input = frest.Sinestream(sys) creates
a signal with a series of sinusoids based on the dynamics of a linear
system sys.
input = frest.Sinestream('OptionName',OptionValue) creates
a signal with a series of sinusoids, where each sinusoid frequency
lasts for a specified number of periods, using the options specified
by comma-separated name/value pairs.
To view a plot of your input signal, type plot(input).
To obtain a timeseries for your input signal, use the generateTimeseries command.
Input Arguments
sys
Linear system for creating a sinestream signal based on the
dynamic characteristics of this system. You can specify the linear
system based on known dynamics using tf, zpk, or ss.
You can also obtain the linear system by linearizing a nonlinear system.
The resulting sinestream signal automatically sets these options
based on the linear system:
'Frequency' are the frequencies
at which the linear system has interesting dynamics.
'SettlingPeriods' is the number
of periods it takes the system to reach steady state at each frequency
in 'Frequency'.
'NumPeriods' is (3 + SettlingPeriods)
to ensure that each frequency excites the system at specified amplitude
for at least three periods.
For discrete systems only, 'SamplesPerPeriod' is
set such that all frequencies have the same sample time as the linear
system.
Other sinestream options have default values.
'OptionName',OptionValue
Signal characteristics, specified as comma-separated pairs of
option name string and the option value.
Option Name
Option
Value
'Frequency'
Signal frequencies, specified as either a scalar or a vector
of frequency values.
Default: logspace(1,3,50)
'Amplitude'
Signal amplitude at each frequency, specified as either:
Scalar to set all frequencies to same value
Vector to set each frequencies to a different value
Default: 1e-5
'SamplesPerPeriod'
Number of samples for each period for each signal frequency,
specified as either:
Scalar to set all frequencies to same value
Vector to set each frequencies to a different value
Default: 40
'FreqUnits'
Frequency units:
'rad/s'—Radians per second
'Hz'— Hertz
Default: 'rad/s'
'RampPeriods'
Number of periods for ramping up the amplitude of each sine
wave to its maximum value, specified as either:
Scalar to set all frequencies to same value
Vector to set each frequencies to a different value
Use this option to ensure a smooth response when your
input amplitude changes. Default: 0
'NumPeriods'
Number of periods each sine wave is at maximum amplitude, specified
as either:
Scalar to set all frequencies to same value
Vector to set each frequencies to a different value
Default: max(3–RampPeriods+SettlingPeriods,,
2)
'SettlingPeriods'
Number of periods corresponding to the transient portion of
the simulated response at a specific frequency, before the system
reaches steady state, specified as either:
Scalar to set all frequencies to same value
Vector to set each frequencies to a different value
Before performing the estimation, frestimate discards this number of
periods from the output signals.
Default: 1
'ApplyFilteringInFRESTIMATE'
Frequency-selective FIR filtering of the input signal before
estimating the frequency response using frestimate.
'on' (default)
'off'
For more information, see the frestimate algorithm.
'SimulationOrder'
The order in which frestimate injects the
individual frequencies of the input signal into your Simulink^{®} model
during simulation.
'Sequential' (default) — frestimate injects
one frequency after the next into your model in a single Simulink simulation
using variable sample time. To use this option, your Simulink model
must use a variable-step solver.
'OneAtATime' — frestimate injects
each frequency during a separate Simulink simulation of your
model. Before each simulation, frestimate initializes
your Simulink model to the operating point specified for estimation.
If you have Parallel Computing Toolbox™ installed, you can run each
simulation in parallel to speed up estimation using parallel computing.
For more information, see Speeding Up Estimation Using Parallel Computing.
Examples
Create a sinestream signal having several different frequencies.
For each frequency, specify an amplitude, a number of periods at maximum
amplitude, a ramp-up period, and a number of settling periods.