IEC 61131-7:2000 pdf download
IEC 61131-7:2000 pdf download.Programmable controllers -Part 7: Fuzzy control programming.
3.15
linguistic rule
IF-THEN rule with condition and conclusion, one or both linguistic
3.16
linguistic term
in the context of fuzzy control, linguistic terms are defined by fuzzy sets
3.17
linguistic variable
variable that takes values in the range of linguistic terms
3.18
membership function
function which defines the degree of membership over the universe of discourse for a given fuzzy set
11EV 351-17-52, modifiedl
3.19
singleton
fuzzy set whose membership function is equal to one at one point and equal to zero at all other points
3.20
subcondition
elementary expression in the form of a variable or as term “linguistic variable iS linguistic term”
3.21
rule base
collection of linguistic rules to attain certain objectives
3.22
weighting factor
value between O..1, that states the degree of importance, credibility, confidence of a linguistic rule
4 Integration into the programmable controller
The fuzzy control applications programmed in Fuzzy Control Language FCL according to clause 5 shall be encapsulated in Function Blocks (or Programs) as defined in lEG 61131-3. The concept of Function Block Types and Function Block Instances given in IEC 61131-3 applies to this standard.
The Function Block Types defined in Fuzzy Control Language FCL shall specify the input and output parameters and the fuzzy control specific rules and declarations.
The corresponding Function Block Instances shall contain the specific data of the fuzzy control applications.
In this example, Valve_Control_i is a user defined Function Block Instance of the Function
Block Type Fuzzy_FB. The Function Block Type Fuzzy_FB may be programmed in Fuzzy
Control Language FCL according to clause 5. The Function Block Fuzzy_FB is used here in a
program or a Function Block which is represented in the graphical language FBD (Function
Block Diagram) of IEC 61131-3.
5 Fuzzy Control Language FCL
5.1 Exchange of fuzzy control programs
The definition of the Fuzzy Control Language FCL is based on the definitions of the programming languages in IEC 61131.3. The interaction of the fuzzy control algorithm with Its program environment causes it to be Thidden from the program. The fuzzy control algorithm is therefore externally represented as a Function Block according to lEG 61131-3. The necessary elements for describing the internal linguistic parts of the fuzzy control Function Block like membership functions, rules, operators and methods have to be defined according to this clause.
The language elements of FCL standardize a common representation for data exchange among fuzzy control configuration tools of different manufacturers shown in figure 2. Using this common representation, every manufacturer of programmable controllers may keep his hardware, software editors and compilers. The manufacturer has only to implement the data interface into his specific editor. The customer would be able to exchange fuzzy control projects between different manufacturers.
With this definition，all simple elements， for example ramp and triangle，may be defined.Thepoints shall be given in ascending order of variable value.The membership function is linearbetween successive points.The degree of membership for each term is therefore calculatedfrom the crisp input value by the linear interpolation between the two relevant adjacentmembership function points.
The minimum number of points is two. The maximum number is restricted according toclause 6 conformance classes.
The rule itself shall begin with the keyword lF followed by the condition. After the condition, theconclusion follows,beginning with the keyword THEN.
lt is allowed to combine several subconditions and input variables in one rule.The purpose ofvariables is to permit fuzzy degrees of membership to be imported into the fuzzy FunctionBlock.All of them shall be defined between the keywords lF and THEN, and combined by theoperators with the keywords AND,OR or NOT.
The priority of the operator (see table 6) is handled according to Boolean algebra given in table 3.
ln the Basic Level of conformance,the OR operation may be implemented by defining two rules.
