Applying Signal Operators by Scripting

You can handle signal operators by scripting.

Notes:
  • The final script file must be saved in the directory where the result file used is located.
  • The below examples are created using the Modelica Scripting Window, but the Modelica Script Editor can also be used. For information about scripting, see Dymola Behavior Modeling User's Guide: Performing a Virtual Execution: Scripting..

This task shows you how to:

See Also
About Signal Operators

Insert Minimum, Maximum, Slew Rate, and Mean Signal Operators

You can insert a number of signal operators using the scripting function plotSignalOperator.

Note: You can use this scripting function to apply signal operators also on curves that are plotted against independent variables other than time, if the independent variables are rising over time.

Before you begin:
  • Display curves in a plotter.
  • Display the Modelica Scripting window.
  1. In the input command line of Modelica Scripting window, use the scripting function plotSignalOperator(variablePath, signalOperator, startTime, stopTime, id, result);

    The function plots a signal operator in the active plotter.

    1. Set variablePath to the name of the variable to have the signal operator. Example: "J1.a".
    2. Set signalOperator to the name of the signal operator. Possible values are:

      • SignalOperator.Min
      • SignalOperator.Max
      • SignalOperator.ArithmeticMean
      • SignalOperator.RectifiedMean
      • SignalOperator.RMS
      • SignalOperator.ACCoupledRMS
      • SignalOperator.SlewRate

    1. Set startTime to the start of the range where the signal operator is applied.
    2. Set stopTime to the end of the range where the signal operator is applied.
    3. Optional: Set id to the identity of the plotter.

      By default, the value is 0, meaning the last plotter.

  2. Press Enter to execute the function.
    The function is executed, and
    • The signal operator is plotted in the plotter.
    • The result is output in result in the plotSignalOperator function.

Insert Discrete Difference Signal Operators

You can insert discrete difference signal operators using the scripting function plotSignalDifference.

Note: You can use this scripting function to apply the signal operator also on curves that are plotted against independent variables other than time, if the independent variables are rising over time.

Before you begin:
  • Display curves in a plotter.
  • Display the Modelica Scripting window.
  1. In the input command line of Modelica Scripting window, use the scripting function plotSignalDifference(variablePath, startTime, stopTime, axis, id);

    The function plots a signal operator in the active plotter.

    1. Set variablePath to the name of the variable to have the signal operator. Example: "J1.a".
    1. Set startTime to the start of the range where the signal operator is applied.
    2. Set stopTime to the end of the range where the signal operator is applied.
    3. Set axis to 0 to use the left axis, and 1 to use the axis to the right.

      By default, the value is 0, meaning the left axis.

    4. Optional: Set id to the identity of the plotter.

      By default, the value is 0, meaning the last plotter.

  2. Press Enter to execute the function.
    The function is executed, and the signal operator is plotted in the plotter.

Insert Moving Average Signal Operators

You can insert moving average signal operators using the scripting function plotMovingAverage.

Note: You can use this scripting function to apply the signal operator also on curves that are plotted against independent variables other than time, if the independent variables are rising over time.

Before you begin:
  • Display curves in a plotter.
  • Display the Modelica Scripting window.
  1. In the input command line of Modelica Scripting window, use the scripting function plotMovingAverage(variablePath, startTime, stopTime, intervalLength, order, id);

    The function plots a signal operator in the active chart.

    1. Set variablePath to the name of the variable to have the signal operator. Example: "J1.a".
    1. Set startTime to the start of the range where the signal operator is applied.
    2. Set stopTime to the end of the range where the signal operator is applied.
    3. Set intervalLenght to specify the averaging inteval length.
    4. Optional: Set order to 1 if first-order derivatives should be computed and displayed.

      By default, the value is 0, meaning this option is not activated.

    5. Optional: Set id to the identity of the plotter.

      By default, the value is 0, meaning the last plotter.

  2. Press Enter to execute the function.
    The function is executed, and the signal operator is plotted in the plotter.

Insert First Harmonic and Total Harmonic Distortion Signal Operators

You can use the scripting function plotSignalOperatorHarmonic to handle first harmonic, and total harmonic distortion signal operators.

  1. In the input command line of Modelica Scripting window, use the scripting function plotSignalOperatorHarmonic(variablePath, signalOperator, startTime, stopTime, period, intervalLength, window, harmonicNo, id, result);

    The function plots a signal operator in the active plotter.

    1. Set variablePath to the name of the variable to have the signal operator. Example: "J1.a".
    2. Set signalOperator to the name of the signal operator. Possible values are:

      • SignalOperator.FirstHarmonic
      • SignalOperator.THD

    1. Set startTime to the start of the range where the signal operator is applied.
    2. Set stopTime to the end of the range where the signal operator is applied.
    3. Set period to the period length.
    4. Set intervalLength to the sampling interval length.
    5. Set window to the windowing function for the underlying FFT. Possible values are:

      • SignalOperators.Windows.Windowing.Rectangular (default value)
      • SignalOperators.Windows.Windowing.Hamming
      • SignalOperators.Windows.Windowing.Hann
      • SignalOperators.Windows.Windowing.FlatTop

    6. Set harmonicNo to the relevant harmonic number.
    7. Optional: Set id to the identity of the plotter.

      By default, the value is 0, meaning the last plotter.

  2. Press Enter to execute the function.
    The function is executed, and
    • The signal operator is plotted in the plotter.
    • The result is output in result in the plotSignalOperatorHarmonic function.

Insert Fast Fourier Transform (FFT) Signal Operators

You can use create a Fast Fourier Transform (FFT) signal operator for a signal by scripting.

One function is needed to compute the values for plotting, one function to perform the plotting.

In this scenario, you create a FFT signal operator on the signal J1.a from the simulation of the demo Coupled Clutches.

  1. From the Behavior Tools section of the action bar, click Coupled Clutches .
    The Coupled Clutches demo appears.
  2. From the Behavior Authoring section of the action bar, click Execute .
    The Coupled Clutches demo simulates.
  3. From the Behavior Tools section of the action bar, click Show/Hide the Scriptig Window .
    The Modelica Scripting window appears.
  4. The scripting function (freqpart, powers) = SignalOperators.Fourier.calculateFFT(resultFile, vars[:], tmin, tmax, npoints, maxfrequency=1e100, windowing=SignalOperators.Windows.Windowing.Rectangular) is used to compute the values that can be used for plotting. For the final function to be typed in the command input line of the Modelica Scripting window, see the result of this step.

    The first part (freqpart, powers) contains the result.

    1. Set resultFile to the name of the result file. Example: "CoupledClutches.mat".
    2. Set vars[:] to the variables to be plotted. Example: {"J1.a"}.
    3. Set tmin and tmax to the start time and stop time of the range where the signal operator should be applied. Use the values 0 and 1.5.
    4. Set npoints to the number of points. Use the value 1501 here.
    5. Optional: Set maxFrequency to the maximum frequency. The default value is 1e+100.
    6. Optional: Set window to the windowing function for the underlying FFT. Possible values are:

      • SignalOperators.Windows.Windowing.Rectangular (default value)
      • SignalOperators.Windows.Windowing.Hamming
      • SignalOperators.Windows.Windowing.Hann
      • SignalOperators.Windows.Windowing.FlatTop

    The result to be typed in the input command line of the Modelica Scripting window is now: (freqpart, powers) = SignalOperators.Fourier.calculateFFT("CoupledClutches.mat", {"J1.a"}, 0, 1.5, 1501, 1e+100, SignalOperators.Windows.Windowing.Rectangular);
  5. Press Enter to execute the function.
    The function is executed, and the result is computed.
  6. In the Modelica Scripting window, use the scripting function plotArrays(x[:], y[size(x, 1), :], legend[:], id, title, colors[size(y, 2), 3], patterns[size(y, 2)], markers[size(y, 2), thicknesses[size(y, 2)]) to plot the Fast Fourier Transform signal operator.
    1. Set x[:] to freqPart.
    2. Set y[size(x, 1), :] to powers.
    3. Set legend[:] to legend={"J1.a"}.
    4. Set id=1 to create the plot in a new plotter.
    5. For the rest of the parameters, you need not to change the default values in this scenario.
    The result in the input command line of the Modelica Scripting window is now: plotArrays(freqpart, powers, legend={"J1.a"}, id=1);
  7. Press Enter to execute the function.
    The function is executed, and the signal operator is plotted in a plotter.