管内空気柱の音響周波数変化を利用した変位の精密測定 : 電気音響式非接触変位センサ

概要

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A new displacement measuring method using variations in sound frequency and length of an air column in a closed resonant pipe has been investigated. This noncontact displacement sensor is oscillated by the feedback loop, which is composed of a speaker, microphone and phase-locked loop. The sound pressure takes the largest value at the resonant frequency. The displacement of the measuring object corresponds to the impedance of one end of the air column. Thus the displacement of the measuring object has good correspondence to the resonant frequency of the acoustic system. The original resonant point is measured by transfer function from the FFT analyzer. An electrical analogy is adopted for theoretical analysis of the acoustic system. The results of the calculation and experiments coincide significantly.
一般社団法人日本機械学会の論文
1992-11-25