MATLAB PROJECTS: Teaching Enhanced with Simulations in Simulink

Teaching Enhanced with Simulations in Simulink

Introduction – Teaching in University

In the engineering sphere, courses are usually commenced off with introduction of formulae or equations that describe underlying principles of various theories. These equations are then transformed from printed symbols on the blackboard to actual observed occurrences in real world systems (through experiments conducted in laboratory classes). This is the teaching method that has been practised for centuries and is widely believed to be the best method by lecturers.

However, this current teaching approach can still be improved. In reality, most students find it difficult to relate the theories they learnt to the real world systems they actually see.

Figure 1 – Missing Link between Theories learnt in lectures and the Real World Applications.

This is because there are many limitations to what can be achieved in the laboratory (e.g. safety, cost). Besides, experiments are not always easy to grasp the first time doing it nor it is as straightforward as it may thought to be. An intermediate stage between these two phases is needed to ease and speed up the transition. This intermediate stage will be discussed in the next section but before that let’s see how teaching has evolved over the century and why this intermediate phase is important in this modern world.

The Evolution of Teaching

Everything evolves over time, and so is teaching. Looking back, chalkboard art (Figure on the right) was the popular method used to teach a couple of decades ago. However, there are disadvantages with this method.

The teaching and learning process is slower.

Lecturers have to write the notes on the blackboard and students have to copy them down. This ’2 times’ writing process impedes capability for speedier transfer of knowledge.
Every diagram/graph/chart drawn is a sketch, not accurate, and static.

Though lecturers may be able to draw diagrams accurately but students often misinterpret the sketches and then get baffled with their notes later on. In addition, diagrams are static and inhibit students’ capability to learn faster through visualisations.

Explaining effects of a parameter change (in an equation) could be awful.

Frequently, lecturers want to explain the significance of parameters in an equation to illustrate the effects they have on the real system. To achieve this, lecturers have to erase and redraw the diagram all over again, which is time wasting and painful.

As time goes by, technology advances and then comes the projector art. With the overhead projector, lecturers improved their teaching considerably. Below is the list of advantages (and disadvantages) of projector art.

Cleaner

Chalks are replaced with ink pens and transparencies. No more dry fingers, dusters and asthma.
Eliminates inaccuracies

Projector technology enables lecturers to display photocopied transparencies during lectures. This enhances visual learning through display of accurate drawings/graphs/diagrams and students will be less likely to copy down incorrect diagrams.
Speedier learning

With photocopied transparencies, lecturers now reduce time wastage by eliminating the need to write lots of notes or draw diagrams on the blackboard. The transparencies can also be photocopied and be distributed to the students as notes.
(Disadvantage) Diagrams are still static

Though accurate, the diagrams/graphs/charts are still static (i.e. no animation or simulation). This is like comparing between staring at an image and watching a movie. We tend to experience and learn more in a movie (or a series of moving images).

Next in the evolution timeline is through the usage of simulations. Numerous researches have been conducted and visual learning has been found to be the easiest and quickest way to learn new information. Simulations are a very good method to enhance visual learning.

Simulation in Modern Teaching

Simulation plays a critical role in modern teaching. In this present era, technology advances at an unimaginable rate (compared to that half a century ago) and is constantly keeping us on our toes (in anticipation of ‘what’s new’ down the road). The amount of information is rising, the number of professionals is increasing and new researches are published every day. However, the number of years of education in a typical University degree remains the same (4 years). This means there is higher density of information that modern students need to absorb. This highlights an important trend that educators need to take note in order to keep up with intellect’s ever-expanding sphere. Let’s see an example of a conveyor mechanism.

Conveyor Mechanism (Figure on the right)

With chalkboard art, lecturers are limited to drawing sketches and writing equations on the blackboard. Describing kinematics or the actual operation of this mechanism takes a great deal of effort.

Projectors enhance the teaching process with the ability to display an accurate representation of the mechanism immediately and how various parts are connected together. (For e.g., just by photocopying the above model onto a transparency)

However, simulation enhances the teaching process considerably. Let’s take a look at the figures below.

The figures above illustrate a virtual conveyor mechanism built in the Simulink environment. Here are some of the advantages of this model.

With Simulink’s diverse features and capabilities, there is so much that can be achieved. A simple example shown here are the responses of the system (torque, linear and angular position) which are plotted as the simulation runs.
Students are able to directly view how the conveyor mechanism operates when (for e.g.) a certain amount of torque is applied to the lower link. These allow them to visualize the system and relate it directly to the equations they learnt in lectures.

Virtual model is safe, cheap and its parameters can be changed over and over again without any worries of unfortunate incidents. Students then can test and see for themselves (and learn) how the theories they learnt in lectures affect the behaviour of a system. Upon studying the system, then they can move on to the laboratory classes and relate what they discover in the simulation environment to the actual occurrences of real world systems.

(Though no simulations here) Simulations catch attention and build interests to those who see it. This increases students’ passion for the subject they studied and hence be able to always relate their studies to what they see.
Simulink allows lecturers to design models up to high level of complexity. Therefore, there’s almost no end to what can be designed in the Simulink environment and be shared during lectures. Simulink also enables students to link up with systems from other domains (e.g. electrical to mechanical to thermal) to test out the integration feasibility between systems.

Conclusion

In conclusion, as the phrase goes “Picture speaks a thousand words”, so is simulation in the teaching environment. With simulation, students are able to learn much more (through visual learning), as well as to understand the theories taught in lectures at a quicker rate. They’ll also be able to relate what was taught to the real engineering systems and hence increase their passion on the subject they’re learning.

End of the Article:

For more product information on Simulink, please refer to http://www.mathworks.com/products/simulink/?s_cid=global_nav

Article by James Ang, Application Engineer

Simulink for field-programmable gate array (FPGA) automation with Xilinx – Simple & Easy

MATLAB is renowned for algorithm exploration and development. On the other hand, Simulink is capable of performing time-based multi-domain system-level design, modelling, analysis, simulation in the graphical environment. Besides, Simulink also streamlines the development of embedded systems like FPGA and provides hardware verification or co-simulation of the user design, modelling and algorithm. With hardware co-simulation and deployment, we can obtain early customer feedback and confirmation.

Therefore, Mathworks has introduced EDA Simulator Link 3.3 with the ability of FPGA co-simulation via any of several Xilinx development boards in the Simulink environment. With EDA Simulator Link 3.3, we can:

Develop and implement our designs on FPGAs in days or weeks rather than in months.
Explore implementation and design trade-offs in hardware environment.
Verify HDL system level design.

Generally, the hardware co-simulation with Xilinx FPGA board is known as FPGA-in-the-loop (FIL). EDA Simulator Link supports FIL simulation on the devices shown in Table 1.

Device Family	Board
Spartan-6	Spartan-6 SP605 Spartan-6 SP601 XUP Atlys Spartan-6
Virtex-6	Virtex-6 ML605
Virtex-5	Virtex-5 ML505 Virtex-5 ML506 Virtex-5 ML507 Virtex-5 XUPV5–LX110T
Virtex-4	Virtex-4 ML401 Virtex-4 ML402 Virtex-4 ML403

Table 1: Support of Xilinx board in FIL simulation

FIL provides the capability to test our designs in real hardware for any existing HDL code (VHDL, Verilog). The HDL code can be either manually written or generated from Simulink HDL coder. FIL then performs the following process:

Generates a Simulink FIL block that represents the HDL code
Creates a programming file and loads the design onto an FPGA with JTAG connection
Receive and transmits data from Simulink to the FPGA via Ethernet connection
Verify the design in a real environment

The FIL process provides synthesis, logical mapping, PAR (place-and-route), programming file generation, and communications channel. All these capabilities are specifically designed for a particular Xilinx board.

Figure 1 demonstrates how EDA Simulator Link 3.3 communicates between Simulink and the FPGA board using FIL simulation.

Figure 1: FIL Simulation with Xilinx FPGA Board

For the purpose of better understanding of this newly introduced FIL, let’s explore the way on how the FIL works. From Figure 1, it is shown that the FIL co-simulation block (hdlduc) is the interface between the Simulink model and the executable application running on the Xilinx FPGA board. The hdlduc FIL Simulink block is generated from the Simulink block, denoted as “Filter” highlighted with blue colour.

During FIL co-simulation, Simulink simulates the design model and exports the input data to the FPGA platform via Xilinx ISE Design Suite interface. Then, the FPGA platform receives input data from the Simulink design model through Ethernet connection. After that, the Xilinx FPGA will execute and process the input data based on the algorithm of the “Filter” Simulink block. Next, the FPGA will send the data back to Simulink via Ethernet connection.

In summary, FIL co-simulation combines conventional simulation with Xilinx FPGA. It provides an alternative debugging environment so that it is possible to detect, isolate, identify and resolve bugs in the early stages.

At this point of the article, you should already understand the basic notion of FPGA-in-the-loop. To find out more on the functionalities, capabilities as well as the underlying attributes of FPGA-in-the-loop, you can visit the following site:

http://www.mathworks.com/products/eda-simulator/demos.html

Article by Dr. Chong Jin Hui, Senior Application Engineer

Matlab codes for active contour without edges (levelset based)

Somebody implemented the algorithm of active contour without edges (based Chan and Vese's paper) in Matlab athttp://www.postulate.org/segmentation.php. It runs well, but is slow.

Another Matlab implementation is by Dr. Chunming Li (who is a collaborator of Dr. Kao) and is available athttp://www.engr.uconn.edu/~cmli/code/. It is much faster and also has the implementation for multiple levelset functions.

MATLAB Codes for Image Processing

As I had promised, I am going to upload the files to various codes related to image processing in MATLAB. Starting from the simpler, I will move on to more complex codes. I have commented wherever the need be, in order to make the code understandable to a laymen. Suggestions are always welcome. I will keep on posting the links of file-hosting sites where I have uploaded my code. A single click will enable you to download the code. The codes have been written in MS Word. All you need to do is to copy-paste the code in the MATLAB editor, unless otherwise specified.

DOWNLOAD BELOW CODES

Bit-Plane Slicing Technique

Neighborhood of a pixel

Statistical order filtering

Convolution/correlation of two images

Edge-detection using HAAR filter

Color to gray conversion

Real-time face detection and tracking using OpenCV

Before some of you guys get paranoid after reading OpenCV and start googling for it, let me give a bird's eye view of what OpenCV actually is:

Developed by the researchers at Intel, OpenCV is an open source library of functions dedicated to image processing. OpenCV (Computer Vision) - as the name suggests, is primarily focused on image processing aspects. It has a very rich (and equally complex) library of functions - thanks to the fact that it is an open-source tool. Learning all of these functions is difficult, and I rather approached it in a different way - learn a function as and when I need them.

Okay, so I tried and developed some of the basic programs like displaying an image or a video feed in a window, real-time video feed from a webcam, accessing individual frames from a video and filtering them and so on. I did that to get acquainted with the tool. Let me tell you that those programs are not as tough as they sound - just a few lines of code and that would serve the purpose. Some of you might even think of it as waste of time, but trust me - the work will pay its dividends. Once I was comfortable with using the basic functionalities, I developed a slightly complicated program - 'Real time face detection and tracking'.

OpenCV can be used with Windows, Unix, MAC and can be augmented with a variety of compilers - VS C/C++, Eclipse and many more. I preferred to use it with Windows, VS 2008 and .NET framework. If you're familiar with OpenCV, you will know that you can even use a wrapper instead of the .NET framework, but since it was my first project, I rather decided to stay away from it. The general logical flow of the program follows. I'll try and upload the video of the same as soon as possible so that you can have an idea of what exactly does the stuff do. The code is available upon request (prefer to contact me on varunshah444[at]gmail[dot]com). I welcome queries/suggestions and related comments from everyone.

Logical flow:

1. Start the webcam, and gain access to the live feed from it

2. Access the individual frames (this is where your hardwork pays off!!)

3. Load a cascade classifier for front of the face, and do template matching

4. You will now have the location of the face(s) in your video

5. Draw a rectangle (or whatever god damn shape you prefer) around the detected object (face in our case)

For those who are familiar, I have used the classifier cascade method and not the 'training-images' one, because of few reasons:

1. The latter takes hell lot of time to generate the .xml file. Typically, 3-4 days of continuous processing

2. It's tad complex compared to the classifier cascade method

3. For a beginner, it's better to use the former method

The moment it compiled and started working, I was on Cloud9, pheww!!! It is a wonderful feeling when your hardwork ultimately pays off. As I always say - Work hard, party harder! Happy coding!!!

LET'S CODE MORE WITH TABLING THE OUTPUTS

Recall that from the first post, we have already:

Algorithm for any program should consists of three main sections - input, computation and output
Basic syntax for mathematical operation
Solving the assignment given

For this post, we will discuss on more coding.

P/S: Before I proceed, I would like to make some correction. From Figure 1.4, the semicolon (;) at the end of the last code line is preferably dropped to result in automation of output display when running the program.

Here is the new assignment given this week:

QUESTION:
Write a Matlab program, using a script M-file, that calculates the velocity and acceleration of an aircraft at time 0 to 120 seconds with increments of 10 seconds. Display the results in a table of time, velocity and acceleration.

The following are the equations to estimate the velocity and the acceleration of the aircraft:
velocity=0.00001*time.^3−0.00488*time.^2+0.75795*time+181.3566
acceleration=3−0.000062velocity.^2

NOTE: I will leave it to you to solve the algorithm and the flowchart before doing the Matlab code.

Here's how to do your simple Matlab code:

1. It is advised that you start your fresh code with the keyword clear as has been explained in the first post (Figure 2.1).

2. You are now required to define the input as t (time). #Suggested code can be obtained in the Figure 2.1. You can use t = input ('Insert range of time in s: '); as well although that would require you to key in

3. You are now required to compute the variable V (velocity) and A (acceleration) using the formula given in the question and with the variables t that you have defined as the input in step (2) (Figure 2.1). The code is as follows:

V = 0.00001*t.^3 - 0.00488*t.^2 + 0.75795*t + 181.3566;
A = 3 - 0.000062*V.^2;

Figure 2.1

TIPS: For computation of power, please make sure that you inserted .^ instead of ^ only. I am not sure what is the explanation but it seems that the latter won't work when running the program.

4. You need to define your output (or display or print). The question requires you to compute Velocity and Acceleration as the result, then display them in the table form (Figure 2.2). Therefore, the code is as follows:

table = [t' V' A'];

5. To display the output in the form of table with headings on top of it, use the following additional codes (Figure 2.2):

disp (' Time Velocity Acceleration ');

disp (table);

TIPS: The difference between step (4) and the additional step (5) is that step (4) results in tabulation of matrix that does not have the headings 'time', 'velocity' and 'acceleration' above the data when running the code.

Figure 2.2

6. Save your code and run it on the command window.

GOOD LUCK IN TRYING. Thank you for staying till the end of this article. Any improvements on the Matlab code can be submitted to the comment box below.

Article Source: bernard-greentea.blog

CODING A SIMPLE MATLAB CODE

Greetings and welcome to Bern’s section on the basic computation programming for engineers. In this first article that I have wrote for this special section on my blog, I would like to talk about constructing a simple computer language code using the Matlab for a common mathematical question. If you are my JKKP classmates, I am sure that you have the question for the assignment given by Dr Meor with you. If you are not, here is the question stipulated:

QUESTION:
The area of a triangle having side lengths a, b and c is:
Area = √(s(s-a)(s-b)(s-c)) - where; s = (a+b+c)/2

Write a computer code (Matlab) to prompt user for the three sides of a triangle and then compute and print the area using the relationship above. You are expected to submit the algorithm, flowchart and the computer (Matlab) code.

NOTE: I will leave it to you to solve the algorithm and the flowchart.

Here's how to do your simple Matlab code:

1. Open your Matlab software. Now, you are at the command window.

2. Type edit and enter. Now you have open the editor window.

Please note that the editor is the place you do the coding. The command window can be used to do so too, as well as served as a place for checking and experimenting. Analyze the question and do the proper algorithm before you start the coding. The algorithm should have the following:

Input - you are required to name the input A, B and C; as well as to define the S (I'm using capital letter here)
Computation - you are required to compute AREA
Output - you are required to determine the output, in this case is the AREA

3. First step; it is advised that you start your fresh code with the keyword clear (Figure 1.1).

TIPS: 'Clear' erases any existing variables and helps to reduce risk of errors that may arise.

4. Second step; you are now required to define the inputs. We have earlier, determined that we need to put three different inputs of a, b and c to initiate computation. Suggested codes are displayed in Figure 1.1 below:

Figure 1.1

The codes are divided into two distinguished commands here as in black and purple-colored text. The black-colored code defines the variables A, B and C or the side lengths of the triangle as the input. The purple-colored code, meanwhile is a description of the input variables that you can fill in when you run the code on the command window (we will get back to this later).

5. Third step; you will need to define and compute the variable S using the formula given in the question and with the variables A, B and C that you have defined as the input in step (4). The code is as follows:

S = (A+B+C)/2;

TIPS: Semi-colon (;) is inserted at the end of each code line (if necessary only) to stop the program from auto-computing that particular formula on that line. It may not be critical in the editor window but it will be in the command window.

6. Fourth step; you are now required to insert the computation code to compute area of the triangle based on the variables A, B, C and S. Use variable AREA to represent area. The code is as follows:

AREA = sqrt (S*(S-A)*(S-B)*(S-C));

TIPS: Figure 1.2 below shows the syntax for some basic mathematical operations:

Figure 1.2

7. The fifth step will be that you need to define your output (or display or print). The question requires you to compute AREA as the result. Therefore, the code is as follows:

Output = AREA;

8. There is no exact syntax code for stop here. Leaving it as it is should be subtle. Please note that adding stop or endat the end of the whole coding may causes error. End syntax should only used to close a loop or repetitive conditioning. After doing steps (1) to (7), your code should look something like the one displayed in Figure 1.3.

Figure 1.3

9. Save this file to your proper directory on the computer. For mine, I will save it as "AreaTriangle2" and will be saved to the Document directory. On the top of the editor window, Matlab will usually show the location of your saved file in within the directory of files (Figure 1.4).

Figure 1.4

10. Now, back to your command window. Type the name of the code file you have just saved. If you have type the name of the file correctly, you will get something as in Figure 1.5. If not, change the director or current folder.

Figure 1.5

11. Recall from step (4) about the purple-colored text. On the command window, you will know see the instruction "insert an integer for a". Type the value of side length a as the input for A then press enter. Do the same for B and C. For this example, I will insert A = 20, B = 10 and C = 15 (Figure 1.6).

Figure 1.6

12. If you have get your code correct, you should be able to get the AREA correctly. Type output and press enter. The output is the computed area of the triangle. You can always hit your calculator to check the answer (Figure 1.7). You can try with different values for A, B and C.

Figure 1.7

13. You have completed the assignment. Congratulation.

GOOD LUCK IN TRYING. Thank you for staying till the end of this article.

Article Source : bernard-greentea.blog