Improving the performance of lifts using artificial intelligence techniques

Abstract

(Uncorrected OCR) Abstract of thesis entitled

Improving the Performance of Lifts Using Artificial Intelligence Techniques

submitted by

Wong King Sau

for the degree of Doctor of Philosophy

at the University of Hong Kong

in August 2003

An elevator group control system manages multiple elevators to serve hall

calls in a building. Most elevator group control systems need to recognize the traffic

pattern of the building and then change their control algorithms to improve the

efficiency of the elevator system. However, the traffic flow in a building is very

difficult to be classified into distinct patterns. Traffic recognition systems can

recognize certain traffic patterns, but mixed traffic patterns are difficult to be

recognized.

The aim of this study was therefore to develop improved duplex elevator

group control systems that do not need to recognize the traffic pattern. A fuzzy logic.

control unit and genetic algorithms control unit were used. A fuzzy logic control unit

integrates with the conventional duplex elevator group control system to improve

performance especially in mixed traffic patterns with intermittent heavy traffic

demand. This system will send more than one elevator to a floor with heavy demand, . according to the overall passenger traffic conditions in the building.

The genetic algorithms control unit divides the building into three zones and assigns an appropriate number of elevators to each zone. The floors covered by each zone are adjusted every five minutes. This control unit optimizes elevator group control by equalizing the number of hall calls in each zone, the total elevator door opening time in each zone, and the number of floors served by each elevator.

Both of the control units were tested by a simulator in a computer. The performance of the elevator system is given by indices such as average waiting time, wasted man-hour, and long waiting time percentage. The new performance index "wasted man-hour" indicates the total time spent by passengers in a building waiting for the lift service. Both proposed systems perform better than the conventional duplex control system.

(An abstract of 297 words.)

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Signed _

Wong King Sau