Active control of acoustic power radiated from a vibrating planar structure using smart sensors (Acoustic power suppression using adaptive feedforward control)

This study deals with the problem of sensing structural vibration to provide an error signal to an adaptive feedforward control system, which aims to globally attenuate both structural and acoustic disturbance. This paper demonstrates the validity of a newly proposed ''smart sensor'' as a distributed parameter sensor made of PVDF film which is designed to measure an acoustic power mode of the total acoustic power radiated from a vibrating plate. Firstly, with a PVDF distributed parameter sensor attached on the entire surface of the plate, the formulas for sensing the j-th acoustic power mode are derived. Then, by considering the practicability of implementing the smart sensors, alternative formulas for sensing the acoustic power mode are derived for a strip-type smart sensor. The characteristics of the smart sensors optimally shaped for measuring the acoustic power modes are also shown. Moreover, based upon an adaptive feedforward control with the filtered-xLMS algorithm, an experiment was conducted to demonstrate the minimization of the acoustic power radiated from a vibrating plate.