Please, correct me if I'm wrong (OK, so you would have anyway), but I keep
seeing references to FL 'learning' better responses to input.  I thought FL
was just a way to deal with ambiguous (not yes or no) inputs, and that
learning was the domain of neural software.  I can see how the neural
weighting is a form of FL, but not the other way around.  Am I completely
out in left field?


Martin R. Green
elimar@bigfoot.com

----------
From:   David Thornton[SMTP:david-t@SA.SCITEC.COM.AU]
Sent:   Wednesday, September 03, 1997 7:39 PM
To:     PICLIST@mitvma.mit.edu
Subject:        Re: Fuzzy Control Tool (was Re: PID Temperature Controller

> > > Pease Porridge of
> > > Electronic Design ran a contest for a Fuzzy Control system that he
> could not
> > > duplicate or exceed the performance of.  He won every challenge using
> op-amps
> > > and classic control theory. Fuzzy Control and Fuzzy Logic has had
lots
> of
> > > boasting and very little real substance.

> When ... developing Fuzz-C we looked hard for applications
> where fuzzy worked as well or better than conventional PID. When we did
> we found that PID was highly optimized for a narrow range of
> applications and fuzzy was a more general case.
>
> For example look at the momentum difference in an aircraft control system
> after the fuel stored in the wings has been burned in flight. A PID
control
> loop in such a system is very hard to tune.


It may not be fair to compare PID vs. fuzzy. The biggest strength or
advantage you will obtain with a fuzzy logic is the range of
applications, the ability not only to have a competitive performance
where PID work well but also acceptable results in some applications
PID, or any other conventional control methodology, poorly works or
does not work at all.

But it may not be the most precise controller you can come up with
when you have other alternatives. Nevertheles, it is very robust and
simpler to implement.

__Aydin
I suggest you examine Mitsubishi's newest automatic gearboxes, these
use fuzzy logic, they are not perfect but are a huge improvement over
previous electronic & hydraulic systems found on other cars that I
have driven. Apparently early versions of software could learn bad
habits!!
David.