APPLICATION OF ACTIVE NOISE CONTROL TO AN ELEVATOR CABIN J. Landaluze, I. Portilla, N. Cabezón, A. Martínez and R. Reyero IKERLAN Technological Research Center Control Engineering Department P.O. Box 146, E-20500 Arrasate-Mondragón, Spain E-mail: jlandaluze@ikerlan.es. Phone: +34-943712400. Fax: +34-943796944 Abstract: The elevators constructed today are increasingly fast and have a high level of comfort. However, this increase in speed means a higher level of noise inside the cabin, and this noise is normally compensated by passive means, that is, by improving the cabin's insulation. Low frequency noise persists, however, and it should be dealt with by active means. This article describes the practical application of Active Noise Control to an elevator cabin, greatly reducing the level of noise in the whole area. The results obtained are an advance towards the integration of Active Noise Control in elevators, and its commercialisation. Copyright  2002 IFAC Keywords: Active noise control, LMS algorithm, feedforward control, adaptive digital filters, multichannel controllers. 1. INTRODUCTION It is a well-known fact that passive noise compensation methods are not effective for low frequency noise of less than 200 Hz, and that Active Noise Control methods are necessary for these frequencies. The combination of both methods provides the optimum solution in a large number of cases. The development of digital signal processors (DSPs) enables adaptive filtering algorithms to be used, and these considerably improve the performance and operations of the active control systems (Kuo and Morgan, 1996). Currently, the continual advances in these processors and their decreasing cost favour the development of applications, and systems for cars (Eppli and Stroup, 1998; Finn and Stroup, 1998), airplanes, industrial environments, heating, air conditioning, etc. are now available on the market. Although most commercial applications are based on the application of Active Control to ducts (or to cases which can be considered as equivalent to ducts) due to their simplicity and the spectacular results which may be obtained, the application of Active Control to three-dimensional enclosures, generally of reduced dimensions, is being increasingly studied (Hansen, 1997). Active Noise Control is acquiring great importance in top-of-the-range elevator applications. The elevators constructed today are increasingly fast and have a high degree of comfort. This increase in speed implies an increase in noise, and a certain reduction in passenger comfort as a result. Passive Noise Control methods have been used for some time in high-comfort elevators, and as a result the remaining noise in the cabin is mainly low-frequency noise. Active Control methods are therefore appropriate for compensating this type of noise. IKERLAN, which is a research center located in the Basque Country, and ORONA, an important European elevator manufacturer, have been working together on the comfort improvement of elevator cabins. This article describes the application of Active Noise Control to a commercial elevator cabin. Although the tests were carried out in the laboratory, Copyright © 2002 IFAC 15th Triennial World Congress, Barcelona, Spain