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Merged
merged 11 commits into from
Mar 15, 2021
Merged

Add a block (based on time events) to calculate the extrema of a signal #3762

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bf2a239
Adds a block to calculate the extrema of a signal
dietmarw Feb 25, 2021
0d11698
Add missing HTML closing tag.
dietmarw Feb 25, 2021
4403702
Correct description strings.
dietmarw Feb 25, 2021
04d2357
Document the drawbacks of this block a bit clearer.
dietmarw Mar 1, 2021
e3d097e
Reducing the model by getting rid of intermediate variables.
dietmarw Mar 1, 2021
fcdce66
Adding function to store the time of extrema
dietmarw Mar 3, 2021
c9593be
added initialization of t_min and t_max as well as an example demonst…
AHaumer Mar 11, 2021
cfe0a96
remove vendor specific annotation
AHaumer Mar 13, 2021
51c5cf1
adapted example, added comparisonSignals.txt
AHaumer Mar 14, 2021
d0f692c
Remove ModelicaTest example since not needed
dietmarw Mar 15, 2021
c9110a5
Fix BOM and trailing white spaces.
dietmarw Mar 15, 2021
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107 changes: 107 additions & 0 deletions Modelica/Blocks/Math.mo
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2416,6 +2416,113 @@ Note: The output is updated after each period defined by 1/f.
textString="f=%f")}));
end RootMeanSquare;

block SignalExtrema "Calculate min and max of a signal"
extends Modelica.Blocks.Icons.Block;

parameter SI.Time Ts(start=0.01) "Sample time";
Modelica.Blocks.Interfaces.RealInput
u "Connector of Real input signal" annotation (Placement(
transformation(extent={{-140,-20},{-100,20}})));
Modelica.Blocks.Interfaces.RealOutput
y_min "Min of input signal" annotation (Placement(
transformation(extent={{100,-70},{120,-50}})));
Modelica.Blocks.Interfaces.RealOutput
y_max "Max of input signal" annotation (Placement(
transformation(extent={{100,50},{120,70}})));
discrete Real t_min "Sample time of last found minimum";
discrete Real t_max "Sample time of last found maximum";

protected
parameter SI.Time t0(fixed=false) "Start time of simulation";

initial equation
t0 = time;
y_min = u;
y_max = u;

equation
when sample(t0 + Ts, Ts) then
y_min = min(u, pre(y_min));
y_max = max(u, pre(y_max));
if y_min<pre(y_min) then
t_min = time;
t_max=pre(t_max);
elseif y_max>pre(y_max) then
t_max = time;
t_min=pre(t_min);
else
t_min=pre(t_min);
t_max=pre(t_max);
end if;
end when;
annotation (Icon(graphics={
Line(points={{-80,68},{-80,-80}}, color={192,192,192}),
Polygon(
points={{-80,90},{-88,68},{-72,68},{-80,90}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(points={{-90,0},{68,0}}, color={192,192,192}),
Polygon(
points={{90,0},{68,8},{68,-8},{90,0}},
lineColor={192,192,192},
fillColor={192,192,192},
fillPattern=FillPattern.Solid),
Line(
points={{-80,0},{-75.2,32.3},{-72,50.3},{-68.7,64.5},{-65.5,74.2},{-62.3,79.3},{-59.1,79.6},{-55.9,75.3},{-52.7,67.1},{-48.6,52.2},{-43,25.8},{-35,-13.9},{-30.2,-33.7},{-26.1,-45.9},{-22.1,-53.2},{-18,-56},{-14.1,-52.5},{-10.1,-45.3},{-5.23,-32.1},{8.44,13.7},{13.3,26.4},{18.1,34.8},{22.1,38},{26.9,37.2},{31.8,31.8},{38.2,19.4},{51.1,-10.5},{57.5,-21.2},{63.1,-25.9},{68.7,-25.9},{75.2,-20.5},{80,-13.8}},
smooth=Smooth.Bezier,
color={192,192,192}),
Text(extent={{-150,-110},{150,-150}},
textString="Ts=%Ts", lineColor={0,0,0}),
Line(
points={{-60,80},{52,80}},
color={0,0,0},
pattern=LinePattern.Dash), Text(
extent={{-150,150},{150,110}},
textString="%name",
lineColor={0,0,255}),
Text(extent={{60,70},{92,50}},
lineColor={0,0,0},
textString="max"),
Text(extent={{60,-50},{92,-70}},
lineColor={0,0,0},
textString="min"),
Line(
points={{-18,-56},{50,-56}},
color={0,0,0},
pattern=LinePattern.Dash)}), Documentation(info="<html>
<p>
This block calculates the min and the max of the input signal <code>u</code>
and stores the time at which the last min or max was reached in the
variables <code>t_min</code> and <code>t_max</code> respectively.
</p>
<h5>Note:</h5>
<p>The output is updated after each sample period defined by <code>Ts</code>.
This means that:</p>
<ul>
<li>The extrema will be approximate as it only return the extremas at the sampling points.</li>
<li>The sampling will generate many events which may slow down the simulation.</li>
</ul>

</html>", revisions="<html>
<table border=\"1\" cellspacing=\"0\" cellpadding=\"2\">
<tr>
<th>Version</th>
<th>Date</th>
<th>Author</th>
<th>Comment</th>
</tr>
<tr>
<td>1.0.0</td>
<td>2021-02-25</td>
<td><a href=\"https://github.com/dietmarw\">dietmarw</a>,
<a href=\"https://github.com/tinrabuzin\">tinrabuzin</a></td>
<td>Initial version</td>
</tr>
</table>
</html>"));
end SignalExtrema;

block Variance "Calculates the empirical variance of its input signal"
extends Modelica.Blocks.Icons.Block;
parameter SI.Time t_eps(min=100*Modelica.Constants.eps)=1e-7
Expand Down
8 changes: 8 additions & 0 deletions ModelicaTest/Blocks.mo
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Original file line number Diff line number Diff line change
Expand Up @@ -2038,4 +2038,12 @@ the whole homotopy transformation.</p>
</html>"));
end LimPID;

model SignalExtrema "Test of determining the extrema (min and max) of a signal"
extends Modelica.Icons.Example;
Modelica.Blocks.Math.SignalExtrema signalExtrema(Ts(displayUnit="ms") = 0.001) annotation (Placement(transformation(extent={{12,-10},{32,10}})));
Modelica.Blocks.Sources.ExpSine expSine(f=10, damping=-1) annotation (Placement(transformation(extent={{-32,-10},{-12,10}})));
equation
connect(expSine.y, signalExtrema.u) annotation (Line(points={{-11,0},{10,0}}, color={0,0,127}));
annotation (experiment(StopTime=1));
end SignalExtrema;
end Blocks;