スマートセンサを用いた音響放射パワーのアクティブ・コントロール : パワーモードと音響放射パワーについて

This paper considers the problem of sensing structural vibration to provide an error signal to adaptive feedforward control systems implemented to globally attenuate both structural and acoustic disturbances. It is shown that designing a control system which simply aims to minimize structural vibration is not necessarily the best approach, particularly in structural/acoustic problems. Rather, by considering the governing equation of the global error criterion of interest, it is possible to derive orthogonal groups of structural modes which contribute to the error criterion as a set. It is these orthogonal groupings which should be sensed as an error signal by an adaptive feedforward control system (and minimized in amplitude), a task which is easily accomplished using shaped piezoelectric polymer film sensors. Specific examples relating to the minimization of radiated acoustic power of a simply supported plate are given, showing that the use of a vibration-based error signal is a practical alternative to the use of an acoustic signal.