Sunday, December 29, 2013

Review of Linear Control Systems, In Brief.

Good day! 
Today, I'm going to rant 
a brief on a favourite 
(read: "favourite") 
subject of mine for this semester. 
ENT220/4 Linear Control Systems. 
I've posted on Instagram 
I've posted on Facebook 
about the syllabus
Now, allow me to elaborate about the subject 
a lil bit more. 
It's only suitable for people 
with mild engineering knowledge.

So before we go further 
This subject, simply put 
is all about 
lol, yeah. 
Exactly what the lecturer said 
at the first lecture 
as in 
"If you want to be queen/king of control, 
you must learn this subject" impression. 
Next, he came with this. 
"If you put your grandma into the input, 
you'll get your grandma from the output." 
That is, by having control of a particular system 
(or plant, as specified by throughout the course) 
You shall get the output 
exactly as it is desired 
(or in this case, as it is inserted at the input). 
It's clear anyway 
that the control we speak of here 
is the control in the context of engineering field. 

The first chapter's all about the basic terms
systems, sub-systems, plant, control, open & closed loop.  
and some revisions on Laplace Transforms (LTs)
so it's nothing much in particular. 
Boleh google sendiri kot istilah kat atas tu ea? Hihi
Afterwards, using the reaffirmed knowledge of LTs 
we learnt to deduce transfer functions 
from block diagrams 
and signal flow graphs 
also, by using the above 
we model a few systems 
deducing transfer functions outta them 
be it mechanical, electrial & biomedical 
Simple electrical system => RLC circuit 
Mechanical system consisting of
mass, spring, gears & damper
Biomedical system => ECG machine

Going forward 
we're being familiarized to analyze a system 
in time domain & frequency domain. 
A pinch of terms 101, 
system is something that produces output 
upon an input is fed into it 
while time domain & frequency domains 
are just like s-domain in LTs.  
might as well say it's similar to currencies used in banking 
so time & frequency domains be like American & Australian Dollar 
s-domain's like Britain Pound Sterling. Lol. 
In usual practices, it is just fine to do analysis 
in these two domains. 
Time domain analysis (TDA) 
is practical for most types of inputs 
(step, ramp, parabolic) 
while frequency domain analysis (FDA) 
is practical when the input is sinusoidal. 
We learnt a few more new terms & specifications 
unique to TDA & FDA respectively. 

For TDA 
we were taught to perform it in two situations:  
when the system is giving usual response (transient) 
and when it is stable (steady-state) 
also, new terms 
rise & settling time, time delay, maximum time, maximum overshoot 
and how damping factor affects a system response 
again, we compute the system response 
using LTs 
in cases of simple, multiple & complex poles 
(partial fraction thingy, if anyone recalls
also, we consider the steady-state error 
that difference between the output 
and reference input at steady-state 
considering the system isn't producing the exact result. 

As for FDA 
those new terms be like 
resonant peak & frequency, bandwidth & cut-off rate. 
Else, the focus is more on doing Bode plot & Nyquist plot 
Bode plot in MATLAB environment. 
An example of Nyquist plot
so as to estimate better the frequency response 
as well as determining system stability 
and converting it later for estimation in time response. 
Kalau dah datang US kenalah pakai US$ kan, 
takkan nak guna MYR pulak. Hew 

Last but not least 
what's the point of having the control 
if you're clueless about the system's stability? 
Realizing that (kononnya), 
we were exposed to a few techniques 
to examine the stability. 
namely Routh's Table 
and root locus 
one of those examples of root locus techniques
As a side note, 
Routh-Hurwitz's criterion 
is always the major consideration here. 
After knowing all these, 
we are acquired 
to design controllers 
be it PID or lead-lag. 
while PID or Proportional Integral Derivative type 
is a combination of PI & PD types, 
one features a good steady-state error & cut-off rate improvement  
while another features higher stability & bandwidth improvement 
thus PID is a compensation for both types 
as lead-lag 
is merely another name for PI-PD combo. 
In addition, Ziegler-Nichols First & Second Tuning Method 
are also applied 
in order to find parameters for said controller types 
Kp, Ti, Td 
assuming the plant's on transient response.

Well, that sums up the subject that consumes 
partly the past 14 weeks of four-hour lectures. 
Sorry for the extremely brief story, I guess. 
I'm in the attempt of 
lessening the gravity of the matter 
while keeping the interest intact in between 
nanti ada yang pening. Siapa tau 
Kepada sesiapa yang belajar benda ni untuk sem ni 
terutamanya geng satu kelas 
semoga berjaya! 
untuk subjek ni dan subjek-subjek yang sewaktu dengannya. 
Best wishes to everyone else whom taking finals too. 

P/S: Using sources from Wiki since I can't link sources from my varsity portal. 

Thursday, December 19, 2013

Pinky Promise With Myself, Made Public

Facebook posts
might disappear
or hard to relocate 
due to new posts 
and shares over time
so let's put it here 
a self-reminder for myself 
and an inspiration (hopefully) 
to people reading.

For I believe, the road of betterment isn't mine alone. 

Regarding my missions 
yes, they're still ongoing 
but let's just say 
I didn't prefer to post it here 
at the moment. 
Till then 
Selamat berjuang untuk kali yang ke-5 
buat rakan seperbarisan! ^_^

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