Production of a remote measuring system of fruit softening using laser beams and an acoustic wave

结果表明：(1)用激光多普勒测振仪精确测量了猕猴桃果实振动时从果实表面反射的激光的多普勒频移。(2)监测到了5~2000赫兹的水果振动幅度，并检测到几个共振峰。当苹果果实软化时，共振频率下降，但在其他水果中没有观察到这种下降，这表明共振频率不是果实软化的最佳指标。(3)当果实软化时，观察到声波的移动。桃子、梨和柑橘果实的软化与相移有很好的相关性。(4)相移反映了柑橘果实内部的组织结构。(5)振动台上的加速度计与激光多普勒测量机之间的差动信号反映了从测试结果中得到的精确的振动信号。从这些结果来看，基于激光的水果软化测量系统优于其他报道的方法，是一种很好的远程和非破坏性的定性和定量评价水果软化程度的方法。虽然我们无法生产出水果分选机的原型，但松下-Kotobuki电子工业株式会社仍在研究评估水果质地的算法。

The following results were obtained ;(1) When kiwi fruit was vibrated, the Doppler shift of laser beam reflecting from the surface of the fruit was precisely determined by a laser Doppler vibrometer.(2) Amplitude of the vibration of fruit was monitored from 5 to 2000Hz, and several resonance peaks were detected. The resonance frequency decreased when an apple fruit was soften, as reported, but the decrease was not observed in other fruits, suggesting that the resonance frequency is not the best index for the fruit softening.(3) The shift of acoustic waves was observed, when the fruit proceeds softening. There was a good correlation between the phase shift and fruit softening in peach, pear, and citrus orange.(4) The phase shift reflects the inside organization of citrus fruit.(5) The differential signal between an accelerometer attached to the stage of vibrometer and the laser Doppler measuring machine tells the precise vibration signal derived from the test fruit.From these results, the fruit softening measurement system using a laser beam is superior to any other reported method, and is an excellent remote and non-destructive method to evaluate qualitatively and quantitatively the degree of fruit softening. Although we could not produce a prototype of fruit sorting machine, the algorism for evaluating the fruit texture is still being processed in Matsushita-Kotobuki Electronics Industries Ltd.