OpenModelica/C3/Block-Component-Modeling/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Block component modeling.
00:06	In this tutorial, we are going to learn: how to define a block,
00:12	how to connect blocks,
00:15	how to use blocks from Modelica Library.
00:19	To record this tutorial, I am using: OpenModelica version 1.9.2
00:26	You may use any of the following operating systems.
00:30	To understand and practice this tutorial, you need knowledge of component oriented modeling in Modelica.
00:38	Prerequisite tutorials are mentioned on our website. Please go through them.
00:44	Let us now learn more about blocks.
00:48	block is a specialized class in Modelica.
00:52	It is useful in control applications.
00:56	For example, Modelica Library has blocks for PI and PID controllers which are frequently seen in chemical engineering control applications.
01:08	Variables of a block class must have fixed causality, either input or output.
01:15	blocks can be connected using connect statements.
01:19	We have learnt about connect statements in previous tutorials.
01:24	Connectors acts as interface between blocks.
01:28	They are used to model input and output signals.
01:33	For example, this is declaration for a block connector that models real input signals.
01:41	Let us now try to understand block component modeling through an example.
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.
01:59	Take a time varying signal as input and amplify it by a constant.
02:05	Let us define this problem statement in detail using schematics.
02:11	This figure shows a schematic for block that takes two signals as input and returns their sum.
02:19	To make things simpler, let us choose signal 1 to be t which represents time.
02:26	Let signal 2 be 2 times t squared.
02:31	This is schematic for amplification of a signal.
02:35	It is similar to the previous case with two inputs and one output.
02:41	Let us choose one input to be our signal.
02:46	Let the other input i.e. signal 2 be a constant K by which to amplify the signal.
02:54	The product of these two inputs is the output required.
02:59	We have chosen the signal 2 i.e. K to be 5 units.
03:06	Notice that both the sum of signals and amplification require a block with 2 inputs and 1 output.
03:16	Modelica library already has a block named MISO that stands for Multiple Input Single Output.
03:24	It is available in Modelica.Interfaces.Block package.
03:30	The input to this block u is a vector since it can accept multiple signals as input.
03:38	y is the output which is a scalar.
03:42	Let us now discuss how to solve our problem using OMEdit.
03:48	Extend MISO block to create a block named Sum.
03:53	We have learnt about extending a class in previous tutorials.
03:59	Extend MISO to create a block named Product.
04:04	Create a class named main.
04:08	Create instances of Sum and Product blocks in the main class.
04:14	Lastly, program the necessary equations related to input and output variables.
04:22	Note that Sum corresponds to the Sum of signals whereas Product corresponds to the amplification of signal.
04:32	I have already created the necessary blocks and packaged them into a file named arithmeticOperationsUsingBlocks.
04:42	You may locate this file on our website and download it.
04:46	Let me now switch to OMEdit.
04:49	I shall first demonstrate the package arithmeticOperationsUsingBlocks and then demonstrate the syntax of MISO block.
04:59	I have already opened the package arithmeticOperationsUsingBlocks in OMEdit.
05:06	Let me expand it in the Libraries Browser.
05:10	Note that the package has blocks named Sum, Product and a main class.
05:18	Double-click on all three of them.
05:24	Let me also open MISO block from Modelica Library.
05:29	Expand Modelica library.
05:32	Go to Blocks → Interfaces. Scroll down a bit.
C5:39	Double click on MISO.
05:43	Interfaces package also has several other blocks which are similar to MISO in functionality.
05:51	Now, let me shift OMEdit window to the left for better visibility.
05:57	Let us first look into Sum block.
06:01	Switch to Text View if it opens in Diagram View.
06:05	This is the syntax for declaring a block.
06:10	This statement is used to inherit MISO block from its location in Modelica library.
06:16	We have learnt about Class inheritance or Class extension in previous tutorials.
06:23	Let me now take a step back for a moment and demonstrate MISO block.
06:29	Go to MISO tab. Switch to Text View.
06:35	MISO is a partial block which means that it can only be inherited but not instantiated.
06:43	It inherits Block class.
06:46	You may locate this in Modelica library using the path shown.
06:51	This class is used here only for the sake of its Diagram View and hence need not be discussed.
06:58	nin represents the number of inputs.
07:02	This parameter may be changed when the block is inherited.
07:08	RealInput is a connector which evidently represents a real input signal.
07:14	In this case, the input is a vector u as we already discussed.
07:20	Similarly, RealOutput is a connector which represents a real output signal.
07:27	Here, y is the real-valued output signal.
07:31	RealInput and RealOutput are present in the same package of Modelica Library as MISO.
07:38	Please look into them.
07:41	Now, let me show you how the Diagram View of MISO block looks like.
07:46	Let us now go back to Sum block and continue from where we left off.
07:52	Variables y and u are a part of this block since it inherits MISO.
07:59	As we have learnt in previous tutorials, Sum is an array function.
08:05	It takes an array as input and returns the sum of its elements.
08:11	Let me switch to Product block. Switch to Text View.
08:17	This block inherits MISO as well.
08:21	As we have seen in previous tutorials, Product is an array function that takes an array as input.
08:29	It returns the product of its elements.
08:33	Let me now switch to main class.
08:37	Switch to Text View.
08:39	These statements indicate the instantiation of Sum and Product blocks.
08:44	These instances can also be created using the drag and drop functionality of OMEdit.
08:51	We discussed this feature in previous tutorials.
08:56	nin is a parameter for dimension of input vector u in MISO.
09:03	We assign a value of 2 to this parameter.
09:07	This equation indicates the values of signal 1 and signal 2 for Sum of signals which we discussed in slides.
09:17	Similarly, this indicates the values of Signal 1 and Signal 2 for amplification of signal as we already discussed.
09:29	Let me now simulate this class. Click on Simulate button.
09:33	Close the pop-up window.
09:36	Expand mySum in Libraries Browser. Select y.
09:43	Note that this generates a plot that is in accordance with the values of signal provided.
09:51	This brings us to the end of this tutorial.
09:54	As an assignment, look into the codes for RealInput, RealOutput, SI, SO and MIMO blocks.
10:04	You can find them in Modelica.Blocks.Interfaces package.
10:10	RealInputand RealOutput are connectors which are used quite frequently.
10:17	Hence it is necessary to understand them.
10:21	Watch the video available at the following link: http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarizes the Spoken Tutorial project.
10:27	We conduct workshops using spoken tutorials, give certificates. Please contact us.
10:33	If you have questions in this spoken tutorial, please visit the webpage mentioned.
10:40	We coordinate coding of solved examples from popular books. We give honorarium to contributors. Please visit our website.
10:50	We help migrate labs from commercial simulators to OpenModelica.
10:56	Spoken Tutorial Project is supported by NMEICT, MHRD, Government of India.
11:03	We thank the development team of OpenModelica for their support.
11:09	I would like to thank you for joining me in this tutorial. Good bye.

Contributors and Content Editors

Jyotisolanki, Priyacst, Sandhya.np14