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Linear Analysis Tool

Linearize Simulink models

Description

The Linear Analysis Tool lets you perform linear analysis of nonlinear Simulink® models.

Using this tool you can:

  • Interactively linearize models at different operating points

  • Interactively obtain operating points by trimming or simulating models

  • Perform exact linearization of nonlinear models

  • Perform frequency response estimation of nonlinear models

  • Batch linearize models for varying parameter values

  • Generate MATLAB® code for performing linearization tasks

  • Generate MATLAB code for computing operating points

Open the Linear Analysis Tool App

  • Simulink model editor: Select Analysis > Control Design > Linear Analysis.

  • Simulink model editor: Select Analysis > Control Design > Frequency Response Estimation.

  • Simulink model editor: Right-click a block, and select Linear Analysis > Linearize Block.

Parameters

expand all

Linear Analysis Tab

Linearization inputs, outputs, and loop openings. The currently active I/O set is displayed. To change the I/O set, select one of the following:

  • Model I/Os — Use the inputs, outputs, and loop openings specified in the Simulink model. For more information on specifying analysis points in your model, see Specify Portion of Model to Linearize in Simulink Model.

  • Root Level Inports and Outports — Use the root level inputs and outputs of the Simulink model.

  • Linearize the Currently Selected Block — Use the input and output ports of the currently selected block in the Simulink model.

  • Create New Linearization I/Os — Specify inputs, outputs, and loop openings. For more information, see Specify Portion of Model to Linearize in Linear Analysis Tool.

  • Existing I/Os — Select a previously created I/O set.

  • View/Edit — View or edit the currently selected operating point. For more information, see Edit Analysis Points.

Linearization operating point. The current operating point is displayed. To change the operating point, select one of the following:

  • Model Initial Condition — Use the initial conditions defined in the Simulink.

  • Linearize At — Simulate the model using the model initial conditions, and use the simulation snapshot at the specified time as the operating point. For more information, see Linearize at Simulation Snapshot.

  • Linearize at Multiple Points — Select multiple previously created operating points.

  • Existing Operating points — Select a previously created operating point.

  • Trim Model — Compute a steady-state operating point. For more information, see Compute Steady-State Operating Points.

  • Take Simulation Snapshot — Simulate the model using the model initial conditions, and compute an operating point at the specified simulation snapshot times. For more information, see Find Operating Points at Simulation Snapshots.

  • View/Edit — View or edit the currently selected operating point.

To vary parameters for batch linearization, in the drop-down list, click Select parameters to vary. On the Parameter Variations tab, specify the parameters to vary.

For more information, see Specify Parameter Samples for Batch Linearization.

Select to display result details after linearization. For more information, see View Linearized Model Equations Using Linear Analysis Tool.

Select to collect diagnostic information during linearization and open an Advisor tab for interactive troubleshooting of linearization problems. For more information, see Troubleshoot Linearization Results in Linear Analysis Tool.

Note

The Linear Analysis Tool only collects diagnostic information when Linearization Advisor is checked before performing a linearization task.

Estimation Tab

Estimation input signal. The current input signal is displayed. To change the input signal, select one of the following:

  • Sinestream — Create an input signal that consists of adjacent sine waves of varying frequencies. For more information, see Sinestream Input Signals.

  • Fixed Sample Time Sinestream — Create a discrete-time sinestream input with a specified sample time.

  • Chirp — Create a swept-frequency cosine input signal. For more information, see Chirp Input Signals.

  • Random — Create a random input signal.

Linearization inputs, outputs, and loop openings. The currently active I/O set is displayed. To change the I/O set, select one of the following:

  • Model I/Os — Use the inputs, outputs, and loop openings specified in the Simulink model. For more information on specifying analysis points in your model, see Specify Portion of Model to Linearize in Simulink Model.

  • Root Level Inports and Outports — Use the root level inputs and outputs of the Simulink model.

  • Linearize the Currently Selected Block — Use the input and output ports of the currently selected block in the Simulink model.

  • Create New Linearization I/Os — Specify inputs, outputs, and loop openings. For more information, see Specify Portion of Model to Linearize in Linear Analysis Tool.

  • Existing I/Os — Select a previously created I/O set.

  • View/Edit — View or edit the currently selected operating point. For more information, see Edit Analysis Points.

Linearization operating point. The current operating point is displayed. To change the operating point, select one of the following:

  • Model Initial Condition — Use the initial conditions defined in the Simulink.

  • Linearize At — Simulate the model using the model initial conditions, and use the simulation snapshot at the specified time as the operating point. For more information, see Linearize at Simulation Snapshot.

  • Linearize at Multiple Points — Select multiple previously created operating points.

  • Existing Operating points — Select a previously created operating point.

  • Trim Model — Compute a steady-state operating point. For more information, see Compute Steady-State Operating Points.

  • Take Simulation Snapshot — Simulate the model using the model initial conditions, and compute an operating point at the specified simulation snapshot times. For more information, see Find Operating Points at Simulation Snapshots.

  • View/Edit — View or edit the currently selected operating point.

Select to display result details about the estimation configuration and input signal used for estimation.

Select to collect diagnostic information that displays after estimation. You can use the diagnostic information to analyze the estimation result and troubleshoot estimation problems. For more information, see Analyze Estimated Frequency Response.

Note

The Linear Analysis Tool only collects diagnostic information when Diagnostic Viewer is selected before performing an estimation task.

Introduced in R2011b