Lecture 12

Introduction to Neural Networksand Fuzzy Logic

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Dr.-Ing. Erwin SitompulPresident University

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2 0 1 3

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Solution: Homework 8Fuzzy ControlFuzzy Logic

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FC with 5 Rules

Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

Rule 1: IF level is okay, THEN valve is no change.Rule 2: IF level is low, THEN valve is open fast.Rule 3: IF level is high, THEN valve is close fast.Rule 4: IF level is okay AND rate is negative,

THEN valve is open slow.Rule 5: IF level is okay AND rate is positive,

THEN valve is close slow.

Rule 1: IF error is zero, THEN valve is no change.Rule 2: IF error is positive,THEN valve is open fast.Rule 3: IF error is negative,THEN valve is close fast.Rule 4: IF error is zero AND error rate is positive,

THEN valve is open slow.Rule 5: IF error is zero AND error rate is negative,

THEN valve is close slow.

error = reference – levelrate of error = – rate of level

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

Valve control signal [%/s]

no

chan

ge

ope

n fa

st

clos

e fa

st

–30 –20 –10 0 10 20 30

1 o

pen

slow

clos

e slow

Rate of level error [cm/s]

zero positivenegative

–4 –0.5 0 0.5 4

1

Level error [cm]

zero positivenegative

–5 –4 0 4 5

1

1st Set of Membership Functions

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

Level error [cm]

zero positivenegative

–5 1 0 1 5

1

2nd Set of Membership Functions

Valve control signal [%/s]

no

chan

ge

ope

n fa

st

clos

e fa

st

–30 –20 –10 0 10 20 30

1 o

pen

slow

clos

e slow

Rate of level error [cm/s]

zero positivenegative

–4 –0.5 0 0.5 4

1

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

Level error [cm]

zero positivenegative

–10 –4 0 4 10

1

3rd Set of Membership Functions

Valve control signal [%/s]

no

chan

ge

ope

n fa

st

clos

e fa

st

–30 –20 –10 0 10 20 30

1 o

pen

slow

clos

e slow

Rate of level error [cm/s]

zero positivenegative

–4 –0.5 0 0.5 4

1

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Solution: Homework 8 (Cont.)Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

Fuzzy P Controller

u+–

e r y

Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

Fuzzy PD Controller

u+–

e ry

Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

Fuzzy PID Controller

ue r y+–

• Weakness: too many rules

Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

Fuzzy PD+I Controller

r+–

eyDu

Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

r u+–

e y++

Du

Fuzzy PD+I Controller

Fuzzy ControlFuzzy Logic

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PID-like Fuzzy Controllers

Fuzzy PD+I Controller

r u+–

e y++

Fuzzy ControlFuzzy Logic

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End of the LectureFuzzy ControlFuzzy Logic