View source for OpenModelica/C3/Block-Component-Modeling/English-timed

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

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|| 00:01
|| Welcome to the spoken tutorial on '''Block component modeling'''.

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|| 00:06
|| In this tutorial, we are going to learn: How to define a '''block'''.

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|| 00:12
||How to connect '''blocks'''.

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|| 00:15
||How to use blocks from '''Modelica Library'''.

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|| 00:19
|| To record this tutorial, I am using:  '''OpenModelica version 1.9.2'''

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|| 00:26
||You may use any of the following operating systems.

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|| 00:30
|| To understand and practice this tutorial, you need Knowledge of '''component oriented modeling''' in '''Modelica'''.

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|| 00:38
|| Prerequisite tutorials are mentioned on our website. Please go through them.

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||00:44
|| Let us now learn more about '''blocks'''.

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||00:48
|| '''block''' is a specialized class in '''Modelica'''.

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||00:52
|| It is useful in control applications. 

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||00:56
||For example, '''Modelica Library''' has blocks for '''PI''' and '''PID''' controllers which are frequently seen in chemical engineering control applications.
 
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||01:08
||variables of a block class must have fixed causality: either '''input''' or '''output'''.

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||01:15
|| '''blocks''' can be connected using '''connect''' statements.
 
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||01:19
||We have learnt about '''connect''' statements in previous tutorials.

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|| 01:24
|| '''Connectors''' acts as interface between '''blocks'''.

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||01:28
||They are used to model '''input''' and '''output''' signals.

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||01:33
||For example, this is declaration for a '''block connector''' that models '''real''' input signals.

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||01:41
|| Let us now try to understand '''block component modeling''' through an example. 

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||01:47
||Let us write a class that uses blocks to perform the following operations: Take two time varying signals as '''input''' and '''output''' their sum.
 
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||01:59
||Take a time varying signal as input and amplify it by a constant.

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||02:05
||Let us define this problem statement in detail using schematics.

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|| 02:11
|| This figure shows a schematic for block that takes two signals as input and returns their sum. 

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||02:19
||To make things simpler, let us choose signal '''1''' to be '''t''' which represents time. 

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||02:26
||Let signal '''2''' be '''2 (times) t (squared)'''

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|| 02:31
|| This is schematic for amplification of a '''signal'''. 

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||02:35
||It is similar to the previous case with two '''inputs''' and one '''output'''. 

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||02:41
||Let us choose one '''input''' to be our '''signal'''. 

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||02:46
||Let the other '''input''' i.e. '''signal 2''' be a constant '''K''' by which to amplify the signal. 

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||02:54
||The product of these two '''inputs''' is the '''output''' required. 

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||02:59
||We have chosen the '''signal 2''' i.e. '''K''' to be '''5''' units.

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|| 03:06
|| Notice that both the Sum of signals and amplification require a block with '''2''' inputs and '''1''' output.

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||03:16
||'''Modelica library''' already has a block named '''MISO''' that stands for '''Multiple Input Single Output'''. 

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||03:24
||It is available in '''Modelica.Interfaces.Block''' package.

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||03:30
||The input to this block '''u''' is a vector since it can accept multiple signals as input. 

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||03:38
||'''y''' is the output which is a '''scalar'''.

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|| 03:42
|| Let us now discuss how to solve our problem using '''OMEdit'''.

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||03:48
||Extend '''MISO''' block to create a block named '''Sum'''. 

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||03:53
||We have learnt about extending a class in previous tutorials.

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||03:59
||Extend '''MISO''' to create a block named '''Product'''.

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||04:04
||Create a class named '''main'''.

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||04:08
||Create instances of '''Sum''' and '''Product''' blocks in the '''main''' class.

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||04:14
||Lastly, program the necessary equations related to '''input''' and '''output''' variables. 

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||04:22
||Note that '''Sum''' corresponds to the Sum of signals whereas '''Product''' corresponds to the '''amplification of signal'''.

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|| 04:32
|| I have already created the necessary '''blocks '''and packaged them into a file named '''arithmeticOperationsUsingBlocks'''. 

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||04:42
||You may locate this file on our website and download it. 

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|| 04:46
|| Let me now switch to '''OMEdit'''.

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||04:49
||I shall first demonstrate the package '''arithmeticOperationsUsingBlocks''' and then demonstrate the syntax of '''MISO''' block. 

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|| 04:59
|| I have already opened the package '''arithmeticOperationsUsingBlocks''' in '''OMEdit'''. 

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||05:06
||Let me expand it in the '''Libraries Browser'''. 

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||05:10
||Note that the package has blocks named '''Sum''', '''Product''' and a '''main''' class.

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|| 05:18
|| Double-click on all three of them. 

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||05:24
||Let me also open '''MISO''' block from '''Modelica Library'''. 

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|| 05:29
|| Expand '''Modelica library'''. 

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||05:32
||Go to '''Blocks → Interfaces'''.  Scroll down a bit. 

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||05:39
||Double Click on '''MISO'''.

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||05:43
||Interfaces package also has several other blocks which are similar to '''MISO''' in functionality. 

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|| 05:51
|| Now let me shift '''OMEdit''' window to the left for better visibility. 

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||05:57
||Let us first look into '''Sum''' block.

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|| 06:01
|| Switch to '''Text View''' if it opens in '''Diagram View'''.

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|| 06:05
|| This is the syntax for declaring a '''block'''.

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|| 06:10
|| This statement is used to inherit '''MISO block''' from its location in '''Modelica library'''. 

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||06:16
||We have learnt about '''Class inheritance''' or '''Class extension''' in previous tutorials.

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|| 06:23
|| Let me now take a step back for a moment and demonstrate '''MISO block'''. 

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||06:29
||Go to '''MISO tab'''.  Switch to '''Text View'''.

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|| 06:35
|| '''MISO''' is a partial block which means that it can only be inherited but not instantiated.

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|| 06:43
|| It inherits '''Block class'''. 

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||06:46
||You may locate this in '''Modelica library''' using the path shown. 

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||06:51
||This class is used here only for the sake of its '''Diagram View''' and hence need not be discussed.

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||06:58
|| '''nin''' represents the number of inputs. 

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||07:02
|| This parameter may be changed when the block is inherited.

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|| 07:08
|| '''RealInput''' is a connector which evidently represents a '''real''' input signal. 

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||07:14
||In this case, the input is a vector '''u''' as we already discussed.

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|| 07:20
|| Similarly, '''RealOutput''' is a connector which represents a '''real''' output signal. 

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||07:27
||Here, '''y''' is the real-valued output signal. 

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|| 07:31
|| '''RealInput''' and '''RealOutput''' are present in the same package of '''Modelica Library''' as '''MISO'''. 

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||07:38
||Please look into them.

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|| 07:41
|| Now, let me show you how the '''Diagram View''' of '''MISO block''' looks like.

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|| 07:46
|| Let us now go back to '''Sum''' block and continue from where we left off.

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|| 07:52
|| Variables '''y''' and '''u''' are a part of this block since it inherits '''MISO'''. 

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||07:59
||As we have learnt in previous tutorials, '''Sum''' is an '''array''' function.

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||08:05
||It takes an '''array''' as input and returns the sum of its elements.

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|| 08:11
|| Let me switch to '''Product''' block. Switch to '''Text View'''.

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|| 08:17
|| This block inherits '''MISO''' as well.

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|| 08:21
|| As we have seen in previous tutorials, '''Product''' is an array function that takes an array as '''input'''. 

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||08:29
||It returns the product of its elements.

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|| 08:33
|| Let me now switch to '''main''' class. 

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||08:37
||Switch to '''Text View'''. 

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||08:39
|| These statements indicate the instantiation of '''Sum''' and '''Product''' blocks. 

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||08:44
||These instances can also be created using the drag and drop functionality of '''OMEdit'''.

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||08:51
||We discussed this feature in previous tutorials.

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|| 08:56
|| '''nin''' is a parameter for dimension of '''input''' vector '''u''' in '''MISO'''. 

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||09:03
||We assign a value of '''2''' to this parameter.

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||09:07
|| This equation indicates the values of '''signal 1''' and '''signal 2''' for '''Sum''' of signals which we discussed in slides.

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|| 09:17
|| Similarly, this indicates the values of '''Signal 1''' and '''Signal 2''' for amplification of signal as we already discussed.

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|| 09:29
|| Let me now simulate this class.  Click on '''Simulate''' button.

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||09:33
||Close the pop up window.

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|| 09:36
|| Expand '''mySum''' in '''Libraries Browser'''. Select '''y'''. 

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||09:43
||Note that this generates a plot that is in accordance with the values of signal provided.

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|| 09:51
|| This brings us to the end of this tutorial. 

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|| 09:54
|| As an assignment, look into the codes for '''RealInput, RealOutput, SI, SO''' and '''MO''' blocks. 

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||10:04
||You can find them in '''Modelica.Blocks.Interfaces''' package.

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||10:10
||'''RealInput'''and '''RealOutput''' are connectors which are used quite frequently.

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||10:17
||Hence it is necessary to understand them.

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|| 10:21
|| Watch the video available at the following link: http://spoken-tutorial.org/What\_is\_a\_Spoken\_Tutorial .It summarises the '''Spoken Tutorial''' project.

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|| 10:27
|| We conducts workshops using '''spoken tutorials'''. Give certificates. Please contact us.

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|| 10:33
|| If you have questions in this spoken tutorial, please visit the webpage mentioned.

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|| 10:40
|| We coordinate coding of solved examples from popular books.  We give honorarium to contributors. Please visit our website.

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|| 10:50
|| We help migrate labs from commercial simulators to '''OpenModelica'''.

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|| 10:56
|| '''Spoken Tutorial Project''' is supported by '''NMEICT, MHRD''', Government of India.

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|| 11:03
|| We thank the development team of '''OpenModelica''' for their support.

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|| 11:09
|| I would like to thank you for joining me in this tutorial. Good bye.