Research On Detection Technique For Grain Moisture Content Based On Weight-loss Method Correction

Grain quality and security relations with the country’s political, economic and socialstability, and play an important role in the entire national economic construction and variousother related industries. Grain moisture content is a critical factor that affecting the grainquality, and also as an important quality index that has been strict controlled by domestic andforeign food sectors. In the food processing, the moisture content will affect the physicalproperties process quality and food safety of grain and its products as it too high or too low.Therefore, the on-line measurement of moisture for grain is essential.This topic is one engineering application sub-topic of the "the study of Grain MoistureOn-line Fuzzy Control Device" which is the key scientific and technological project ofScience and Technology Department of Henan Province.Complex impedance separationdetection performs fast and online testing, but its accuracy affected by compaction, density,environment temperature, humidity, and other factors. Microwave weight loss method is aimprovement measurement of the standard measurement, but not suitable for onlinemeasurements, and the working life of magnetron is limited. This subject measured themoisture for grain by combination of complex impedance separation method and microwaveweight loss method. It fit data of capacitance values and moisture content, real-timecorrection and updates the moisture content value of fitting formula by microwave weightloss method, and to eliminate the environmental impact of complex impedance separationmeasurement, eventually realized that the measurement of moisture for grain is of online, fastand accurate. Power control circuit was designed in microwave weight loss method so thatmicrowave heating uniformity, curves estimation of the water loss is also applied to shortenthe measurement time and improve accuracy.The main research topics are as follows:1．Researching the relationship of the capacity and of the grain moisture sensor inseparation of complex impedance and how to separate the resistance and accuratemeasurement the capacitance of grain moisture sensor2．Researching the power of magnetron can be adjusted continuously in weight-loss toperform microwave heating uniformity, to avoid charring food phenomenon appears andimprove the measurement accuracy.3．Software and hardware of the moisture on-line detection device was designed in alaboratory environment. The moisture on-line detection system was established with a32-bitARM Cortex-M0microprocessor chip LPC1114F as the core.4．Researching the function of sensing capacitance and the value of grain moisture andestablishing a data fitting formula of the capacitance and grain moisture content value,performed on-line correction of fitting formula by microwave weight loss method, and realizethe measurement of moisture for grain is of online, fast and accurate.