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

HVAC Control in the New MillenniumFuture TrendsExpert systems open a new dimension in the way computers canbe used for HVAC. Expert systems technology is being integrated intothe architecture of many distributed control systems and networkedprogrammable controller systems. Self-tuning PID controllers use expertsystem technology. A boiler might incorporate a troubleshooting anddiagnostic expert system as part of the control system for the boiler.Expert system applications include sensor testing and validation,control system design validation, performance evaluation, diagnostics,on-line tuning and statistical control and analysis.Neural NetworksNeural networks such as expert systems, fuzzy logic, robotics,natural language processing, and machine vision, are parts of the overalltechnology umbrella known as artificial intelligence (AI). Neural networksattempt to mimic the structures and process of biological neuralsystems. They provide a powerful analysis technique for complex processingof large amounts of input/output information. They have theability to generalize or form concepts.Artificial neural networks (ANNs) are a useful information abstractionin modeling intelligence in control systems. Neural networksmay be thought of as a functional mapping of inputs to outputs usingan interconnected network of nodes. Weights are given to the node interconnectionsto achieve the desired mapping.Artificial neural networks are a cognitive information processingstructure based upon the models of brain function. It is a highly paralleldynamic system that processes information using the state response toinputs.The advantage of neural networks is in their ability to learn arbitraryfunction mapping with little or no prior knowledge about the functionitself. They provide the capability to do black-box modeling of aprocess given only the Input/Output data.These networks have proved to be robust, resilient and capable ofadaptive learning. The disadvantage is that the knowledge is implied bythe network connection weights.Neural networks have been used as virtual or soft sensors to infer©2001 by The Fairmont Press, Inc. All rights reserved.