Re: Fuzzy vs Neural


Subject: Re: Fuzzy vs Neural
From: Bruce Postlethwaite (b.postlethwaite@strath.ac.uk)
Date: Tue Jan 11 2000 - 12:13:26 MET


I think stability proofs are a bit of a fantasy in real applications (as
opposed to simulations) since they depend on you knowing exactly what the
process is (otherwise you can't prove anything). The conventional approach
to this is to prove stability over a range of possible expected model
conditions - this is no different in quality to testing a fuzzy system over
a range of conditions.

The big advantage of the fuzzy approach is in non-linear control. It
provides a compact, easily manipulable, model which can be used in
model-based controller formulations. My company, Process Cybernetics
http://www.procyb.com/, is involved in this area, and we've found the fuzzy
approach very useful in things like dryer and fermenter control.

Bruce Postlethwaite
Process Cybernetics Ltd

pandeyashish@my-deja.com wrote in message <854u2k$otd$1@nnrp1.deja.com>...
>There exists no proof of stability. It means that you have no proof
>what so ever that the fuzzy logic controller in closed loop is going to
>remain stable or not.
>
>Since model based controls for a process like the one you described are
>well established I see no reason that you would like to venture into a
>grey area.
>
>
>I think you must have a good reason for using a FLC( this also remains
>a grey area) Dont implement FLC just cause they sound cute as there is
>no justification for their use in processes where mathematical models
>exists.

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