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R2012a Documentation → Simulink Control Design
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Contents

Index

• Getting Started

Key Features

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

• Operating Points

• Linear Analysis Plots

• Model Verification

Check Bode Characteristics

Check Gain and Phase Margins

Check Linear Step Response Characteristics

Check Nichols Characteristics

Check Pole-Zero Characteristics

Check Singular Value Characteristics

• Functions

Examples

• Release Notes

Check Gain and Phase Margins - Check that gain and phase margin bounds are satisfied during simulation

Library

Simulink Control Design

Description

This block is same as the Gain and Phase Margin Plot block except for different default parameter settings in the Bounds tab.

Check that bounds on gain and phase margins of a linear system, computed from a nonlinear Simulink model, are satisfied during simulation.

The Simulink model can be continuous-time, discrete-time or multirate and can have time delays. Because you can specify only one linearization input/output pair in this block, the linear system is Single-Input Single-Output (SISO).

During simulation, the software linearizes the portion of the model between specified linearization inputs and outputs, computes the gain and phase margins, and checks that the gain and phase margins satisfy the specified bounds.

If all bounds are satisfied, the block does nothing.
If a bound is not satisfied, the block asserts, and a warning message appears at the MATLAB prompt. You can also specify that the block:
- Evaluate a MATLAB expression.
- Stop the simulation and bring that block into focus.

During simulation, the block can also output a logical assertion signal:

If all bounds are satisfied, the signal is true (1).
If a bound is not satisfied, the signal is false (0).

You can add multiple Check Gain and Phase Margins blocks in your model to check gain and phase margin bounds on various portions of the model.

You can also plot the gain and phase margins on a Bode, Nichols or Nyquist plot or view the margins in a table and verify that the gain and phase margins satisfy the bounds.

This block and the other Model Verification blocks test that the linearized behavior of a nonlinear Simulink model is within specified bounds during simulation.

When a model does not violate any bound, you can disable the block by clearing the assertion option. If you modify the model, you can re-enable assertion to ensure that your changes do not cause the model to violate a bound.
When a model violates any bound, you can use Simulink Design Optimization software to optimize the linear system to meet the specified requirements in this block.

You can save the linear system as a variable in the MATLAB workspace.

The block does not support code generation and can be used only in Normal simulation mode.

Parameters

The following table summarizes the Gain and Phase Margin Plot block parameters, accessible via the block parameter dialog box. For more information, see Parameters in the Gain and Phase Margin Plot block reference page.

Task		Parameters
Configure linearization.	Specify inputs and outputs (I/Os).	In Linearizations tab: Linearization inputs/outputs Click a model signal to add it as a linearization I/O
	Specify settings.	In Linearizations tab: Linearize on Snapshot times Trigger type
	Specify algorithm options.	In Linearizations tab: Enable zero-crossing detection Use exact delays Linear system sample time Sample time rate conversion method Prewarp frequency (rad/s)
	Specify labels for linear system I/Os and state names.	In Linearizations tab: Use full block names Use bus signal names
Specify bounds on gain and phase margins of the linear system for assertion.		Include gain and phase margins in assertion in Bounds tab.
Specify assertion options (only when you specify bounds on the linear system).		In Assertion tab: Enable assertion Simulation callback when assertion fails (optional) Stop simulation when assertion fails Output assertion signal
Save linear system to MATLAB workspace.		Save data to workspace in Logging tab.
View bounds violations graphically in a plot window.		Show Plot
Display plot window instead of block parameters dialog box on double-clicking the block.		Show plot on block open