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Automating Manufacturing Systems - Process Control and ...

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plc fuzzy - 26.3<br />

1. If (bucket is full) then (stop filling)<br />

1<br />

bucket is full<br />

0<br />

height<br />

1<br />

0<br />

stop filling<br />

a1<br />

angle<br />

2. If (bucket is half full) then (fill slowly)<br />

1<br />

0<br />

bucket is half full<br />

1<br />

0<br />

fill slowly<br />

height<br />

a2<br />

angle<br />

3. If (bucket is empty) then (fill quickly)<br />

1<br />

0<br />

bucket is empty<br />

height<br />

1<br />

0<br />

fill quickly<br />

angle<br />

Figure 26.3<br />

Fuzzy Rule Solving<br />

An example of a fuzzy logic controller for controlling a servomotor is shown in<br />

Figure 26.4 [Lee <strong>and</strong> Lau, 1988]. This controller rules examines the system error, <strong>and</strong> the<br />

rate of error change to select a motor voltage. In this example the set memberships are<br />

defined with straight lines, but this will have a minimal effect on the controller performance.

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