Active Noise Control for Automobiles Based on Least Squares Algorithm

The purpose of this paper is to propose an algorithm for active noise control (ANC) using the recursive least squares (RLS) algorithm. As a main algorithm for ANC, the multiple error filtered-x LMS (Mefx-LMS) algorithm has been used for its simplicity. However, the Mefx-LMS algorithm has a problem of the convergence speed in the case of the broadband noise as the road noise which is one of the passenger compartment noises in a car running on rough roads. This problem is caused by the ill-conditioning of the input autocorrelation matrix. In the ANC for the road noise, many accelerometers used as the input signals are necessary for a high multiple coherence. Using many input signals also causes a cross-correlation among the input signals. The ill-conditioning is mainly brouht about by the cross-correlation. In order to solve this problem, the Mefx-RLS algorithm is considered. By computer simulations, the RLS algorithm has proved to be more effective than the LMS algorithm in the convergence speed for cross-correlated input signals.