frest.createStep
Package: frest
Create step input signal
Description
A step input signal has an initial value of 0 and transitions
to a specified step size value after a specified step time. When performing frequency response
estimation, step inputs are quick to simulate and can be useful as a first try when you do not
have much knowledge about the system you are trying to estimate. However, the amplitude of the
excitation decreases rapidly with increasing frequency. Therefore, step signals are best used
to identify low-order plants where the slowest poles are dominant. Step inputs are not
recommended for estimation across a wide range of frequencies.
When you use a step input signal for estimation, the frequencies returned in the estimated
frd model depend on the length and sampling time of the signal. They
are the frequencies obtained in the fast Fourier transform of the input signal (see the
Algorithm section of frestimate).
For more information on input signals for frequency response estimation, see Estimation Input Signals.
input = frest.createStep(Name,Value)
Examples
Create Step Input Signal
Create a step input signal with a default sample time and the following properties:
Step time of
5secondsStep size of
0.1Total duration of
15seconds
input = frest.createStep('StepTime',5,'StepSize',0.1,'FinalTime',15)
timeseries
Common Properties:
Name: 'Created with frest.createStep utility'
Time: [15001x1 double]
TimeInfo: tsdata.timemetadata
Data: [15001x1 double]
DataInfo: tsdata.datametadata
Plot the step signal.
plot(input)
