Application of the Impulse Excitation on the Grading ofthe Internal Quality of Pineapple

摘要

The traditional farmers always used the finger or a soft plastic rod knocked thepineapple to judge the quality by the flapping sound response without damage the fruits. Thepurpose of this research is to develop an automatic detection method to judge pineappleinternal quality and to effectively apply this method on the development of the automatic gradingquality system of pineapple.First of all is to according to the traditional striking method then design the appropriate strikingmechanism. Then the impulse excitation method was used by an accelerometer to acquire theacoustic signal when the pineapple was struck. The signal was analyzed with " Matlab" softwareand the signal process method which included the main peak frequency of frequency domainobtained from " FFT", the analysis of signal with wavelet transfer method for the ill pineapple.From the experimental results, the main peak frequency of solid pulp sound and ill soundpineapples are greater than 315Hz, and the drum sound pineapple is less than 315Hz whichwere decided in the research. The wavelet transforming energy' s index is below 3.8 for solidpulp sound and drum sound pineapple, and the ill sound pineapple is over 3.8. Finally, the mainpeak frequency of 315Hz was used as a standard criterion to judge either the solid pulp soundpineapple or drum sound pineapple. The other hand the wavelet transforming energy' s index3.8 was used as a standard criterion to judge the ill sound pineapple. According to this criterionand do some extra experiments which has shown that the error to judge the ill pineapple by afarmer is 11.76% but 4.4% by this research. It means this research judge the ill pineapple isbetter than that of the traditional farmer.