ECENMAE 3723 Systems I

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ECEN/MAE 3723 Systems I

• MATLAB Lecture 2

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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

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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)

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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!

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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

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Start a Simulink Session
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Simulink Library Browser
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Create a New Model
CREAT NEW MODEL icon
Workspace where you construct your model
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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

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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

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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

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Building a Model (3)

• Step 1 Creating Blocks

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Building a Model (4)

• Step 1 Creating Blocks

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Building a Model (5)

• Step 2 Making connections

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Building a Model (6)

• Step 3 Set Parameters

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Building a Model (7)

• Step 4 Running Simulation

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Building a Model (8)

• View output via Scope block

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Building a Model (9)

• View output (workspace)

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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

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Example 1Differential Equations (1)

• Example of a dynamic system A mass-spring-damper
  system

The Mathematical model of the system is describe
by
Lets M2kg B 2 Ns/m K2 N/m
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Example 1Differential Equations (2)

• Use Simulink to simulate the step response of the
  system, i.e.
• STEP 1 Creating Blocks

Unit Step Input
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Example 1Differential Equations (2)

STEP 2 Making connections
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Example 1Differential Equations (3)

STEP 3 Set Parameters
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Example 1Differential Equations (4)
STEP 4 Running Simulation
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Example 1Differential Equations (5)
Step Response for the mass-spring-damper system
example
Output from Scope block
Plot system response
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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

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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)
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Example 2 Transfer Function (2)

• STEP 1 Creating Blocks

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Example 2 Transfer Function (3)

• STEP 2 Making connections

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Example 2 Transfer Function (4)

• STEP 3 Set Parameters

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Example 2 Transfer Function (5)

• STEP 4 Running Simulation

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Example 2 Transfer Function (6)

• Same output as before (Slide 21)

Output from Scope block
Plot system response
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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

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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

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Creating Subsystems (2)
Create Subsystem using model in Example 1 STEP 1
Creating Blocks (Main window)
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Creating Subsystems (3)
STEP 2 Double click Subsystem block and create a
model in the Subsystem block
Inport (named from sum
Outport (three outports)
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Creating Subsystems (4)
STEP 3 Making connections (Main window)
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Creating Subsystems (5)
STEP 4 Set Parameter (Main window) STEP 5
Running Simulation Then view output response
Output from Scope block
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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

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Useful Information (1)

• Ramp Function

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Useful Information (2)

• Unit Step Function or Impulse

Start at 0 s
Start at 5.01 s
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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)