Simulink Control Design™ - MathWorks

Results and Recommended Actions

Condition Recommended Action

Source blocks exist whose
output reaches linearization
output points currently marked
on the model.

Consider holding these source blocks constant during frequency

response estimation.

Use the frest.findSources command to identify time-varying

source blocks at the command line. Then use the

BlocksToHoldConstant option of frestimateOptions to pass

these blocks to the frestimate command. For example,

% Get linearization I/Os from the model.

mdl = 'scdengine';

io = getlinio(mdl);

% Find time-varying source blocks.

blks = frest.findSources(mdl,io);

% Create options set with blocks to hold constant.

opts = frestimateOptions;

opts.BlocksToHoldConstant = blks;

% Run estimation with the options.

in = frest.Sinestream;

sysest = frestimate(mdl,io,in,opts);

For more information and examples, see the

frest.findSources and frestimateOptions reference

pages.

Tip

Sometimes, the model includes referenced models containing source blocks in the signal

path of an output linearization point. In such cases, set the referenced models to normal

simulation mode to ensure that this check locates them. Use the set_param command to

set SimulationMode of any referenced models to Normal before running the check.

See Also

• “Estimate Frequency Response Using Linear Analysis Tool” on page 5-7


• “Effects of Time-Varying Source Blocks on Frequency Response Estimation” on page 5-
  60


• frest.findSources reference page


• frestimateOptions reference page

Simulink Control Design Checks