OpenModelica/C3/Component-oriented-modeling/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to the spoken tutorial on Component oriented modeling. |
| 00:06 | In this tutorial, we are going to learn:
how to instantiate a model, |
| 00:12 | how to define connector class and
how to develop model of a simple electric circuit using component models. |
| 00:21 | To record this tutorial, I am using: OpenModelica 1.9.2, Ubuntu Operating System version 14.04. |
| 00:31 | But this process is identical to any of the following operating systems. |
| 00:39 | To understand and practice this tutorial, you need to know how to define a class in Modelica. |
| 00:45 | You need to know how to define a package and Icon and Diagram Views. |
| 00:51 | Prerequisite tutorials are mentioned on our website. Please go through them. |
| 00:57 | Now let us learn more about Class Instantiation. |
| 01:02 | Modelica classes can be instantiated. |
| 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. |
| 01:20 | The syntax for Class Instantiation is as shown. |
| 01:25 | Now, let us understand this through an example. Please download and save all the files available on our website. |
| 01:34 | Let me switch to OMEdit. The following files are already open in OMEdit: classInstantiationExample and simpleCircuit. |
| 01:48 | Double-click on classInstantiationExample. Let us discuss more about this class now. |
| 01:56 | Let me shift OMEdit window to the left for better visibility. |
| 02:02 | Here, I have instantiated the bouncingBall class to create two objects named object1 and object2. |
| 02:12 | Note that each instance has different start values for the height variable h. |
| 02:20 | Please refer prerequisite tutorials for more information on the bouncingBall model. |
| 02:27 | Let us simulate this class now. |
| 02:30 | Click on Simulate button in the toolbar. |
| 02:34 | The class did not simulate and it threw up an error. |
| 02:39 | This is because bouncingBall class is not open in OMEdit. |
| 02:45 | Open bouncingBall class which you downloaded from the website. |
| 02:50 | Now, simulate this class once again. Close the pop-up window. |
| 02:56 | Note that the class simulates successfully this time around. |
| 03:01 | This exercise demonstrates that a class should be open in OMEdit to be instantiated. |
| 03:09 | Expand object1 variables in the variables browser. |
| 03:14 | Note that the variables listed here are declared in bouncingBall class. |
| 03:20 | These variables are also a part of object1 and object2 since they are just instances of the bouncingBall class. |
| 03:30 | Now, delete the result and go back to the slides. |
| 03:37 | Component orientation sets Modelica apart from other modeling and simulation softwares. |
| 03:43 | It is the single most important feature of Modelica. |
| 03:48 | component models represent single physical phenomenon. |
| 03:53 | They can be instantiated and connected to produce desired effect. |
| 03:59 | For example, an RLC circuit could be developed from resistor, inductor and capacitor models. |
| 04:08 | Acausal connectors serve as the interface between component instances. |
| 04:15 | They are defined using connector class. For example, pins can be used as connectors for electrical components. |
| 04:24 | We will learn more about this when we try to simulate the example for an electric circuit. |
| 04:30 | Connectors contain across and flow variables and they cannot contain equations. |
| 04:38 | Now, let us simulate this Electric Circuit shown in the slide. |
| 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. |
| 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. |
| 05:14 | Hence, define a connector named pin. |
| 05:18 | Define a class named Ground with one instance of pin connector. |
| 05:24 | Define a class named Resistor. |
| 05:28 | The Resistor class should have two instances of the pin connector: Positive pin and the Negative pin. |
| 05:36 | Define a class named VoltageSource with two instances of pin connector as we have seen in the case of resistor class. |
| 05:46 | Define a class named simpleCircuit. simpleCircuit should have instances of Resistor and VoltageSource. |
| 05:56 | Connect the respective pins of Resistor, ground and the VoltageSource. |
| 06:02 | The component models required have already been programmed. |
| 06:07 | Hence, I shall demonstrate only the last two steps of Solution Methodology. |
| 06:13 | Let me switch to OMEdit. Go back to the Modeling perspective. |
| 06:19 | Let me shift OMEdit window to the right. |
| 06:23 | Expand simpleElectricCircuitpackage in the Libraries Browser. |
| 06:29 | Note that this package has five classes named: pin, Ground, Resistor, Voltage Source and circuit. |
| 06:40 | Double-click on simpleElectricCircuit. Close ClassinstantiationExample. |
| 06:48 | Let me shift OMEdit window to the left once again, for better visibility. |
| 06:54 | Modelica.SIunits package has been imported in the package simpleElectricCircuit. |
| 07:02 | Hence, type definitions in that package can be used without reference to their full names. |
| 07:10 | Let us try to understand pin connector. Scroll-down a little bit. |
| 07:17 | Pin is defined using connector class. |
| 07:21 | Voltage and current are the variables that a pin exchanges with its surroundings. |
| 07:27 | Potential at the pin is defined by v. Voltage and Current are types defined in SIunits package of Modelica library. |
| 07:40 | Voltage across a component causes a current to flow through it. |
| 07:44 | Hence, current is a flow variable and is defined using flow keyword. |
| 07:50 | pin connector also has an Icon view specified by annotations as shown. |
| 07:57 | Now, let us discuss a little about Resistor class. Scroll down a little more. |
| 08:04 | As discussed in the Solution Methodology, Resistor class has two instances of pin connector. |
| 08:12 | p stands for positive pin and n stands for negative pin. |
| 08:18 | Now, let me show you how to instantiate a class using the drag and drop functionality of OMEdit. |
| 08:26 | To demonstrate that, let me open a new class using Ctrl + N. |
| 08:32 | Name this class example1 and press Ok. Shift OMEdit window to the right. |
| 08:41 | Go to Diagram View if the class opens in Text View. |
| 08:46 | Now, let me instantiate pin class. |
| 08:51 | Left-click on pin icon in Libraries Browser. |
| 08:55 | Hold and drag the icon to the diagram layer. Drop it at any location on the canvas. |
| 09:04 | We have now created an instance of pin class. |
| 09:09 | You may also change the dimensions and location after dropping it, as shown. |
| 09:16 | Now, let us see how this class is instantiated in Text View. Go to Text View. |
| 09:22 | Notice the command for instantiation of class pin and an annotation based on its placement in Diagram View. |
| 09:33 | Hence, creating an instance of a class in Diagram View automatically reflects in the Text View. Now, let me close example1 tab. |
| 09:45 | Let us learn how to model electric circuit that we saw in the slides. |
| 09:51 | Double-click on Circuit icon which is also a part of simpleElectricCircuit package. |
| 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. |
| 10:09 | But let us build the same circuit in a new file. |
| 10:14 | We shall use drag and drop functionality that we have just learnt about. |
| 10:19 | Press Ctrl + N. Name this file circuit(underscore)construction. Press OK. |
| 10:28 | Switch to Diagram View, if it opens in Text View. |
| 10:32 | Select, drag and drop the VoltageSource icon from Libraries Browser. You may change its dimensions as you wish. |
| 10:43 | Similarly, select, drag and drop the Resistor icon from Libraries Browser. |
| 10:50 | Do the same with Ground class. |
| 10:54 | Now, we need to connect the respective pins of each component. |
| 11:00 | Let us first connect the positive pin of Voltage Source to the positive pin of Resistor. |
| 11:07 | Hover over the left pin of Voltage Source. |
| 11:11 | The text that appears indicates that this is the positive pin p. |
| 11:17 | Left click on this pin and drag the cursor closer to the left pin of Resistor. |
| 11:24 | Leave the mouse when the appearance of cursor changes to cross from an arrow. |
| 11:30 | Similarly, connect the negative pin of resistor to the negative pin of voltage source. |
| 11:38 | We have not mentioned the connections with Ground in the circuit diagram. |
| 11:44 | But, we need to connect the negative pins of Resistor and Voltage Source to Ground individually. |
| 11:51 | This ensures a reference point for potential in the circuit. |
| 11:57 | Now, this class is complete. Save the class by pressing Ctrl + S. |
| 12:04 | Click on Simulate button. Close the pop -up window. |
| 12:10 | The class has simulated successfully. |
| 12:14 | Let me shift OMEdit window to the left, for better visibility of Variables browser. |
| 12:20 | Expand Resistor column in the Variables Browser and select Ir. |
| 12:28 | Note that the profile is sinusoidal as expected |
| 12:33 | since the Voltage Source is an AC source instead of DC. |
| 12:38 | Hence, we have created a model from its component parts and simulated it. |
| 12:44 | We shall learn more about the Resistor and Voltage Source classes that we used here in the next tutorial. |
| 12:52 | Let me switch to the slides. |
| 12:55 | This brings us to the end of this tutorial. |
| 12:59 | As an assignment, construct an electric circuit with two resistors in series with one Voltage Source. |
| 13:07 | Use the component models for Voltage source and Resistor provided in simple electric circuit package. |
| 13:15 | Watch the video available at the following link. It summarizes Spoken Tutorial project. |
| 13:21 | We conduct workshops using spoken tutorials. Please contact us. |
| 13:26 | If you have questions from this tutorial, please visit the website mentioned below. |
| 13:32 | We coordinate coding of solved examples of popular books. Please visit our website. |
| 13:38 | We help migrate commercial simulator labs to OpenModelica. Please visit the following website for more information. |
| 13:47 | Spoken Tutorial Project is funded by NMEICT, MHRD Government of India. |
| 13:54 | We thank the development team of OpenModelica for their support. Thank you. |
