Abstract
Measurement of natural vibration of acoustic space is effective for noise reduction in the cabin room of vehicle (e.g. auto-mobile, railroad car and so on). In general, multi-point excitation is useful to measure natural vibration of three-dimensional acoustic space with high damping on boundary surface. However, multi-point excitation needs adjustment of amplitude and phase for each actuator. Thus, multi-point excitation is difficult to implement. In this paper, the measurement technique of natural vibrations of acoustic space by multi-point excitation using decentralized control with local feedback control is proposed. Local feedback control generates force in the direction of motion, which had been presented by authors. Firstly, an acoustic excitation system that cancels the influence of damping in acoustic space by local feedback control is developed and the basic performance of it is verified. Secondly, the feasibility of multi-point excitation using decentralized control with local feedback control is verified. Four acoustic excitation systems with feedback control synchronize via natural vibration. Thus, multi-point excitation is realized without adjustment of amplitude and phase. Finally, it is shown that transfer function by multipoint excitation can be measured by decentralized control with local feedback control. Through the experiments, it is considered that acoustic excitation system has no limitation on the number of installations and has extensibility for higher-order mode excitation.
