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#: ../../source/components/components/speed_comps.rst:4
msgid "Speed Measurement Revisited"
msgstr ""

#: ../../source/components/components/speed_comps.rst:6
msgid ""
"Recall our previous discussion on :ref:`speed-measurement`.  That discussion"
" took place before we had introduced the idea of building reusable "
"components.  As a result, adding equations associated with the various speed"
" measurement techniques was awkward."
msgstr ""

#: ../../source/components/components/speed_comps.rst:11
msgid ""
"In this section, we'll revisit that topic and all of the various speed "
"estimation techniques discussed there.  As before, we assume that we have an"
" existing model of the \"plant\" (the system whose speeds we wish to "
"measure).  But this time, we'll create reusable component models for "
"different speed estimation algorithms and add them to the plant model as "
"graphical components."
msgstr ""

#: ../../source/components/components/speed_comps.rst:19
msgid "Plant Model"
msgstr ""

#: ../../source/components/components/speed_comps.rst:21
msgid ""
"We'll start with our \"plant model\".  It is identical in behavior to the "
"system we used in our previous discussion of :ref:`speed-measurement` and "
"when rendered as a schematic, looks like this:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:32
msgid "The source code for the underlying Modelica model is:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:37
msgid ""
"In the remaining sections we will create models that use different "
"approximation techniques to measure the speed of the ``inertia1`` component "
"in our plant model."
msgstr ""

#: ../../source/components/components/speed_comps.rst:41
msgid ""
"Before we look at the different speed approximation methods, let's have a "
"look at the actual speed response from our plant model."
msgstr ""

#: ../../source/components/components/speed_comps.rst:47
msgid ""
"Note that this is exactly the same response we saw when we initially covered"
" this topic."
msgstr ""

#: ../../source/components/components/speed_comps.rst:53
msgid "Sample and Hold Sensor"
msgstr ""

#: ../../source/components/components/speed_comps.rst:55
msgid ""
"Previously, we discussed the :ref:`sample-and-hold` approach to speed "
"measurement.  Here we will revisit this topic, but encapsulate the speed "
"approximation in a reusable sensor model.  The following model implements "
"the \"sample and hold\" approximation to speed measurement:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:63
msgid ""
"Behaviorally, there is not difference between this estimation technique and "
"our previous implementation of :ref:`sample-and-hold`. But our approach is "
"different this time because we have wrapped that estimation technique in a "
"reusable component model."
msgstr ""

#: ../../source/components/components/speed_comps.rst:68
msgid ""
"We have once again saved ourselves some trouble by utilizing a ``partial`` "
"model to represent code that will be common across our various sensor "
"models.  As we can see from the definition of the ``SpeedSensor`` model:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:76
msgid ""
"We can see from the ``SpeedSensor`` model that the output signal is named "
"``w``.  But we also see that ``SpeedSensor`` inherits from another model in "
"the Modelica Standard Library, ``PartialAbsoluteSensor``.  The "
"``PartialAbsoluteSensor`` model is defined as:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:94
msgid ""
"In addition to providing a nice icon, the ``PartialAbsoluteSensor`` model "
"features a rotational connector, ``flange``.  Furthermore, the model assumes"
" that the sensor model is completely passive (*i.e.,* it has no impact on "
"the system it is sensing) since it applies zero torque at the connection "
"point."
msgstr ""

#: ../../source/components/components/speed_comps.rst:100
msgid ""
"To test this model, we simply extend from our ``Plant`` model, add an "
"instance of the ``SampleHold`` sensor and connect it to the ``inertia``, "
"*e.g.*,"
msgstr ""

#: ../../source/components/components/speed_comps.rst:107
msgid "When assembled, our final system looks like this:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:115
msgid ""
"If we simulate this system for 5 seconds, we can compare the actual speed of"
" the inertia with the signal returned from our sensor:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:121
msgid ""
"These results are identical to the results from our previous discussion of "
"the :ref:`sample-and-hold` approach."
msgstr ""

#: ../../source/components/components/speed_comps.rst:125
msgid "Interval Measurement"
msgstr ""

#: ../../source/components/components/speed_comps.rst:127
msgid ""
"Now let us turn our attention to the :ref:`interval-measurement` technique."
"  Again, we will create a reusable component model by extending from our "
"``Sensor`` model.  This time, the implementation will use the time between "
"teeth to estimate speed:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:135
msgid ""
"Adding this sensor to our plant model is as simple as creating the following"
" Modelica model:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:141
msgid "When assembled, our system model looks like this:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:149
msgid ""
"Simulating this system, we get the following results for estimated speed:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:154
msgid ""
"As we saw in our previous discussion of the :ref:`interval-measurement` "
"technique, the quality of the estimated signal is severely reduced if we "
"reduce the number of teeth.  The previous plot used a sensor with 200 teeth "
"per rotation.  If we plot the shaft angle with respect to the bracketing "
"teeth angles, we see that the shaft cannot move very far without triggering "
"a measurement:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:164
msgid ""
"On the other hand, if we reduce the number of teeth per rotation down to 20,"
" we get the following results:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:170
msgid ""
"Plotting the teeth angles that bracket the current shaft angle, we see that "
"crossings are far less frequent, and, as a result the accuracy of the "
"measurement is greatly reduced:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:177
msgid ""
"Again, we can validate our component-oriented sensor implementations by "
"noting that these results are identical to the results presented during our "
"previous discussion of the :ref:`interval-measurement` technique."
msgstr ""

#: ../../source/components/components/speed_comps.rst:183
msgid "Pulse Counter"
msgstr ""

#: ../../source/components/components/speed_comps.rst:185
msgid ""
"Finally, we have the :ref:`pulse-counting` approach.  Again, the estimation "
"technique can be wrapped in a reusable component that extends from the base "
"``Sensor`` model:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:192
msgid "and then added to our overall ``Plant`` model:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:197
msgid "The resulting system, when rendered, looks like this:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:205
msgid ""
"Simulating the system, we see that the results are the same as in our "
"previous discussion of :ref:`pulse-counting`:"
msgstr ""

#: ../../source/components/components/speed_comps.rst:212
msgid "Conclusion"
msgstr ""

#: ../../source/components/components/speed_comps.rst:214
msgid ""
"The discussion of :ref:`speed-measurement` earlier in the book went into "
"great detail about the various measurement techniques that can be used to "
"estimate the speed of a rotating shaft.  The purpose of this section was not"
" to revisit that discussion but rather to show how the estimation techniques"
" presented earlier can benefit greatly from the component-oriented features "
"in Modelica.  As we have seen, all of these techniques can be nicely "
"encapsulated in component models.  The result is that utilizing these "
"different estimation techniques is now as easy as dragging and dropping one "
"of these sensor models into a system and attaching it to the rotating "
"element whose speed you wish to measure."
msgstr ""
