Research On The Method Of Seed Water Content Measurement Based On Electromagnetic Induction

In the field of traditional seed water content testing,according to the “Rules for International Seed Testing” and China's "Rules for Agricultural Seed Testing",the main testing techniques include: Drying inspection with high temperature;Electronic water metering measurement;Toluene distillation method;Karl Fischer method,etc.These methods own problems more or less such as bringing damage to the seed structure,inability to test the whole,long time using,heavy weight,high cost,contact testing,and inability to reflect in real time.The paper focus on the engineering application of the principle of electromagnetic induction.For the first time,a three-coil seed water content testing method with singleexciting dual-receiving based on the principle of electromagnetic induction is proposed.By obtaining the relative dielectric constant of the seed,the relationship between the amplitude ratio and the seed water content was constructed to realize the testing of the non-contact seed water content.This overcomes the problems,such as the traditional seed water content testing cannot reflect the water content of the test object in real time,the testing time is too long,and the heating testing method destroys the seed tissue.Main research process is as follows:First,based on the theory of engineering electromagnetic field,refer to the classic Debye-cole model,a three-coil testing structure with single-exciting and doublereceiving is proposed,and a functional relationship between momentum amplitude signal ratio of AC current of two receiving coils and the seed water content is established.Second,perform simulation analysis by Matlab,50 sets of theoretical analysis values of the test results were obtained,and the quantitative relationship between amplitude ratio and seed water content was studied.In order to cope with the different dimension between the amplitude ratio,the relative dielectric constant,and the seed water content,the max-min formula is applied for data processing of normalization.Finally,a simple prototype model was produced by using reliable materials such as magnet exciting coil and PVC pipes.The experiments were carried out by using soybean seeds.The experiments were divided into systematic deviation experiments and soybean fluctuation experiments,to verify the reliability of the detection system and whether it could reflect changes in seed water content.The results of the study initially indicate: the change of seed water content can be obtained by electromagnetic detection method,and the relationship between the amplitude ratio and the relative dielectric constant of the seed is used to test the seed water content.And the standard deviation of the system after removing the error of the platform itself is 0.022,and the system stability is good.Compared with the infrared water content testing method commonly used in granaries,it has advantages in power consumption,testing time,equipment weight,equipment cost,and installation method.