ADVANCED WORKSHOP IN MATLAB

MATLAB FOR ALL ENGINEERS

ADVANCED WORKSHOPDecember-13th-2016

MECHANICAL ENGINEERING DEPARTMENT

Dr. SAEED J. ALMALOWI

COLLEGE OF ENGINEERING

What can you gain from the WORKSHOP ?

Know basics of MATLAB/GUI/Simulink?

know how to solve simple problems?

Know what MATLAB/GUI/Simulink is?

Know how to get started with MATLAB/GUI/Simulink?

Be able to explore MATLAB/GUI & Simulink on your own !

INTRODUCTION TO MATLAB/GUI&SIMULINK

3

Built in functions

Getting Started

Vectors and Matrices

1. INTRODUCTION

2. GRAPHICAL USER INTERFACE

Examples

Introduction to MATLAB

GUI

M–files : script, Plots, Animation, and Functions 3. SIMULINK

Modeling Examples Simulink

CONTENTS

Plots: 1D plot “ plot(t,x)”, 2D plot, “contourf(Z)’’ ,Surf plot , and 3D plot.

Animation: gif (animated plots) or avi (Video).

Functions:

The functions AVI ang GIF are interchangeable. They both turn all image files from a

given folder into a movie file.

function y = average(x)

if ~isvector(x) error('Input must be a vector')

end y = sum(x)/length(x);

end

PLOTS, ANIMATION, & FUNCTIONS

clear all

clc

x=0:0.01:1;

y1=-x.^3+x.^2+1;

y2=1./x.^2+10*x+5;

y3=x.^4+exp(-x)+2;

subplot(3,1,1)

plot(x,y1)

xlabel('x');ylabel('y1')

grid on

plot(x,y1)

subplot(3,1,2)

plot(x,y2)

xlabel('x');ylabel('y2')

grid on

subplot(3,1,3)

plot(x,y3)

xlabel('x');ylabel('y3')

grid on

SUBPLOTS

𝑦1 = −𝑥3 + 𝑥2 + 1

𝑦2 =1

𝑥2+ 10𝑥 + 5

𝑦3 = 𝑥4 + exp(−𝑥) + 2

frame = getframe(1);

im = frame2im(frame);

[imind,cm] = rgb2ind(im,256);

if k == 1;

imwrite(imind,cm,filename,'gif',

'Loopcount',inf);

else

imwrite(imind,cm,filename,'gif','WriteMode'

,'append');

end

filename = 'upwind.gif'; Open file and name it!!!

Creating A frame

Upwind Method (Scheme)

GIF ANIMATED PLOTS

% Clear workspace

clear

clc

clf

% Define variables

N=100; % number of nodes

L=1; % The length of the domain

dx=L/(N);

x=0:dx:L;

ti=0; % Initial time

tf=0.8; % Final time

v=0.5; % Velcoity

dt=dx/v;

% Set Initial condition

uo=exp(-200*(x-0.25).^2);

u=uo;

unp1=uo;

% Loop through the time

nsteps=tf/dt;

t=ti;

filename = 'upwind.gif';

for k=1:nsteps

% BCs

u(1)=u(1);

u(N)=u(N);

% Exact Solution

% Calculate the FOU scheme

for i=2:N-1

unp1(i)=u(i)-v*dt/dx*(u(i)-u(i-1));

end

ua=exp(-200*(x-0.25-v*t).^2);

% Update u and t

t=t+dt;

u=unp1;

% Plot solution

plot(x,u,'bo-',x,ua,'r--')

xlabel('x')

ylabel('u')

shg

axis([ 0 L -0.5 1.5]);

grid on

pause (dt)

title(['Velcoity u (Time in [sec] is

' num2str(t) ')']);

drawnow

frame = getframe(1);

im = frame2im(frame);

[imind,cm] = rgb2ind(im,256);

if k == 1;

imwrite(imind,cm,filename,'gif',

'Loopcount',inf);

else

imwrite(imind,cm,filename,'gif','WriteM

ode','append');

end

end

To get GUI, write guide in command window as:

𝑑𝑥2

𝑑𝑡2+ 3η

𝑑𝑥

𝑑𝑡+ 4𝑥 = 1

textbox1

function textbox1_Callback(hObject, eventdata,

handles)

% hObject handle to textbox1 (see GCBO)

% eventdata reserved - to be defined in a

future version of MATLAB

% handles structure with handles and user

data (see GUIDATA)

% Hints: get(hObject,'String') returns contents

of textbox1 as text

% str2double(get(hObject,'String'))

returns contents of textbox1 as a double

str=get(hObject,'String');

set(handles.slider1,'value',str2num(str));

𝑑𝑥2

𝑑𝑡2+ 3η

𝑑𝑥

𝑑𝑡+ 4𝑥 = 1

function slider1_Callback(hObject, eventdata,

handles)

% hObject handle to slider1 (see GCBO)

% eventdata reserved - to be defined in a future

version of MATLAB

% handles structure with handles and user data

(see GUIDATA)

% Hints: get(hObject,'Value') returns position of

slider

% get(hObject,'Min') and

get(hObject,'Max') to determine range of slider

val=get(hObject,'Value');

set(handles.textbox1,'String',num2str(val));

slider1

𝑑𝑥2

𝑑𝑡2+ 3η

𝑑𝑥

𝑑𝑡+ 4𝑥 = 1

function runsimulation_Callback(hObject, eventdata, handles)

% hObject handle to runsimulation (see GCBO)

% eventdata reserved - to be defined in a future version of

MATLAB

% handles structure with handles and user data (see

GUIDATA)

eta=get(handles.slider1,'value');

G=tf(1,[1,3*eta,4])

time=linspace(0,20,200);

[x]=step(G,time);

axes(handles.axes1);

plot(time,x)

hold on

grid on

xlabel('Time')

ylabel('x')

cla(handles.axes1)

𝑑𝑥2

𝑑𝑡2+ 3η

𝑑𝑥

𝑑𝑡+ 4𝑥 = 1

Note: η changes from 0.01 till 2.

The above differential equation

can be solved analytically.

GUI can be added to APPS: press

on Apps icon, then package Apps

.Upload your code from “add main

file". Then write app information

and then press on package.

13

Model – simplified representation of a system – e.g. using mathematical

equation.

We simulate a model to study the behavior of a system – need to

verify that our model is correct – expect results

Knowing how to use Simulink or MATLAB does not mean that you know how to model a

system.

SIMULINK: WHY DO WE NEED IT?!!

Start Simulink by typing simulink at Matlab prompt

Simulink library and untitled windows appear

It is here where we

construct our model.It is where we

obtain the blocks to

construct our model

SIMULINK: LIBRARY

Creating a New Model

Press on New, then Model.

Save as your model.

Go to Simulink library browse

to add an element.

SIMULINK: ELECTRICAL APPLICATIONS

SCOPE/ RESULTS

ma = F t − kx − bv

Second Order Dynamic System

MECHANICAL APPLICATIONS

SIMULINK: ELECTRICAL APPLICATIONS

Simple Circuit- Krishof's Voltage and Current Law.

Problem: We need to simulate the resonant circuit and display the current waveform as we

change the frequency dynamically.

i 10 100 uF

0.01

H

Varies

from 0 to

2000 rad/s

Observe the current. What do we expect ?

The amplitude of the current waveform will become maximum at resonant frequency, i.e. at

= 1000 rad/s

+

v(t) = 5 sin t

–

SIMULINK: ELECTRICAL APPLICATIONS

idtC

1

dt

diLiRv

Writing KVL around the loop,

LC

i

dt

id

L

R

dt

di

dt

dv

L

12

2

Differentiate wrt time and re-arrange:

Taking Laplace transform:

LC

IIssI

L

R

L

sV 2

LC

1s

L

RsI

L

sV 2

SIMULINK: ELECTRICAL APPLICATIONS

Thus the current can be obtained from the voltage:

LCs

L

Rs

LsVI

1

)/1(

2

LC

1s

L

Rs

)L/1(s

2 V I

SIMULINK: ELECTRICAL APPLICATIONS

Constructing the model using Simulink:

1

s+1

Transfer Fcn

simout

To WorkspaceSine Wave

‘Drag and drop’ block from the Simulink library window to the untitled window

100s

s +1000s+1e62

Transfer Fcn

v

To Workspace1

i

To WorkspaceSine Wave

THINK !!!

START CREATING

YOUR SIMULINK

SIMULINK: ELECTRICAL APPLICATIONS

talent@taibahu.edu.sa

Contact us

@talent_taibah

QUESTIONS??????