steven Olson <PICLIST@MITVMA.MIT.EDU> wrote:

> >What's the FuzzyTECH MP explorer board from Microchip about?  What
> >does fuzzy logic in a processor do exactly?
>
> The FuzzyTech MP from Microchip allows you to explore using fuzzy
> logic in a PIC controller. I believe it also has a software demo
> program. I do not own one yet. Soon I will :>

    FuzzyTech is a Windows-based fuzzy-logic development tool
    written by a German company called Inform.  The
    Microchip-specific version (FuzzyTech-MP) includes a HARDWARE
    demo, in the form of a 16C71-based thermostat control.

> Fuzzy logic is a super-set of binary logic. It more closely
> approximates human intellegence than binary logic ever could. Binary
> logic has two values: TRUE or FALSE. Fuzzy logic has many values in
> between true and false.

    I hear this a lot... As far as I'm concerned, it's a load of
    crap.

    Binary logic has only two values, right?  So how is it possible
    that a digital watch can show any number of values between
    midnight and noon?  How does the PIC's built-in A/D converter
    measure and represent voltage levels between 0V and 5V?  How can
    a fuzzy-logic-based control program be written for a
    microcontroller whose basic architecture predates the invention
    of fuzzy-logic by a decade or more?

    Hmm?

> One example of a fuzzy logic application that I like is in an
> automatic transmission.
>
> I used to have a volkswagon dasher that I would drive between
> Petaluma and Santa Rosa CA. One of the hills that I had to climb on
> the freeway would just about drive you crazy. The transmission would
> shift between 2nd and 3rd and back to third about every 10 seconds.
>
> Cars that use fuzzy logic in the transmission would realize after a
> few shifts back and forth that the car cannot sustain speed in the
> higher gear and wait until a higher RPM was reached before
> attempting to shift to third.

    ... And this is impossible to do with a more-traditional
    electronic transmission controller?  Please.

> I am only learning about fuzzy logic now, I am sure others have
> better explanations.

    Please don't take this message personally, Steve... I just think
    that fuzzy-logic has little application in control applications.
    If you're building a pendulum-balancer, thermostat, or even an
    automotive transmission or anti-lock brake system, you can do
    the job just as well (or, depending upon how you define the
    word, "better") using traditional methods.

    Fuzzy-logic has one advantage in control systems:  It's a quick
    and easy way to build software that ALMOST works.  However, this
    is outweighed in most cases by the time required to tweak the
    parameters of your fuzzy model until the software works
    acceptably; most fuzzy-logic "development" is performed by
    trial-and-error guesswork.

    On top of this, it's nearly impossible to prove that your final
    design is optimal.  It's even hard to guarantee (for complex
    fuzzy control systems, anyway) that the software won't exhibit
    wildly pathological behavior at certain points... Not a good
    thing fore control systems that are used in critical safety
    applications.

    Lotfi Zadeh, the inventor of fuzzy logic, has repeatedly stated
    that there are certain control problems which simply cannot be
    solved using techniques other than fuzzy-logic.  I think he's
    wrong.

    Bart Kosko, a professor at USC and the author of a couple of pop
    fuzzy-logic books, says that because fuzzy-logic can be used to
    emulate ANY control algorithm -- it's a superset of all the other
    programming paradigms -- it's obviously superior.  I think
    he's wrong, too... Assembly language is a "superset" of all other
    programming languages, but I wouldn't exactly call it "superior"
    for all applications.

    If fuzzy logic is good for ANYTHING other than rapid modeling,
    it's NON-control problems.  At the last fuzzy-logic conference I
    attended (a couple of years ago), someone stood up in the big
    question-and-answer session and told the panel,

        "I don't CARE about fuzzy logic in control applications...
        I'm perfectly happy with PID and other algorithms which can
        be mathematically proven to be correct, are well-understood,
        and don't require me to dick with my model for weeks on end.
        What I want to see is a fuzzy-logic model of something
        REALLY fuzzy... Like NAFTA [for those of you outside the
        U.S. who may not know, NAFTA, the North American Free Trade
        Agreement, was a controversial piece of national legislation
        that removed all trade barriers between the US and
        Canada/Mexico].

        "Why doesn't someone build a fuzy-logic model of the economy
        (which is so little-understood that there ARE no satisfying
        mathematical models), plug in the NAFTA variables, and tell
        us whether this will be good or bad for the country?"

    THIS guy, I think, was on the right track.

    If you're interested in doing control apps using fuzzy-logic,
    the FuzzyTech-MP product is one of the best.  I beta-tested a
    couple of versions of it, and Inform has done a really superior
    job of making the software powerful and easy to use.  If you're
    interested in fuzzy-logic on a grander scale, check out
    ByteCraft's "Fuzz-C" preprocessor... It's one of the standards
    of the industry.

-Andy

P.S.  Sorry for the length of this message... It's just that I HATE
      hearing that fuzzy-logic closely mimics the operation of the
      human brain.  It's just not true... At best, the process of
      DEVELOPING fuzzy-logic applications is easier for non-engineers
      than traditional methods, because IT mimics the way that they
      express and solve real-life problems.

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499