# I can't seem to find any detailed example of fuzzy control on the net

From: Ephestione (ephestione.donotbotherme@yahoo.com)
Date: Mon May 28 2001 - 07:13:54 MET DST

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I study Dentistry, and, even if it could seem absurd, I need to catch
the FL control meaning to develop -even if only theorically- an expert
system to study the cefalometric measurements of a population, so to
see who are the ones in the "normal" range and the ones who aren't..
based on a series of rules about bone angles and lenght and so on --
this is all for my graduation work.

Well for now I am looking for an example of applicated fuzzy control..
about everything, but just a simple example to make FL clear. I tried
myself to develop a fuzzy control algorithm, to make a washing machine
open or not the box of the soap, depending on the water tank (say 20
liters) being more or less full, and anyway open it unconditionally
after 4 minutes. This obviously just to see if I was able to start
from scratch.. well I got stuck after the composition (I followed the
official FL FAQs).

These were the rules I made:

- IF the watertank is full THEN the soapbox is open

- IF the watertank is empty THEN the soapbox is closed

- IF the timer is ringing THEN the soapbox is open

being these the functions I made:

- full(x) = x/20 ;water tank is 20 liters

- empty(x) = 1 - x/20

- ringing(x) = {0, if 0=< x <= 220secs ;4 mins = 240 secs
x/20 - 11, if 220< x <= 240 secs }

I think I can only use the MAX-MIN method here to make the 4mins timer
rule to work.

So... after I inferenced, and composed, I get a fuzzy(::unknown
variable::) function (for each value of watertank level and timer
seconds) which, since I only need to know wheter the soapbox has to be
open (1) or closed (0), I have to defuzzify...

I get lost here!

I mean.. the FAQs give me no info when I have to use Average of maxima
(is it only used in combination with MAX-MIN method?) or Centroid (is
it only used in combination witrh PRODUCT-SUM method?) on a function
which values should only vary in {0,1}...

Am I wrong?
I feel just lost.

BTW I just started from scratch 2 weeks ago, not even knowing what FL
was... and I need something to tell the orthodontics professor for
thursday ;-)
I mean, my work will be totally theorical, but this technical detail
is necessary at the beginning to introduce me to the subject.
So... just a "debug" of the "thing" I made, or an URL to everythig
explaining in detail the development of a very very simple fuzzy
controller would make the deal :-}

Thank you even only for reading till here

Regards

----------
Ephestione

"Mommy the garbage man is here!" "Tell him we don't want any"
- Groucho Marx

ephestione at yahoo dot com

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