genfrd
Generalized frequency response data (FRD) model
Description
Generalized FRD (genfrd
) models arise when
you combine numeric FRD models with models containing tunable components
(Control Design Blocks). genfrd
models keep track
of how the tunable blocks interact with the tunable components. For
more information about Control Design Blocks, see Generalized Models.
Construction
To construct a genfrd
model, use series
, parallel
, lft
, or connect
, or the arithmetic operators
+
, 
, *
,
/
, \
, and ^
, to combine a
numeric FRD model with control design blocks.
You can also convert any numeric LTI model or control design
block sys
to genfrd
form.
frdsys = genfrd(
converts
any static model or dynamic system sys
,freqs
,frequnits
)sys
to a generalized
FRD model. If sys
is not an frd
model object, genfrd
computes
the frequency response of each frequency point in the vector freqs
.
The frequencies freqs
are in the units specified
by the optional argument frequnits
. If frequnits
is
omitted, the units of freqs
are 'rad/TimeUnit'
.
frdsys = genfrd(
further
specifies the time units for converting sys
,freqs
,frequnits
,timeunits
)sys
to genfrd
form.
For more information about time and frequency units of genfrd
models,
see Properties.
Input Arguments

A static model or dynamic system model object. 

Vector of frequency points. Express frequencies in the unit
specified in 

Frequency units of the
Default: 

Time units of the
Default: 
Properties

Structure containing the control design blocks included in the
generalized LTI model or generalized matrix. The field names of You can change some attributes of these
control design blocks using dot notation. For example, if the generalized
LTI model or generalized matrix M.Blocks.a.Value = 1; 

Frequency points of the frequency response data. Specify 

Frequency units of the model.
The units Changing this property changes the overall system behavior.
Use Default: 

Input delay for each input channel, specified as a scalar value
or numeric vector. For continuoustime systems, specify input delays
in the time unit stored in the For a system with You can also set Default: 0 

Output delays. For a system with Default: 0 for all output channels 

Sample time. For continuoustime models, Changing this property does not discretize or resample the model. Default: 

Units for the time variable, the sample time
Changing this property has no effect on other properties, and
therefore changes the overall system behavior. Use Default: 

Input channel names, specified as one of the following:
Alternatively, use automatic vector expansion to assign input
names for multiinput models. For example, if sys.InputName = 'controls'; The input names automatically expand to You can use the shorthand notation Input channel names have several uses, including:
Default: 

Input channel units, specified as one of the following:
Use Default: 

Input channel groups. The sys.InputGroup.controls = [1 2]; sys.InputGroup.noise = [3 5]; creates input groups named sys(:,'controls') Default: Struct with no fields 

Output channel names, specified as one of the following:
Alternatively, use automatic vector expansion to assign output
names for multioutput models. For example, if sys.OutputName = 'measurements'; The output names automatically expand to You can use the shorthand notation Output channel names have several uses, including:
Default: 

Output channel units, specified as one of the following:
Use Default: 

Output channel groups. The sys.OutputGroup.temperature = [1]; sys.OutputGroup.measurement = [3 5]; creates output groups named sys('measurement',:) Default: Struct with no fields 

System name, specified as a character vector. For example, Default: 

Any text that you want to associate with the system, stored as a string or a cell array of
character vectors. The property stores whichever data type you
provide. For instance, if sys1.Notes = "sys1 has a string."; sys2.Notes = 'sys2 has a character vector.'; sys1.Notes sys2.Notes ans = "sys1 has a string." ans = 'sys2 has a character vector.' Default: 

Any type of data you want to associate with system, specified as any MATLAB^{®} data type. Default: 

Sampling grid for model arrays, specified as a data structure. For model arrays that are derived by sampling one or more independent variables, this property tracks the variable values associated with each model in the array. This information appears when you display or plot the model array. Use this information to trace results back to the independent variables. Set the field names of the data structure to the names of the sampling variables. Set the field values to the sampled variable values associated with each model in the array. All sampling variables should be numeric and scalar valued, and all arrays of sampled values should match the dimensions of the model array. For example, suppose you create a 11by1
array of linear models, sysarr.SamplingGrid = struct('time',0:10) Similarly, suppose you create a 6by9
model array, [zeta,w] = ndgrid(<6 values of zeta>,<9 values of w>) M.SamplingGrid = struct('zeta',zeta,'w',w) When you display M M(:,:,1,1) [zeta=0.3, w=5] = 25  s^2 + 3 s + 25 M(:,:,2,1) [zeta=0.35, w=5] = 25  s^2 + 3.5 s + 25 ... For model arrays generated by linearizing a Simulink^{®} model
at multiple parameter values or operating points, the software populates Default: 
Tips
You can manipulate
genfrd
models as ordinaryfrd
models. Frequencydomain analysis commands such asbode
evaluate the model by replacing each tunable parameter with its current value.
Version History
Introduced in R2011a
See Also
frd
 frdfun
 genss
 getValue
 chgFreqUnit