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Fuzzy logic, which started with ...

Posted Sep 11 2008 3:38pm

Fuzzy logic, which started with a 1965 paper by Lotfi Zadeh, a professor of computer science, is an advanced form of engineering; self-experimentation is a kind of primitive science. They seem to be at opposite ends of a continuum. As science advances — as knowledge becomes wider and more accurate — it becomes more and more useful, gradually becoming engineering. Fuzzy logic is an especially useful form of engineering.

A few years ago I attended a talk by Zadeh in the Berkeley Physics Department colloquium series. He showed a little movie of a platform moving back and forth to balance three linked poles. It was staggering that this was possible. It is a classic problem in control theory. Here is an example with two linked poles:

Fuzzy logic has proved especially useful in building control systems. An early example was furnace control; one of the first real-life examples was a Japanese subway system. Many consumer electronic products, especially those from Japan, use fuzzy logic. One of my Omron blood pressure meters uses fuzzy logic, says the box. (Omron now uses the term IntelliSense instead.)

When an engineer builds a control system, he doesn’t start from scratch, choosing from among all possibilities. Rather, he tries to embody in a computer program what a person would do. The program embodies a series of rules. Fuzzy logic provided a new and better language for describing those rules. It “bring[s] the reasoning used by computers closer to that used by people,” Zadeh has said. People use “vague” rules: If you are near a corner, slow down. Now it was easy to add such rules to control systems.

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