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

Artificial Intelligence, Fuzzy Logic and ControlFigure 6-8. PID and fuzzy controlthe deviation and returns the setpoint slowly to the correct value, whilekeeping it within a range where there is no risk to overshoot.Fuzzy Feedforward ControlFurther improvements in product consistency are possible when aprocess parameter is used as an advanced warning signal. Thefeedforward input serves to change the fuel flow long before outputchanges result in environment or product. The feedforward changes arenot exact, and their influence is adjustable as in feedback control. Themethod of calculation of the final feedforward control action is similarto the calculation of feedback control action. In one application the fuzzyfeedforward control resulted in a 40% reduction in the standard deviationof the target property.Fuzzy Color SensingColor sensing can be done with fuzzy logic control. A sensor headwith light emitting diodes for red, green and blue light is used. The sensorhead also has circuitry to measure the light reflected by the object.A number of noncontact color profile measurements are taken tocompute the average color profile. These profiles are compared to a prerecordedstandard and if the deviation between the two values exceeds theprogrammed acceptable tolerance, the output signals a rejection.©2001 by The Fairmont Press, Inc. All rights reserved.