A two-layer adaptive active structural noise control system

Vibrating plates have been gaining increasing interest for active noise reduction or isolation systems. Unfortunately, they are much harder to control than loudspeakers. Plates have multimodal response with high variations of amplitude response. To effectively excite multiple vibration modes multiple actuators are usually needed. Using multiple actuators mounted on a single plate significantly increases the number of control signals to be worked out. This could be a severe problem for active control systems with multiple vibrating plates. Such system would have a large number of secondary paths and necessity to adapt many control filters. However, secondary paths for the same vibrating plate are not fully independent. In this paper a lower-layer single-input multiple-output controller is designed first for the vibrating plate to be seen as a single-input single-output plant of equalized frequency response. Then, a higher-layer active controller is designed to reduce noise. The control system is experimentally verified and obtained results are reported.