HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Artificial Intelligence, Fuzzy Logic and ControlTable 6-4. Antecedent and Consequent Blocks for Fuzzy TemperatureControl————————————————————————————————Antecedent BlocksConsequentAntecedent Membership Logical Product BlocksFunctionsMinimum————————————————————————————————Rule 1 0.7 PM 0.7 AND ZE 0.8 0.8 = 0.7 THEN PM 0.7Rule 2 0.3 PS 0.3 AND PS 0.2 0.2 = 0.2 THEN PS 0.2Rule 3 0.3 PS 0.3 AND NS 0.0 = 0.0 THEN ZERule 4 NM 0.0 AND ZE 0.8 0.8 = 0.0 THEN NMRule 5 NS 0.0 AND NS 0.0 = 0.0 THEN NSRule 6 NS 0.0 AND PS 0.2 0.2 = 0.0 THEN ZERule 7 ZE 0.0 AND ZR 0.8 0.0 = 0.0 THEN ZE————————————————————————————————Key:NG NegateNL Negative LargeNM Negative MediumNS Negative SmallPM Positive MediumPS Positive SmallZE Zero————————————————————————————————There are seven rules listed, but fewer can be used. When fewerrules are used, the function becomes simpler, but control is not assmooth.A membership curve is used for logical summing. This can take atriangle shape, S, Z, bell shape or trapezoidal. The output depends onhow the individual curves overlap and it determines the type and degreeof action required.Rules can be written to include:• the difference of the temperature from the setpoint,• the rate at which the temperature is changing.©2001 by The Fairmont Press, Inc. All rights reserved.