ao@milton.u.washington.edu (Allen Olson) (04/29/91)
I was wondering if there are any good articles comparing fuzzy control systems
to systems utilizing neural nets. I have read the following two articles, both
from last year's proceedings of the neural net conference:
"Comparison of Fuzzy and Neural Truck Backer-Upper Control Systems,"
Seong-Gon Kong and Bart Kosko, III, pp. 349-358.
"Fuzzy Control Using Neural Network Techniques," Toshiaki Iwata,
Kazuo Machida, and Yoshitsugu Toda, III, p. 365-370.
I would also like some feedback on the best places to use neural nets versus
using fuzzy systems. In particular, I would like some opinions to compare with
Kong and Kosko's opinions which I summarize loosely below:
Fuzzy systems use a small number of "linguistic" input-output samples while
neural nets use a large number of "numeric" input-output samples. The best
approach to take in a specific situation is dependent upon the type and
availability of the data. A fuzzy system should be used when structured
knowledge of the control process is available whereas neural nets should
be used when that structured knowledge is lacking. In general, therefore,
a control process that needs a neural net is likely to be rare since,
and I quote, "A neural network simply may not be the appropriate architecture
for many control problems. A more appropriate architecture may be a fuzzy
system of FAM-bank architecture, with embedded neural networks to adaptively
estimate individual FAM rules."
I tend to agree with Kong and Kosko's conclusions in general although I balk
at drawing the distinction between fuzzy and neural nets as "linguistic" vs.
"numeric." Though I know they are just trying to emphasize the rule-based
nature of fuzzy control, why not say just that and add that fuzzy controllers
are "intelligent" enough to interpolate between rules in a distinct numerical
fashion, whereas neural nets "create" their own rules to produce the desired
output from the given input?
What say you? I'd appreciate responses, either through email or the net.
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