useful Information (1) Ramp Function Set Slope
Set Start time for Ramp function
Set initial value

41. Useful Information (2) Unit Step Function or Impulse Input(t) 5 t(s)
Input(t)
Unit Step Function or Impulse
Start at 0 s
Start at 5.01 s

42. Useful Information (3)
To run programs, have to be in the current active directory or in a directory in the path (goto File  Set path... )
To copy the SIMULINK Model from Simulink Workspace and add to report (Edit  Copy model to clipboard)
Need help on SIMULINK (At Simulink Library Browser  Click Help)