science

Fuzzy Control Language

Fuzzy Control Language is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Fuzzy Control Language rather than just read about it. In short: Fuzzy Control Language, or FCL, is a language for implementing fuzzy logic, especially fuzzy control. It was standardized by IEC 61131-7.

Key takeaways

Fuzzy Control Language belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Fuzzy Control Language to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Fuzzy Control Language from memory before moving on to harder problems.

Reference excerpt

Fuzzy Control Language, or FCL, is a language for implementing fuzzy logic, especially fuzzy control. It was standardized by IEC 61131-7. It is a domain-specific programming language: it has no features unrelated to fuzzy logic, so it is impossible to even print "Hello, world!". Therefore, one does not write a program in FCL, but one may write part of it in FCL.

Example RULE 0: IF (temperature IS cold) THEN (output IS low) RULE 1: IF (temperature IS very cold) THEN (output IS high)

Limitations FCL is not an entirely complete fuzzy language, for instance, it does not support "hedges", which are adverbs that modify the set. For instance, the programmer cannot write: RULE 0: If (Temperature is VERY COLD) then (Output is VERY HIGH) However, the programmer can simply define new sets for "very cold" and "very high". FCL also lacks support for higher-order fuzzy sets, subsets, and so on. None of these features are essential to fuzzy control, although they may be nice to have.

References

External links fuzzyTECH, Archived 2008-07-17 at the Wayback Machine a commercial fuzzy logic development system containing the specification document for IEC1131-7 (select Fuzzy Application Library) IEC 1131-7 CD1 Archived 2021-03-04 at the Wayback Machine IEC 1131-7 CD1 PDF fuzzylite, A fuzzy logic controller library written in C++. Free Fuzzy Logic Library (FFLL), an implementation library written in C++. JFuzzyLogic, open source FCL + Fuzzy Logic Package (sourceforge, java) AwiFuzz, open source implementation written in C++ covering all three levels of IEC 61131-7 Fuzzy Controller Language pyfuzzy, open source implementation written in python.

Worked examples

Example 1 — a first encounter with Fuzzy Control Language

Start with the simplest possible case. Write down what Fuzzy Control Language claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Fuzzy Control Language before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Fuzzy Control Language ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Fuzzy Control Language

In research: Fuzzy Control Language appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Fuzzy Control Language in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Fuzzy Control Language is common in secondary-school and first-year university syllabi. It links to neighbouring topics Domain-specific programming languages, Fuzzy logic, Programming language topic stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Fuzzy Control Language outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Fuzzy Control Language in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Fuzzy Control Language means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Fuzzy Control Language out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Fuzzy Control Language in simple terms?

Fuzzy Control Language, or FCL, is a language for implementing fuzzy logic, especially fuzzy control. It was standardized by IEC 61131-7.

Why does Fuzzy Control Language matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Fuzzy Control Language?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Fuzzy Control Language.