OpenModelica/C2/Developing-an-equation-based-model/English-timed - Revision history

PoojaMoolya at 09:52, 16 August 2019

2019-08-16T09:52:05Z

Sandhya.np14 at 11:15, 17 August 2018

2018-08-17T11:15:00Z

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Sandhya.np14 at 10:31, 17 August 2018

2018-08-17T10:31:25Z

Sandhya.np14 at 09:09, 17 August 2018

2018-08-17T09:09:27Z

Jyotisolanki: Created page with "{| border=1 ||''' Time ''' ||'''Narration''' |- ||00:01 ||Welcome to the spoken tutorial on '''Developing an equation based model'''. |- || 00:06 || In this tutorial, we are..."

2017-09-26T10:38:23Z

Created page with "{| border=1 ||''' Time ''' ||'''Narration''' |- ||00:01 ||Welcome to the spoken tutorial on '''Developing an equation based model'''. |- || 00:06 || In this tutorial, we are..."

New page

{| border=1
||''' Time '''
||'''Narration'''

|-
||00:01
||Welcome to the spoken tutorial on '''Developing an equation based model'''.

|-
|| 00:06
|| In this tutorial, we are going to learn: How to create a textual model in '''OMEdit''' and simulate it.

|-
|| 00:14
||How to declare variables and equations.

|-
|| 00:17
||How to use '''Simulation Setup''' toolbox.

|-
|| 00:21
|| To record this tutorial, I am using '''OpenModelica 1.9.2 ''' and '''Ubuntu Linux Operating System 14.04'''

|-
|| 00:32
||But, this process is identical in '''Windows, Mac OS X '''or''' FOSSEE OS on ARM'''.

|-
|| 00:40
|| To understand this tutorial, you need to know equation-based modeling of physical systems.

|-
|| 00:48
|| Let us simulate the motion of a ball of mass ''''m'''', which is under '''free fall due to gravity'''.

|-
|| 00:54
||The height of the ball from the surface of Earth is represented by variable '''h'''.

|-
|| 00:59
||The velocity of the ball is represented by variable '''v'''.

|-
|| 01:04
||'''Acceleration due to gravity''' is represented by '''g''' and is assumed to be constant.

|-
|| 01:10
||Variables directed away from the surface of Earth, are considered positive.

|-
|| 01:16
|| The '''equations of motion''' for a freely falling body, are as follows:'''dh/dt = v''' , '''dv/dt = g'''

|-
|| 01:27
||The value of '''h''' at time '''t = 0''' is '''30''' m and the value of '''v''' at time '''t = 0''' is '''0'''.

|-
|| 01:37
|| Now let me go to '''OMEdit'''. I have already launched it on my system.

|-
||01:43
|| To open '''OMEdit '''on '''Ubuntu Linux Operating System''', click on '''Dash Home '''icon, which appears at the top left, in '''launcher'''.

|-
||01:53
||Type '''OMEdit''' in the '''search bar'''.

|-
|| 01:56
||Click on the '''OMEdit''' icon.

|-
||01:59
||On clicking '''OMEdit''' icon, you see a window such as this.

|-
|| 02:06
||This window is known as '''"Welcome perspective"'''.

|-
|| 02:09
||'''OMEdit''' by default, opens in the '''"Welcome perspective"'''

|-
|| 02:14
|| At the bottom right-hand corner, you can locate buttons for '''‘Welcome’, ‘Modeling’''' and '''‘Plotting’ perspectives'''.

|-
|| 02:23
|| click on''' ‘Modeling perspective’'''.

|-
||02:26
||'''‘Modeling perspective’''' has now opened.

|-
|| 02:29
|| I will be referring to the area between '''Libraries Browser''' on the left, '''Messages Browser''' at the bottom and '''Toolbar''' on the top, as the '''modeling area'''.

|-
|| 02:41
|| The '''toolbar''' has buttons related to '''file operations, graphical view''' and '''simulation'''.

|-
|| 02:51
||We will learn more about these buttons, as we go along.

|-
|| 02:55
|| Now, we shall use''' ‘freeFall’ class''' file provided in the '''Code Files''' link on our '''Spoken Tutorial webpage'''.

|-
|| 03:02
||Please download this file and save it on your system.

|-
|| 03:07
|| To open this '''class''', go to the '''File''' menu in '''Menu bar'''.

|-
|| 03:13
||Click on '''Open Model/Library File'''

|-
|| 03:17
|| Locate '''freeFall''' file that you downloaded and saved on your system and open it.

|-
|| 03:24
|| You may also use the tool named '''Open Model/Library File''', that my cursor is pointing to, for opening a file.

|-
|| 03:34
|| Note that '''freeFall''' icon appears in the '''Libraries Browser'''.

|-
|| 03:39
||'''Libraries Browser''' shows all '''classes''' that are loaded in a session of '''OMEdit'''.

|-
|| 03:45
|| Right click on '''freeFall''' icon and select '''View Class'''.

|-
|| 03:52
|| The '''class''' has now opened in '''Diagram''' view.

|-
|| 03:56
||Do not worry if the '''class''' does not open in '''Diagram''' view.

|-
|| 04:00
||I shall show you how to switch between different views.

|-
||04:04
||Go to the top of ''' Modeling area'''.

|-
|| 04:07
||Note that the second button stands for '''Diagram''' view.

|-
|| 04:10
|| Third button is '''Text View'''.

|-
|| 04:13
||Click on it to switch to '''Text View'''.

|-
|| 04:17
||The '''class''' has now opened in '''Text''' view.

|-
||04:20
||Note that the first button stands for '''Icon View'''.

|-
|| 04:24
||We will learn more about '''Icon view '''and '''Diagram view '''later on.

|-
|| 04:29
|| You may also create a new '''class''' named '''freeFall''' and type the required information.

|-
|| 04:36
|| To create a new '''class''', go to '''File''' menu.

|-
|| 04:40
||Select '''New Modelica Class'''.

|-
||04:43
|| A dialog box pops up, as shown.

|-
|| 04:46
||In the '''Name''' field of this dialog box, type '''freeFall'''.

|-
|| 04:51
||I am using a different name '''freeFall1''' since '''freeFall class''' is already open in '''OMEdit'''.

|-
||04:58
||Note that two '''classes''' cannot have the same name.

|-
|| 05:03
|| Click on '''Specialization''' drop-down menu. Select '''Class'''. Click on '''Ok'''.

|-
|| 05:10
|| A new '''class''' has been created.

|-
|| 05:13
||You may also use the '''tool''' named '''New Modelica class''' to open a new '''class'''.

|-
||05:20
||Let me delete '''annotation section'''.

|-
|| 05:23
|| Now, you may type the required information here and save this '''class'''.

|-
|| 05:29
||To save this '''class''', go to '''File''' menu in '''Menu bar''' and click on '''Save'''.

|-
|| 05:36
|| Choose an appropriate location for this file and save it.

|-
|| 05:41
|| Now, let us understand the syntax of '''Modelica''' using '''freeFall class'''.

|-
|| 05:47
||So switch to '''freeFall class'''.

|-
||05:49
||Go to top of '''Modelling area'''. Click on '''freeFall''' tab.

|-
||05:54
||Programs in '''Modelica''' are arranged in the form of '''classes'''.

|-
|| 05:58
|| The first line of a '''class''' defines its name.

|-
|| 06:02
||The name of this '''class '''is '''freeFall'''.

|-
|| 06:05
|| Every '''class''' must have an '''end statement''' to indicate where the '''class''' ends.

|-
|| 06:11
|| This '''class '''has '''variable declarations '''and '''equations'''.

|-
|| 06:15
||Let me show you how to declare '''variables'''.

|-
|| 06:18
|| '''Real''' represents '''data-type'''.

|-
|| 06:21
|| '''h''' represents height of ball from surface of Earth.

|-
||06:25
||'''start''' is an attribute of '''Real variable'''.

|-
|| 06:29
|| Every '''data-type''' has certain attributes, which specify useful information related to '''variables'''.

|-
|| 06:36
|| '''start''' attribute specifies the initial value of a '''variable'''.

|-
|| 06:41
||The initial value of '''h''' is 30 units.

|-
|| 06:45
|| '''unit attribute''' specifies the unit of a '''variable'''.

|-
|| 06:49
||The unit of '''h''' is '''metre'''.

|-
|| 06:52
|| Every '''variable declaration''' must end with a '''semi-colon.'''

|-
||06:57
|| '''v''' represents '''velocity''' of ball. It is of '''Real data-type.'''

|-
|| 07:02
|| The initial value of '''v''' is zero. Its unit is '''meter per second.'''

|-
|| 07:09
|| '''g'''represents '''acceleration due to gravity'''. It is of '''Real data-type.''' And its unit is '''meter per second square.'''

|-
|| 07:18
|| '''parameter''' is a quantity that remains constant in a simulation run.

|-
|| 07:24
|| The value of '''g''' remains constant throughout the simulation run, with a value of 9.81.

|-
|| 07:32
||The negative sign is due to sign convention used.

|-
|| 07:36
|| The text in double quotes is a '''comment''' written with the declaration of '''g'''.

|-
|| 07:42
||'''Comments '''provide useful information about the program. They are also useful for documentation.

|-
|| 07:49
|| Now, let me go back to the slides.

|-
|| 07:52
|| '''parameter''' is a quantity that remains constant in a simulation run.

|-
|| 07:57
||'''Real, Integer, Boolean''' and''' String data-types''' are supported in '''Modelica'''.

|-
||08:03
||'''start''' and '''unit attributes''' have already been defined.

|-
|| 08:07
||'''min attribute''' specifies the minimum value of a '''variable'''.

|-
|| 08:10
||Similarly, '''max attribute''' specifies the maximum value of a '''variable'''.

|-
|| 08:16
|| Let me go back to '''OMEdit.'''

|-
|| 08:19
|| '''‘equation’ '''signifies the beginning of '''equation section''' of a '''class'''.

|-
|| 08:25
|| This is an alternative way of inserting '''comments'''.

|-
|| 08:30
|| The two '''equations of motion''' for a freely falling body, as we have already discussed, have been included here.

|-
|| 08:38
|| '''der()''' is '''Modelica function''' for '''time derivative'''.

|-
|| 08:43
||Hence, '''der(h)''' represents '''dh/dt.'''

|-
|| 08:48
|| And '''der(v)''' represents '''dv/dt.'''

|-
|| 08:52
|| Every '''equation''' must end with a '''semi-colon'''.

|-
|| 08:57
|| Let me show you how to simulate this '''class'''.

|-
|| 09:00
||Click on '''simulate''' button in the '''toolbar'''.

|-
|| 09:04
|| Close the pop-up window.

|-
|| 09:07
|| This window is known as the '''Plotting perspective'''.

|-
|| 09:11
||On successful simulation of a '''class, Plotting perspective''' opens automatically.

|-
|| 09:17
|| '''Variables browser''' displays information related to '''variables''' and '''parameters''' of a '''class'''.

|-
||09:24
||Note that there are columns named '''Unit''' and '''Description'''.

|-
|| 09:29
||'''Unit''' column specifies '''units''' of '''variables,''' as defined using '''Unit''' attribute.

|-
||09:37
||'''Description''' column displays '''comments''' written in double quotes with '''variable declarations'''.

|-
|| 09:45
|| Let me show you how to generate a '''plot'''. Select '''h'''.

|-
||09:51
||This generates the plot of '''h with respect to time''' -with '''h''' on '''y-axis''' and '''time''' on the '''x-axis'''

|-
||10:01
||By default, the simulation is run from 0 to 1 unit of time.

|-
|| 10:07
||The unit of '''time''' depends on the system of '''units''' used for other variables.

|-
|| 10:13
|| Let me de-select '''h.'''

|-
||10:17
||It is always a good practice to delete the results, once the necessary plots have been generated.

|-
||10:25
||To delete this result, right-click on '''freeFall''' and select '''Delete result'''.

|-
|| 10:33
||The result has now been deleted.

|-
|| 10:36
|| Let me go back to '''Modeling perspective'''.

|-
|| 10:39
||Click on '''Modeling''' button at bottom-right.

|-
||10:43
|| '''class''' is used synonymously with '''model,''' in '''Modelica'''.

|-
|| 10:48
||One may use '''model''' instead of '''class''' here, to produce the same effect.

|-
|| 10:54
|| Now, let me show you how to change the '''time interval''' for simulation.

|-
||11:01
||Click on '''Simulation Setup''' button present in the '''toolbar'''.

|-
|| 11:06
|| Under '''General''' tab, locate '''Stop time''' field. Change it to 5 units.

|-
||11:14
||Click on '''Simulate'''. Close the pop-up window which appears.

|-
|| 11:21
|| Let me select '''h''' once again, in the '''Variables browser'''.

|-
|| 11:26
||This generates '''h''' v/s '''time''' plot.

|-
||11:29
||Notice that the time interval has increased to 5 units.

|-
|| 11:33
||But, the value of '''h''' has gone below zero, which is unacceptable.

|-
||11:40
||We will learn how to rectify this issue in the later tutorials.

|-
||11:45
||Let me delete this result by right-clicking on '''freeFall''' and selecting '''Delete result'''.

|-
|| 11:53
|| Go back to '''Modeling''' perspective by clicking on '''Modeling perspective''' at bottom-right.

|-
||11:59
|| It is necessary to ensure that the number of equations is equal to the number of variables.

|-
|| 12:07
||This '''class''' has two variables and two equations.

|-
|| 12:11
||Now, let me delete the first '''equation''' and simulate this '''class''', to see what happens.

|-
||12:18
|| I have deleted the first '''equation'''.

|-
|| 12:21
||Notice that a star appears beside the name of the '''class''' in '''freeFall''' tab.

|-
|| 12:28
||This indicates unsaved changes in the '''class'''.

|-
|| 12:31
||Hence it is a good practice to save a '''class''' after a change has been made.

|-
||12:38
||To save this '''class, ''' go to the '''File menu''' and click on '''Save'''.

|-
|| 12:44
||You may also use the '''Save''' button in '''toolbar''', which my cursor points to, to save a file.

|-
||12:53
||Now, let me simulate this '''class''' by clicking on '''Simulate''' button.

|-
|| 12:59
|| Note that an error message pops up in the '''Messages browser'''.

|-
|| 13:04
||It says, there are too few equations and the model has 1 '''equation''' and 2 '''variables'''. Hence this cannot be simulated.

|-
|| 13:14
|| Let me insert the '''equation''' back in its place and click on '''Save''' button in the '''toolbar'''.

|-
||13:24
||Click on '''Simulate''' button once again to simulate this '''class'''.

|-
|| 13:29
||Note that the '''class''' simulates successfully, since the number of '''equations''' is equal to the number of '''variables'''.

|-
||13:37
||Close the pop-up window.

|-
|| 13:40
|| Let me go back to the slides.

|-
|| 13:43
|| '''“der()”''' is '''Modelica''' function for '''time derivative'''.

|-
|| 13:48
||There is no data flow direction for '''equations'''.

|-
|| 13:52
||For example, '''der(h) = v''' may also be written as '''v = der(h)'''.

|-
|| 14:00
||'''Initial equations section''' is used to enter initial conditions.

|-
|| 14:05
||We shall learn more about '''Initial equation''' later on.

|-
|| 14:10
|| As an assignment, write a '''model''' to simulate the '''differential equation''' '''dx/dt = -a into x ''' , where '''a = 1''', '''x''' belongs to '''R''' and the value of x at time '''t=0''' is '''5'''

|-
|| 14:28
|| This brings us to the end of this tutorial.

|-
|| 14:31
|| Watch the video at the following link. It summarizes the Spoken Tutorial project.

|-
|| 14:37
|| We conduct workshops using spoken tutorials; give certificates. Please contact us.

|-
|| 14:43
|| '''Spoken Tutorial project''' is funded by NMEICT, MHRD, Government of India.

|-
|| 14:49
|| We thank the development team of '''OpenModelica''' for their support.

|-
|| 14:53
|| Thank you.
|-
|}

@@ Line 315: / Line 315: @@
 |-
 || 06:52
-|| Every variable declaration''' must end with a semi-colon.
+|| Every variable declaration  must end with a semi-colon.
 |-

@@ Line 95: / Line 95: @@
 |-
 || 02:23
-|| click on''' ‘Modeling''' perspective’.
+|| click on''' ‘Modeling’''' perspective.
 |-
 ||02:26
-||'''‘Modeling''' perspective’ has now opened.
+||'''‘Modeling’''' perspective has now opened.
 |-
@@ Line 111: / Line 111: @@
 |-
 || 02:51
-||We will learn more about these buttons, as we go along.
+||We will learn more about these buttons as we go along.
 |-
@@ Line 143: / Line 143: @@
 |-
 || 03:39
-||'''Libraries Browser''' shows all '''classes''' that are loaded in a session of '''OMEdit'''.
+||'''Libraries Browser''' shows all '''classes''' that are '''load'''ed in a session of '''OMEdit'''.
 |-
@@ Line 203: / Line 203: @@
 |-
 ||04:43
-|| A dialog box pops up, as shown.
+|| A dialog box pops up as shown.
 |-
 || 04:46
-||In the '''Name''' field of this dialog box, type '''freeFall'''.
+||In the '''Name''' field of this dialog box, type: '''freeFall'''.
 |-
@@ Line 231: / Line 231: @@
 |-
 ||05:20
-||Let me delete '''annotation section'''.
+||Let me delete '''annotation''' section.
 |-
 || 05:23
-|| Now, you may type the required information here and save this '''class'''.
+|| Now, you may type the required information here and '''save''' this '''class'''.
 |-
@@ Line 243: / Line 243: @@
 |-
 || 05:36
-|| Choose an appropriate location for this file and save it.
+|| Choose an appropriate location for this file and '''save''' it.
 |-
@@ Line 251: / Line 251: @@
 |-
 || 05:47
-||So switch to '''freeFall class'''.
+||So, switch to '''freeFall''' class.
 |-
@@ Line 271: / Line 271: @@
 |-
 || 06:05
-|| Every '''class''' must have an '''end statement''' to indicate where the '''class''' ends.
+|| Every '''class''' must have an '''end''' statement to indicate where the '''class''' ends.
 |-
 || 06:11
-|| This '''class '''has '''variable declarations '''and '''equations'''.
+|| This '''class '''has '''variable declarations '''and equations.
 |-

@@ Line 5: / Line 5: @@
 |-
 ||00:01
-||Welcome to the spoken tutorial on '''Developing an equation based model'''.
+||Welcome to the '''spoken tutorial''' on '''Developing an equation based model'''.
 |-
 || 00:06
-|| In this tutorial, we are going to learn: How to create a textual model in '''OMEdit''' and simulate it.
+|| In this tutorial, we are going to learn:
 |-
 || 00:14
-||How to declare variables and equations.
+||how to declare '''variable'''s and equations,
 |-
 || 00:17
-||How to use '''Simulation Setup''' toolbox.
+||how to use '''Simulation Setup''' toolbox.
 |-
 || 00:21
-|| To record this tutorial, I am using  '''OpenModelica 1.9.2 ''' and '''Ubuntu Linux Operating System 14.04'''
+|| To record this tutorial, I am using  '''OpenModelica 1.9.2 ''' and '''Ubuntu Linux Operating System 14.04'''.
 |-
@@ Line 33: / Line 34: @@
 |-
 || 00:48
-|| Let us simulate the motion of a ball of mass ''''m'''', which is under '''free fall due to gravity'''.
+|| Let us simulate the motion of a ball of mass ''''m'''' which is under free fall due to gravity.
 |-
@@ Line 49: / Line 50: @@
 |-
 || 01:10
-||Variables directed away from the surface of Earth, are considered positive.
+||Variables directed away from the surface of earth are considered positive.
 |-
 || 01:16
-|| The '''equations of motion''' for a freely falling body, are as follows:'''dh/dt = v'''  ,  '''dv/dt = g'''
+|| The equations of motion for a freely falling body are as follows:
 |-
 || 01:27
-||The value of '''h''' at time '''t = 0''' is '''30''' m and the value of '''v''' at time '''t = 0''' is '''0'''.
+||The value of '''h''' at time '''t = 0''' is '''30''' meters and the value of '''v''' at time '''t = 0''' is '''0'''.
 |-
 || 01:37
-|| Now let me go to '''OMEdit'''. I have already launched it on my system.
+|| Now, let me go to '''OMEdit'''. I have already launched it on my system.
 |-
 ||01:43
-|| To open '''OMEdit '''on '''Ubuntu Linux Operating System''', click on '''Dash Home '''icon, which appears at the top left, in '''launcher'''.
+|| To open '''OMEdit '''on '''Ubuntu Linux Operating System''', click on '''Dash Home '''icon which appears at the top left, in '''launcher'''.
 |-
@@ Line 77: / Line 79: @@
 |-
 ||01:59
-||On clicking '''OMEdit''' icon, you see a window such as this.
+||On clicking '''OMEdit''' icon, you see a '''window''' such as this.
 |-
@@ Line 85: / Line 87: @@
 |-
 || 02:09
-||'''OMEdit''' by default, opens in the '''"Welcome perspective"'''
+||'''OMEdit''' by default, opens in the '''"Welcome perspective"'''.
 |-
 || 02:14
-|| At the bottom right-hand corner, you can locate buttons for '''‘Welcome’, ‘Modeling’''' and '''‘Plotting’ perspectives'''.
+|| At the bottom right-hand corner, you can locate buttons for '''‘Welcome’, ‘Modeling’''' and '''‘Plotting’''' perspectives.
 |-
 || 02:23
-|| click on''' ‘Modeling perspective’'''.
+|| click on''' ‘Modeling''' perspective’.
 |-
 ||02:26
-||'''‘Modeling perspective’''' has now opened.
+||'''‘Modeling''' perspective’ has now opened.
 |-
@@ Line 117: / Line 119: @@
 |-
 || 03:02
-||Please download this file and save it on your system.
+||Please download this file and '''save''' it on your system.
 |-
@@ Line 133: / Line 135: @@
 |-
 || 03:24
-|| You may also use the tool named '''Open Model/Library File''', that my cursor is pointing to, for opening a file.
+|| You may also use the tool named '''Open Model/Library File''' that my cursor is pointing to, for opening a file.
 |-