RE: Question: Fast Div.-Algorithm for COG Defuzzification

Gunawan Setiabudi (guns@elang.stts.ac.id)
Tue, 11 Mar 1997 16:14:45 +0100


What about 68hc11?? Is this MCU can be a satisfying MCU to do the fuzzy
logic...?
On Tue, 11 Mar 1997, Constantin von Altrock wrote:

> Hi Wolfgang
>
> You posted the following question:
>
> > I'm interested in a (really) fast algorithm for the defuzzification
> > on a microcontroller system (8051). The problem is, that the general
> > division algorithm for the big division at the end of the COG-method
> > (16 Bit value divided by an 8 bit value) is quite time consuming and
> > all the implementations I know use a hardware based division.
> >
> > A speed up by the factor 5 to 10 would be enough (instead of 600
> > Microsec only 100 microsec or less ...)
>
> You are perfectly right. The final division consumes most of the
> computational effort on 8051-type MCUs. In a joint research project
> with the developers of the 8051 between the companies Intel and
> Inform, we have developed a code generator for fuzzy logic in the 8051
> that is capable of generating fuzzy logic systems that run in a
> millisecond (including fuzzification and rule inference) and consume
> only about 1/2 KB of ROM space. One key to this was the implementation
> of the COG defuzzification with a special division method.
>
> We are convinced that it is impossible to significantly improve the
> efficiency of the code our development environment for the 8051
> produces. If you are interested in benchmarks and details, refer to
> the fuzzyTECH Home Page at http://www.fuzzytech.com.
>
> By the way, in a straightforward implementation of the
> defuzzification in 8 bit computational resolution the 16/8 division
> does not suffice as the computation of the COG requires to sum a
> number of 8x8bit multiplication results (which may be more than
> 16bit), and divide it by the sum of a number of 8 bit variables (which
> may be more than 8 bit). Thus the 16/8 bit division will not suffice
> for a straightforward implementation.
>
> Constantin
>
> Constantin von Altrock
> e-mail: cva@inform-ac.com
>
> INFORM GmbH
> Pascalstrasse 23
> D-52076 Aachen, GERMANY
> WWW: www.fuzzytech.com
>
> Phone: +49-2408-945680
> Fax: +49-2408-945685
>
> Constantin von Altrock
> e-mail: cva@inform-ac.com
>
> INFORM GmbH
> Pascalstrasse 23
> D-52076 Aachen, GERMANY
> WWW: www.fuzzytech.com
>
> Phone: +49-2408-945680
> Fax: +49-2408-945685
>

Gunawan Setiabudi
<guns@techie.com>