Active Noise Control of a Moving Evaluation Point in One Dimensional Acoustic Field (3rd Report, Proposal of Time-delay Separation Method in the Secondary Path Identification)
Hiroshi IIDA, Mitsuru NAKAZAWA, Sekiya KOIKE · TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C · 2006
Active noise control of a moving point has been examined in our previous papers. The feature of the model is that the transfer characteristics between the noise control source and the evaluation point (aimed noise reduction point) change with the movement of the evaluation point. Real time character identification algorithm have been introduced to handle the problem. However, the convergent algorithm used in the identification works effectively only when the system is stationary, and this is one of the reason that the identification accurcy decreases when the speed of the evaluation point increases. Besides, the evaluation point moves during the identification process of the calculation and it can cause discrepancy between identification results and the real system. We propose new technique where transfer characteristics are divided into time delay factor and main components. Once the characters are divided, the change of transfer characteristics caused by the movement appears mostly in time delay factor, and since it is the function of the location, it is easy to get the delay factor. Applying this idea, one can expect remarkable improvement in the identification. This method is examined numerically and experimentally in this paper.