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loopview

Graphically analyze results of control system tuning using slTuner interface

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Syntax

loopview(st,controls,measurements)
loopview(st,info)

Description

loopview(st,controls,measurements) plots characteristics of the control system described by the slTuner interface st. Use loopview to analyze the performance of a tuned control system you obtain using looptune.

loopview plots:

  • The gains of the open-loop frequency response measured at the plant inputs (controls analysis points) and at plant outputs (measurements analysis points)

  • The (largest) gain of the sensitivity and complementary sensitivity functions at the plant inputs or outputs

example

loopview(st,info) uses the info structure returned by looptune and also plots the target and tuned values of tuning constraints imposed on the system. Use this syntax to assist in troubleshooting when tuning fails to meet all requirements.

Additional plots with this syntax include:

  • Normalized multi-loop disk margins at the plant inputs and outputs. For more information about disk margins, see Stability Analysis Using Disk Margins (Robust Control Toolbox).

  • Target vs. achieved response for any additional tuning goal you used with looptune.

example

Examples

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Open Script

Tune the Simulink® model, rct_engine_speed, to achieve a specified settling time. Use loopview to graphically analyze the tuning results.

Open the model.

mdl = 'rct_engine_speed';
open_system(mdl);

Create an slTuner interface for the model and specify the PID Controller block to be tuned.

st0 = slTuner(mdl,'PID Controller');

Specify a requirement to achieve a 2 second settling time for the Speed signal when tracking the reference signal.

req = TuningGoal.Tracking('Ref','Speed',2);

Tune the PID Controller block.

addPoint(st0,'u')

control = 'u';
measurement = 'Speed';

wc = 1;

[st1,gam,info] = looptune(st0,control,measurement,wc);

Final: Peak gain = 0.979, Iterations = 4
Achieved target gain value TargetGain=1.

View the response of the model for the tuned block values.

loopview(st1,control,measurement);

Compare the performance of the tuned block against the tuning goals.

figure
loopview(st1,info);

Input Arguments

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Interface for tuning control systems modeled in Simulink, specified as an slTuner interface.

Controller output name, specified as one of the following:

  • Character vector — Name of an analysis point of st.

    You can specify the full name or any portion of the name that uniquely identifies the analysis point among the other analysis points of st.

    For example, 'u'.

  • Cell array of character vectors — Multiple analysis point names.

    For example, {'u','y'}.

Measurement signal name, specified as one of the following:

  • Character vector — Name of an analysis point of st.

    You can specify the full name or any portion of the name that uniquely identifies the analysis point among the other analysis points of st.

    For example, 'u'.

  • Cell array of character vector — Multiple analysis point names.

    For example, {'u','y'}.

Detailed information about each optimization run, specified as the structure returned by looptune.

Alternative Functionality

For analyzing Control System Toolbox™ models tuned with looptune, use loopview.

Version History

Introduced in R2014a

See Also

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