>The fact that the
>PID algorithm can be proven to be mathematically correct only means that
>the math works. As far as I know the PID model has never been shown to
>be an exact analog of any real physical process.

It seems very real to me, rates of change and averages over time I can
understand.

> since it works so well for these
>situations, it gets used.

Maybe its employed so well because its principals (calculus) is generaly
taught and well understood. Impulse response and damping in the time domain,
or frequency responce, pass/stopbands in the frequency domain, and pole zero
diagrams model many physical systems very well. Where are the fuzzy logic
analysis tools?

>Fuzzy logic is just that: a new technique, a new algorithm.
...
>Paradigms are metamodels,
...
>It's easy to see that you can chase your
>metamodels to a point where you are trying to define the fundamentals of
>existence.

I think, therefore, I am confused :(

...
>Did you get that?

No.

>So what I propose is this: we should try to think of fuzzy logic as a
>different way of approaching the development of problem solving
>strategies. In this light, there is no comparison with PID algorithms or
>any other general solution or model.

You mean I can't build a temperature or motor speed controller, and compare
the resources (MIPS, RAM space, ROM space, et) required, the length of
learning curve, the time to code, and the performance of a PID vs. FUZZY
implementation? Bob Pease' somewhat critical artical in EDN commented on
some of these points.

>P.S. Just in case you wondered, I don't believe that there is going to
>be a giant penetration of fuzzy logic solutions into our little world
>anytime soon. --TR
>

I think your right.

I have probably spent four or five hours reading about fuzzy logic over the
last few years. All the rule-writing makes me think the compiler is
generating some kind of look-up table. The esoteric buzzwords fuzzify
understanding. I suspect it's a marketing ploy. Engineers will pay for the
latest fashion trend in software, to hide their embarrasement over their
confusion.

Until I understand how the fuzzy compiler turns rules into code, and I see
clear performance advantages, I won't invest time and money to climb what
looks like a steep and unrewarding learning curve. Without some type of
numeric analysis method to create a transfer function, fuzzy logic is scary.
Memories of hours spent tuning four-pole filters come to mind. Microchip's
ball-balancer AN600 hasn't changed my mind. I have no idea what the nature
of the generated code is, or how to quantify it or the system its controlling.

I guess its good, if you don't care how and why it does the job, and like
twiddling dials.

Just my narrow-minded, ignorant, conservative, traditionaly-educated 2 cents.