Active control of vehicle’s interior sound field by using multichannel H∞ robust controller

Abstract

The sound level inside an automobile cabin plays a major role in the passengers’ comfort. Active noise control has been widely used to reduce the sound level inside the car cabin. This article presents a design of an active and robust sound control system that can still be efficient despite the changes inside the passengers’ compartment caused by the movement of the occupants. Initially, the coupled acoustic structural analysis is done on a simplified model of an automobile cabin by using finite element and modal coupling methods. Then, the uncertainty of the sound field inside the car, due to the presence of the occupants and the displacement of their heads, is investigated. A multi input multi output robust feedback control strategy, using the H∞ method and considering the unstructured uncertainty of the acoustic structural system, is proposed to reduce the sound pressure level at the ears of all the occupants. In order to achieve performance targets in a broad bandwidth and to reduce the waterbed effect, an optimization is performed on the weight function coefficients. The results show that in the frequency range of 0–334 Hz, the controller has an acceptable performance which is robust to changes in the interior sound field.