Small-size watermelon ripeness detection method based on dielectric frequency spectrum

Abstract

The invention relates to a small-size watermelon ripeness detection method based on a dielectric frequency spectrum. The small-size watermelon ripeness detection method comprises the following steps of: placing a watermelon to be detected into a detection device formed by three sets of electrodes which are tightly stuck to the surface of the watermelon; applying alternating electromotive force among the electrodes; measuring a dielectric response signal of the watermelon to the alternating electromotive force; carrying out data processing on a dielectric frequency spectrum signal; judging the ripeness of the watermelon through a clustering analysis; meanwhile, collecting temperature information in the detecting process and carrying out temperature compensation in the data analyzing process. According to the method disclosed by the invention, dielectric spectrums with different frequencies are used for realizing the nondestructive detection, and the problem that the measurement is inaccurate, caused by only using a single frequency, is overcome; meanwhile, the dielectric spectrum scanning is carried out at a plurality of angles so that the measuring error caused by individual difference is reduced; the electromagnetic interference is eliminated and the high-frequency interference to a collection circuit by an exciting circuit is eliminated; a temperature compensation algorithm is added and the influence on the measurement accuracy by temperature variation is eliminated.

Description

technical field [0001] The invention belongs to the field of measurement, and in particular relates to a maturity detection method based on a dielectric spectrum. Background technique [0002] The maturity of watermelon is an important basis for determining the best picking period and grading of watermelon. Non-destructive testing of watermelon maturity plays a very important role in improving the quality and economic value of watermelon. At present, melon farmers judge the degree of watermelon mainly based on experience based on the sound and vibration of knocking. This method has relatively large errors due to individual differences in people, and the correct rate of judgment is low, and it cannot be standardized. A traditional, recognized and objective test method to describe the ripeness of watermelon is to measure the sugar content of its juice. But this method needs to cut the watermelon, which is destructive, and it is impossible to test a large sample, let alone tes...

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Problems solved by technology

However, this method needs to cut the watermelon, which is destructive, and it is impossible to detect large samples, let alone test one by one

[0003] Some researchers have developed a new technology and equipment based on acoustics (He Dongjian. Non-destructive determination of fruit quality, Grain and Oil Processing and Food Machinery, 1992 (6): 37-40; He Dongjian et al. Research on the characteristics of watermelon hitting sound waves, Journal of Northwest Agricultural University, 1994 , 22(3): 105-107.) or shockology (Hu Shengxi. Feasibility Discussion on Measuring Watermelon Ripeness Using Vibration Response Spectrum, Journal of Bayi Agricultural College, 1991, 14(2): 73-75) Measuring the maturity of watermelon, by detecting the sound frequency or vibration spectrum after tapping the watermelon to detect the maturity, has achieved certain results, but these methods are greatly affected by the growth state of the watermelon, and some people use the dielectric constant method To detect the maturity of watermelon (Nelson S O, Guo Wenchuan, Trabelsi S.Study of Fruit Permittivity Measurements for Quality Detection, IEEE Instrumentation and Measurement Technology Conference. New Jersey: IEEE, 2008: 1009-1019.), in terms of soluble solids content and sugar content are used as quality indicators of watermelon, the results show that the prediction accuracy is not high

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