Design Of Buckwheat Moisture Rapid Detection System

Shanxi's small grains are known at home and abroad for their "green,nutrition and health",and are known as "small grains kingdom".Buckwheat is one of the main small grains planted in Shanxi Province.Buckwheat is rich in nutritive value and contains a variety of nutrients lacking in staple food such as wheat and corn,which is an important health food.The ceaseless rise as people living standard,people more and more favour at green food,the small miscellaneous grain that is represented with buckwheat becomes the first selection of masses,because this is right,the quality of buckwheat also had higher requirement.In the processing,storage and transportation of buckwheat,the quality and moisture content are closely related.High moisture content will lead to mildew of stored buckwheat,and low moisture content will destroy the nutrition structure of buckwheat and reduce the quality of buckwheat.Therefore,it is important to detect the moisture content of buckwheat quickly and accurately.The standard test method of grain moisture content mainly uses the electric oven drying method,and the result measured by this method is of high accuracy,but the actual operation is not only time-consuming and laborious,but also unable to achieve rapid and continuous measurement.At present,most of the moisture detectors on the domestic market take wheat,corn and other staple grains as test objects,and there are few exclusive moisture rapid detectors for buckwheat and other small grains.Therefore,it is necessary to develop an economical and reliable buckwheat moisture detector.The change of water content of buckwheat will cause the change of dielectric characteristic,and the change of dielectric characteristic will cause the change of detection capacitance.Therefore,the moisture content of buckwheat can be calculated indirectly by measuring the change of capacitance.Based on the dielectric properties of buckwheat,this paper designs a kind of rapid moisture detector for buckwheat by measuring the capacitance.The main research contents are as follows: 1.The effect of measured frequency and moisture content on dielectric properties of buckwheat was studied.Conclusion:In the frequency range of 100 HZ ~ 1.5mhz,the relative dielectric constant of buckwheat decreases with the increase of measurement frequency.When the frequency is less than 10 KHZ,the relative dielectric constant decreases significantly.When the frequency is greater than 10 KHZ,the change trend of relative dielectric constant tends to be gentle.The dielectric constant curve of buckwheat with high water content is steeper than that of buckwheat with low water content.Based on the relation between the relative dielectric constant of buckwheat and frequency and moisture content,the moisture measurement model was established.To simplify the model variables,the variable optimization algorithm(SPA)and genetic algorithm(GA)were used to extract the modeling sensitive frequencies and reconstruct the modeling.2.Based on the sensitive frequency of water model,a portable buckwheat moisture detector was designed by taking MSP430F149 microcontroller as the core,combining with cylindrical capacitance sensor,AD5933 impedance measurement chip and DMTFT-28 TFT touch screen.3.Ten buckwheat samples with different moisture content were prepared.The moisture content was measured by buckwheat moisture detector at room temperature.Results show that compared with 105 ? constant weight method,this paper design the buckwheat moisture detector testing relative error is within ±9%.