局所フィードバック制御を用いた分散制御による音響空間の固有振動の計測

抄録

Natural vibrations of acoustic space expand noise. Measurement of natural vibration is effective to reduce noise based on noise generation mechanism. Acoustic space has many natural vibrations in the noise frequency band. Multi-point excitation is useful for measuring natural vibration, which has mixed modes and high damping. Furthermore, it is necessary to cancel the influence of dumping to excite the modes individually. In this study, the new measurement principle of natural vibrations of acoustic space by multi-point excitation using decentralized control with local feedback control is proposed. An excitation system with local feedback control excites natural vibration without frequency adjustment and cancels damping in acoustic space. Excitation systems with decentralized control can have multi-point excitation without any adjustment of amplitude and phase each other. The proposed acoustic excitation system consists of a speaker, a microphone and a local feedback controller. The controller generates negative damping according to the sound pressure detected by the microphone and feeds it to the speaker. Firstly, it is confirmed that one acoustic excitation system is self-excited at resonance frequency and some resonance peak of the transfer function is sharpened by canceling the effect of damping. Secondly, multi-point excitation using decentralized control using four acoustic excitation systems is performed to excite many modes. All supposed modes are excited without adjustment of the excitation systems according to mode such as amplitude and phase. Finally, it is confirmed that acoustic excitation system has no limitation on the number of installations and has extensibility for higher-order mode excitation.