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                            Fuzzy Logic Applications
                                Fuzzy Classifier
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A fuzzy based signal analyzer and classifier has been developed using TIL's
FC110 Digital Fuzzy Processor.  In the demonstration that was constructed,
different makes of tennis balls were classified using digital signal processing
(DSP) and fuzzy logic combined.   Classification in this example was a
difficult problem because there were no given criteria in the time domain or
the frequency domain.  Fuzzy logic was a simple and quick method for
establishing these criteria.

With the demonstration system, tennis balls are dropped and the acoustical
signals created by the balls bouncing off a metal plate are measured.  The
system (see Figure 2 [not present in this text-only version]) is made up of
three components: the analog input module, the DSP module and a Fuzzy Lab (the
FC110 based board developed by GTS, TIL's distributor in Germany.)  This unit
is connected to an IBM PC compatible running the TILShell and the FC110
Development System.

Signal inputs come in via a microphone.  After low pass fourth order filtering
and A to D conversion, a built-in transputer does the fast fourier transform. A
typical FFT spectrum is shown at the top of Figure 3 [not present in this text-
only version].  Interesting signal frequencies in the range of 1000 to 2500 Hz
are subdivided by intensity pattern into the 10 categories (see bottom of
Figure 3) which are inputs to the fuzzy processor.

It was found that fifty was a sufficient number of trials for determining a
good Gaussian form for the membership functions (mbf) and to establish an
accurate classification system.  The  variation and average of each mbf is a
function of the learning process involved with multiple trials of ball
dropping.  Almost 100% accuracy in classifying the brand of ball was achieved.

This type of classification system has a a wide variety of applications
including vibration analysis, manufacturing,  quality assurance and error
detection.  For more information contact GTS at:

GTS Trautzl GmbH
Gottlieb-Daimler-Strae 9
D-2358 Kaltenkirchen
Germany
Tel.: 0 41 91 / 87 11
Fax: 0 41 91 / 8 86 65 
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Copyright (c) Togai InfraLogic, 1992.  All rights reserved.
Permission to freely distribute this document, provided that it remains
complete and intact, is hereby granted.
