HCS12 datasheet(339/452 Pages) FREESCALE

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S12CPUV2 Reference Manual, Rev. 4.0

Freescale Semiconductor

339

solve certain types of complex problems that have eluded traditional control

methods.

Fuzzy sets provide a means of using linguistic expressions like

“temperature is warm” in rules which can then be evaluated with a high

degree of numerical precision and repeatability. This directly contradicts the

common misperception that fuzzy logic produces approximate results — a

specific set of input conditions always produces the same result, just as a

conventional control system does.

A microcontroller-based fuzzy logic control system has two parts:

• A fuzzy inference kernel which is executed periodically to determine

system outputs based on current system inputs

• A knowledge base which contains membership functions and rules

Figure 9-1 is a block diagram of this kind of fuzzy logic system.

Figure 9-1. Block Diagram of a Fuzzy Logic System

INPUT

MEMBERSHIP

FUNCTIONS

RULE LIST

OUTPUT

MEMBERSHIP

FUNCTIONS

FUZZIFICATION

RULE EVALUATION

DEFUZZIFICATION

FUZZY

INFERENCE

KERNEL

KNOWLEDGE

BASE

SYSTEM

INPUTS

SYSTEM

OUTPUTS

FUZZY INPUTS

(IN RAM)

FUZZY OUTPUTS

(IN RAM)

…

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