View source for OpenModelica/C3/Component-oriented-modeling/English-timed


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||''' Time '''
||'''Narration'''

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||00:01
|| Welcome to the '''spoken tutorial''' on '''Component oriented modeling'''.

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||00:06
|| In this tutorial, we are going to learn:
how to '''instantiate''' a '''model''',

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||00:12
||how to define '''connector class''' and   
how to develop model of a simple electric circuit using '''component models'''.

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|| 00:21
|| To record this tutorial, I am using:  '''OpenModelica 1.9.2''',  '''Ubuntu Operating System version 14.04'''.
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|| 00:31
|| But this process is identical to any of the following '''operating system'''s.

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|| 00:39
|| To understand and practice this tutorial, you need to know  how to define a class in '''Modelica'''.

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|| 00:45
|| You need to know how to define a '''package''' and '''Icon and Diagram Views'''.

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|| 00:51
|| Prerequisite tutorials are mentioned on our website. Please go through them.

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|| 00:57
|| Now let us learn more about '''Class Instantiation'''.
 
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|| 01:02
|| '''Modelica classes''' can be instantiated. 

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|| 01:06
||For example, an individual can be considered as an instance of '''human being''' '''class'''. '''Instance''' of a '''class''' has the same variables and equations as the '''class''' itself.

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|| 01:20
|| The syntax for '''Class Instantiation''' is as shown.

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|| 01:25
|| Now, let us understand this through an example.  Please download and '''save''' all the files available on our website.

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|| 01:34
|| Let me switch to '''OMEdit'''.  The following files are already open in '''OMEdit''': '''classInstantiationExample''' and '''simpleCircuit'''.

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|| 01:48
|| Double-click on '''classInstantiationExample'''.  Let us discuss more about this '''class''' now.

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|| 01:56
|| Let me shift '''OMEdit''' window to the left for better visibility.

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|| 02:02
|| Here, I have instantiated the '''bouncingBall class''' to create two '''object'''s named   '''object1''' and '''object2'''. 
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|| 02:12
|| Note that each '''instance''' has different start values for the height variable '''h'''. 

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|| 02:20
|| Please refer prerequisite tutorials for more information on the '''bouncingBall''' model. 

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|| 02:27
|| Let us simulate this class now. 

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|| 02:30
|| Click on '''Simulate''' button in the toolbar. 

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|| 02:34
|| The class did not simulate and it threw up an '''error'''. 

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|| 02:39
|| This is because '''bouncingBall class''' is not open in '''OMEdit'''.

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|| 02:45
|| Open '''bouncingBall class''' which you downloaded from the website. 

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|| 02:50
|| Now, simulate this '''class''' once again.  Close the pop-up window.

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|| 02:56
|| Note that the '''class''' simulates successfully this time around. 

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|| 03:01
|| This exercise demonstrates that a '''class''' should be open in '''OMEdit''' to be instantiated.

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|| 03:09
|| Expand '''object1''' variables in the '''variables browser'''.

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|| 03:14
|| Note that the variables listed here are declared in '''bouncingBall class'''. 

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|| 03:20
|| These variables are also a part of '''object1''' and '''object2''' since they are just instances of the '''bouncingBall class'''.

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||03:30
||Now, delete the result and go back to the slides.

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|| 03:37
|| '''Component orientation''' sets '''Modelica''' apart from other modeling and simulation softwares. 

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|| 03:43
|| It is the single most important feature of '''Modelica'''.

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|| 03:48
|| '''component''' models represent single physical phenomenon.

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|| 03:53
|| They can be instantiated and connected to produce desired effect.

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|| 03:59
|| For example, an '''RLC circuit''' could be developed from '''resistor, inductor''' and '''capacitor''' models.

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|| 04:08
|| '''Acausal connectors''' serve as the interface between component instances.

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|| 04:15
|| They are defined using '''connector class'''. For example, '''pins''' can be used as '''connectors''' for electrical components.
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|| 04:24
|| We will learn more about this when we try to simulate the example for an electric circuit.

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|| 04:30
|| '''Connectors''' contain across and flow variables and they cannot contain equations.

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|| 04:38
|| Now, let us simulate this '''Electric Circuit''' shown in the '''slide'''. 

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|| 04:43
|| The voltage of battery is given by '''{VoSin(2pift)}''', where '''Vo''' is '''10''' Volts, '''f''' is '''1''' Hz and the resistance is '''5''' ohm. 

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|| 04:59
|| Let us take a look at the '''Solution Methodology''' to model the '''electric circuit''' shown in previous slide.
Note that any '''Resistor''' and '''Voltage Source''' have two pins: '''Positive''' and '''Negative'''.

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|| 05:14
||  Hence, define a '''connector''' named '''pin'''.

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|| 05:18
||  Define a '''class''' named '''Ground''' with one instance of '''pin connector'''. 
 
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|| 05:24
|| Define a '''class''' named '''Resistor'''.

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|| 05:28
||  The '''Resistor''' class should have two instances of the '''pin connector''': '''Positive pin''' and the '''Negative pin'''.
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|| 05:36
|| Define a '''class''' named '''VoltageSource''' with two instances of '''pin connector''' as we have seen in the case of '''resistor class'''.

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|| 05:46
|| Define a '''class''' named '''simpleCircuit'''.  '''simpleCircuit''' should have instances of '''Resistor''' and '''VoltageSource'''.

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|| 05:56
||  Connect the respective '''pins''' of '''Resistor''', '''ground''' and the '''VoltageSource'''.

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|| 06:02
|| The component models required have already been programmed. 

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|| 06:07
|| Hence, I shall demonstrate only the last two steps of '''Solution Methodology'''. 

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|| 06:13
|| Let me switch to '''OMEdit'''.  Go back to the '''Modeling perspective'''.

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|| 06:19
|| Let me shift '''OMEdit''' window to the right. 

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|| 06:23
|| Expand '''simpleElectricCircuit'''package in the '''Libraries Browser'''. 

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|| 06:29
|| Note that this package has five '''classes''' named:  '''pin''',  '''Ground''',  '''Resistor''',   '''Voltage Source''' and   '''circuit'''. 

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|| 06:40
||Double-click on '''simpleElectricCircuit'''. Close '''ClassinstantiationExample'''.

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|| 06:48
||Let me shift '''OMEdit''' window to the left once again, for better visibility.

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|| 06:54
|| '''Modelica.SIunits''' package has been '''import'''ed in the package '''simpleElectricCircuit'''.

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|| 07:02
||Hence, '''type''' definitions in that package can be used without reference to their full names.

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|| 07:10
|| Let us try to understand '''pin connector'''.  Scroll-down a little bit.

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|| 07:17
|| '''Pin''' is defined using '''connector class'''.

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|| 07:21
|| '''Voltage''' and '''current''' are the variables that a '''pin''' exchanges with its surroundings.

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|| 07:27
|| '''Potential''' at the '''pin''' is defined by '''v'''.  '''Voltage''' and '''Current''' are '''types''' defined in '''SIunits''' package of '''Modelica library'''.

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|| 07:40
|| '''Voltage''' across a component causes a current to flow through it.

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|| 07:44
||Hence, '''current''' is a '''flow''' variable and is defined using '''flow''' keyword.

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|| 07:50
|| '''pin connector''' also has an '''Icon view''' specified by '''annotations''' as shown.

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|| 07:57
|| Now, let us discuss a little about '''Resistor class.'''  Scroll down a little more.

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|| 08:04
|| As discussed in the '''Solution Methodology''', '''Resistor class''' has two instances of '''pin connector'''.

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|| 08:12
||'''p''' stands for '''positive pin''' and '''n''' stands for '''negative pin'''.

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|| 08:18
|| Now, let me show you how to instantiate a '''class''' using the '''drag and drop''' functionality of '''OMEdit'''.

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|| 08:26
|| To demonstrate that, let me open a new '''class''' using '''Ctrl + N'''.

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|| 08:32
|| Name this '''class example1''' and press '''Ok'''.  Shift '''OMEdit''' window to the right.

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|| 08:41
|| Go to '''Diagram View''' if the class opens in '''Text View'''.

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|| 08:46
|| Now, let me instantiate '''pin''' class.

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|| 08:51
||Left-click on '''pin''' icon in '''Libraries Browser'''. 

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|| 08:55
||Hold and drag the icon to the '''diagram''' layer.  Drop it at any location on the canvas. 

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||09:04
||We have now created an '''instance''' of '''pin class'''. 

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|| 09:09
||You may also change the dimensions and location after dropping it, as shown.

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|| 09:16
|| Now, let us see how this '''class''' is instantiated in '''Text View'''. Go to '''Text View'''.

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|| 09:22
|| Notice the '''command''' for instantiation of '''class pin''' and an '''annotation''' based on its placement in '''Diagram View'''. 

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|| 09:33
||Hence, creating an '''instance''' of a '''class''' in '''Diagram View''' automatically reflects in the '''Text View'''. Now, let me close '''example1''' tab.

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|| 09:45
||Let us learn how to model '''electric circuit''' that we saw in the slides.

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|| 09:51
|| Double-click on '''Circuit''' icon which is also a part of '''simpleElectricCircuit''' package. 

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|| 09:58
||This '''class''' already has our circuit of interest assembled, as can be seen in its '''Diagram View'''.  It is ready to be simulated.

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|| 10:09
|| But let us build the same '''circuit''' in a new file. 

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|| 10:14
||We shall use '''drag and drop''' functionality that we have just learnt about. 

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||10:19
|| Press '''Ctrl + N'''.  Name this file '''circuit(underscore)construction'''. Press '''OK'''.

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|| 10:28
|| Switch to '''Diagram View''', if it opens in '''Text View'''.

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|| 10:32
|| Select, drag and drop the '''VoltageSource''' icon from '''Libraries Browser'''.  You may change its dimensions as you wish.

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|| 10:43
|| Similarly, select, drag and drop the '''Resistor''' icon from '''Libraries Browser'''.

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|| 10:50
|| Do the same with '''Ground class'''.

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|| 10:54
|| Now, we need to connect the respective '''pins''' of each component.

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|| 11:00
|| Let us first connect the '''positive pin''' of '''Voltage Source''' to the '''positive pin''' of '''Resistor'''. 

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|| 11:07
||Hover over the left pin of '''Voltage Source'''. 

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|| 11:11
||The text that appears indicates that this is the '''positive pin p'''. 

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|| 11:17
|| Left click on this '''pin''' and drag the '''cursor''' closer to the left '''pin''' of '''Resistor'''. 

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|| 11:24
||Leave the '''mouse''' when the appearance of cursor changes to '''cross''' from an arrow.

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|| 11:30
|| Similarly, connect the '''negative pin''' of '''resistor''' to the '''negative pin''' of '''voltage source'''.

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|| 11:38
|| We have not mentioned the connections with '''Ground''' in the circuit diagram. 

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|| 11:44
||But, we need to connect the '''negative pins''' of '''Resistor''' and '''Voltage Source''' to '''Ground''' individually. 

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|| 11:51
||This ensures a reference point for '''potential''' in the '''circuit'''. 

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|| 11:57
|| Now, this '''class''' is complete.  '''Save''' the '''class''' by pressing '''Ctrl + S'''. 

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|| 12:04
|| Click on '''Simulate''' button.  Close the pop -up window.

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||12:10
||The '''class''' has simulated successfully. 

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|| 12:14
||Let me shift '''OMEdit''' window to the left, for better visibility of '''Variables browser'''.

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|| 12:20
|| Expand '''Resistor''' column in the '''Variables Browser''' and select '''Ir'''. 

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|| 12:28
||Note that the profile is '''sinusoidal''' as expected

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|| 12:33
||since the '''Voltage Source''' is an '''AC''' source instead of '''DC'''.

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|| 12:38
|| Hence, we have created a model from its component parts and simulated it. 

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|| 12:44
||We shall learn more about the '''Resistor''' and '''Voltage Source classes''' that we used here in the next tutorial.

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|| 12:52
|| Let me switch to the slides. 

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|| 12:55
||This brings us to the end of this tutorial.

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|| 12:59
|| As an assignment, construct an '''electric circuit''' with two '''resistors''' in '''series'''  with one '''Voltage Source'''. 

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|| 13:07
||Use the component models for '''Voltage source''' and '''Resistor''' provided in '''simple electric circuit''' package.

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|| 13:15
|| Watch the video available at the following link. It summarizes '''Spoken Tutorial project'''.
http://spoken-tutorial.org/What_is_a_Spoken_Tutorial

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|| 13:21
|| We conduct workshops using '''spoken tutorials'''. Please contact us.

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|| 13:26
|| If you have questions from this tutorial, please visit the website mentioned below.

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|| 13:32
|| We coordinate coding of solved examples of popular books.  Please visit our website.

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||13:38
|| We help migrate commercial simulator labs to '''OpenModelica'''.  Please visit the following website for more information.

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|| 13:47
|| '''Spoken Tutorial Project''' is funded by '''NMEICT, MHRD''' Government of India.

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|| 13:54
|| We thank the development team of '''OpenModelica''' for their support. Thank you.