Before you can import time-domain data into the System Identification app, you must import the data into the MATLAB^{®} workspace, as described in Time-Domain Data Representation.
Note: Your time-domain data must be sampled at equal time intervals. The input and output signals must have the same number of data samples. |
To import data into the app:
Type the following command in the MATLAB Command Window to open the app:
systemIdentification
In the System Identification app window, select Import data > Time domain data. This action opens the Import Data dialog box.
Specify the following options:
Note:
For time series, only import the output signal and enter |
Input — Enter the MATLAB variable name (column vector or matrix) or a MATLAB expression that represents the input data. The expression must evaluate to a column vector or matrix.
Output — Enter the MATLAB variable name (column vector or matrix) or a MATLAB expression that represents the output data. The expression must evaluate to a column vector or matrix.
Data name — Enter the name of the data set, which appears in the System Identification app window after the import operation is completed.
Starting time — Enter the starting value of the time axis for time plots.
Sample time — Enter the actual sample time in the experiment. For more information about this setting, see Specifying the Data Sample Time.
Tip The System Identification Toolbox™ product uses the sample time during model estimation and to set the horizontal axis on time plots. If you transform a time-domain signal to a frequency-domain signal, the Fourier transforms are computed as discrete Fourier transforms (DFTs) using this sample time. |
(Optional) In the Data Information area, click More to expand the dialog box and enter the following settings:
Input Properties
InterSample — This options specifies the behavior of the input signals between samples during data acquisition. It is used when transforming models from discrete-time to continuous-time and when resampling the data.
zoh
(zero-order hold) indicates
that the input was piecewise-constant during data acquisition.
foh
(first-order hold)
indicates that the output was piecewise-linear during data acquisition.
bl
(bandwidth-limited behavior)
specifies that the continuous-time input signal has zero power above
the Nyquist frequency (equal to the inverse of the sample time).
Period —
Enter Inf
to specify a nonperiodic input. If the
underlying time-domain data was periodic over an integer number of
periods, enter the period of the input signal.
Note: If your data is periodic, always include a whole number of periods for model estimation. |
Channel Names
Input — Enter a string to specify the name of one or more input channels.
Tip Naming channels helps you to identify data in plots. For multivariable input-output signals, you can specify the names of individual Input and Output channels, separated by commas. |
Output — Enter a string to specify the name of one or more output channels.
Physical Units of Variables
Input — Enter a string to specify the input units.
Tip When you have multiple inputs and outputs, enter a comma-separated list of Input and Output units corresponding to each channel. |
Output — Enter a string to specify the output units.
Notes — Enter comments about the experiment or the data. For example, you might enter the experiment name, date, and a description of experimental conditions. Models you estimate from this data inherit your data notes.
Click Import. This action adds a new data icon to the System Identification app window.
Click Close to close the Import Data dialog box.