Active noise control algorithm for road noise in vehicle on changing pavement

The noise in vehicle is an important issue though it's weakly related to original purpose of vehicle compare to handling, safety, and driving. Especially, the interior noise keeps stimulating passengers in driving condition and it cannot help being very sensitive to them so that all motor companies organize team for NVH (Noise Vibration Harshness) and manage the total sound of vehicle. The interior noise can be categorized as engine, road and wind noise. Among them, road noise has stood out after engine noise is relatively reduced. Even it can be more crucial in electric vehicle. It is broadband noise generated by vibration of tire on irregular road surface and irritate passengers while driving. For this, there have been researches about redesign of tire, suspension, or cabin based on structure-borne noise analysis and passive methods that sound absorbers are placed in the transfer path. However, the redesign can deteriorate other performances, such as handling, riding, and fuel efficiency. Recently, active noise control methods have been introduced as an alternative. Though many algorithms are proposed, the practical application is still not widespread. One of important issues for practical application is presented that the required weight filters are frequently changed as the driving condition is changed. Accordingly, a hybrid ANC algorithm is proposed. It is operated as feedforward FXLMS algorithm with slow convergence in stable mode. Meanwhile, at the moment when the change of driving condition is detected, the weight filter is converted to the nominal weight filters, and simultaneously the algorithm starts to find the optimal filters with the recently measured signals. After a while, the optimal filters are achieved and smoothly applied to reduce the noise in changed driving condition. Numerical simulations are implemented and verified the feasibility of proposed algorithm.