Robust and Adaptive Feedback Noise Attenuation in Ducts

Abstract

In this brief, the attenuation of sound propagation in an air-handling duct using robust and adaptive feedback active noise control (ANC) strategies is investigated. The case of multiple narrow-band disturbances located in distinct frequency regions and the interference occurring in the presence of disturbances with very close frequencies are considered. The active control uses a loudspeaker as a compensatory system. The objective is to minimize the residual noise at the end of the duct segment considered. The system does not use any additional sensors for receiving real-time information upon the disturbances. This brief illustrates the application of the techniques for active vibration control presented by Landau et al. to this problem. A hierarchical feedback control approach will be used. At the first level, a robust linear controller will be designed taking advantage of the knowledge of the domains of variation of the frequencies of the noise disturbances. To further improve the performance, a direct adaptive control algorithm will be added. Its design is based on the use of the internal model principle combined with the Youla–Kucera parameterization of the controller. Guidelines for the design of the baseline (central) controller are provided. Both robust and adaptive controls require the knowledge of the discrete-time model of the compensation path, which is obtained by identification from experimental data. Experimental results on a relevant duct ANC test bench will illustrate the performance of the proposed methodology.