Bode Response of Simulink Model

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Contents

Index

• Getting Started

Product Overview

• Steady-State Operating Points

• Linearization

Applications of Linearization

Open-Loop Response of Control System for Stability Margin Analysis

Bode Response of Simulink Model

watertank Simulink Model

• PID Control Design

About This Tutorial

PID Control Design Using Robust-Response-Time Tuning Algorithm

PID Control Design Using Bode Graphical Tuning

Closed-Loop Simulation of Simulink Model

• User's Guide

• Blocks

• Functions

Examples

• Release Notes

This example shows how to use the Linear Analysis Tool to linearize a model at the operating point specified in the model. The model operating point consists of the model initial state values and input signals.

Code Alternative

Open Simulink model.
```
sys = 'watertank';
open_system(sys)
```
The Water-Tank System block represents the plant in this control system and includes all of the system nonlinearities.
In the Simulink model window, select Tools > Control Design > Linear Analysis.
This action opens the Linear Analysis Tool for the model.
In the Simulink model window, define the portion of the model to linearize:
- Right-click the PID Controller block output signal, which is the input to the plant. Select Linearization Points > Input Point.
- Right-click the Water-Tank System output signal, and select Linearization Points > Output Point.
The linearization I/O markers appear in the model.
Right-click the Water-Tank System output signal and select Linearization Points > Open Loop.
This command removes the effects of the feedback signal on the linearization without changing the model operating point. The loop opening marker appears in the model.

In the Exact Linearization tab of the Linear Analysis Tool, click for the Analysis I/Os list to see the model linearization input and output points.
Click for the Operating Point list to see the selected operating point. By default, the model initial condition is selected as the operating point.
This action launches the Model Initial Condition Viewer.
In the Plot linear result in a list, select Bode response plot.
Click to linearize the model.
The Bode plot of the linearized system appears.

This Bode plot looks like a stable first-order response, as expected.
Close Simulink model.
```
bdclose(sys);
```