NONDESTRUCTIVE MATURITY DETERMINATION OF DURIAN BY FORCE VIBRATION AND ULTRASONIC

Abstract

The nondestructive determination of the maturity of durian is an important process for quality control. Since durian has specific properties, such as the thickness of peel, non-uniformity of shape, roughness of prickle skin, largeness of size etc., the nondestructive determination of the maturity is hard to perform. This paper proposes two approaches for determining maturity of durian by using nondestructive vibration and ultrasonic. The appropriate vibration and ultrasonic are directly transferred through durian in the region between prickles located at the middle of durian. The measurement of frequency response from vibration of durian is done by using laser doppler. The signal measured by laser doppler is processed to extract high frequency part by wavelet transform and convert into spectrum form. The template matching is performed by correlation between the high frequency spectrum of signal and templates in order to determine the maturity of durain. To evaluate the proposed method, two prototypes of system using force vibration and ultrasonic are constructed. The experiments are performed for comparing with the results of dry-weight percentage method that is considered to be absolutely right destructive way. And the results of template matching by correlation as proposed signal processing are also compared with conventional signal processing such as vibration velocity way and elastic constants way. The results reveal that the methods using force vibration and ultrasonic with template matching are more accurate by 95% approximately.