An approach using active structural acoustic control for the reduction of structure-borne road noise

Abstract

The reduction of the structure-borne road noise inside the cabin of an automobile is investigated using an Active Structural Acoustic Control (ASAC) approach. First, a laboratory test bench consisting of a wheel/suspension/lower suspension A-arm assembly has been developed in order to identify the vibro-acoustic transmission paths (up to 250 Hz) for realistic road noise excitation of the wheel. Frequency Response Function (FRF) measurements between the excitation/control electrodynamic shakers and each suspension/chassis linkages are used to characterize the different transmission paths that transmit energy through the chassis of the car. Secondly, a FE/BE model (Finite/Boundary Elements) was developed to simulate the acoustic field of an automobile cabin interior. This model is used to predict the acoustic field inside the cabin as a response to the measured forces applied on the suspension/chassis linkages. Finally, an implemented optimal active control algorithm using a feedforward structure to perform the simulation of an optimal active structural acoustic control (ASAC) by using experimental and numerical FRFs is presented. The control approach relies on the use of an electrodynamic actuator to modify the vibration behavior of the suspension and the automotive chassis such that its noise radiation efficiency is decreased. To predict the noise level reduction inside the passenger compartment, the measured FRFs of a control actuator, connected to the lower suspension A-arm, have been implemented by using the optimal active control algorithm in MATLAB ª . Its contribution to noise reduction has been evaluated in term of acoustic radiation efficiency, as measured by the sound pressure level (SPL) located at the driver's head.