Fuzzy Control Language
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.
 | This article relies largely or entirely on a single source. (March 2026) |
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.[1]
Example
[edit]RULE 0: IF (temperature IS cold) THEN (output IS low) RULE 1: IF (temperature IS very cold) THEN (output IS high)
Limitations
[edit]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
[edit]- ^ International Electrotechnical Commission (2003). Programmable controllers – Part 7: Fuzzy control programming (standard). International Electrotechnical Commission. ISBN 2831853842. IEC 61131-7:2003.
External links
[edit]- 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.
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