| Summary: | 碩士 === 國立中興大學 === 生物產業機電工程學系所 === 107 === In the automatic and precision agriculture age, a grain moisture content measurement system that could measure rapidly for avoiding the toxin in the grain during the drying and storage process is an important issue. In this study, a grain moisture content measurement system was designed and developed by combining a dual-probe frequency domain reflectometry (FDR) and Latte Panda micro-computer for measuring the grain moisture content. This system is capable of measuring the moisture content of three kind high economic value grains which are peanuts, food corns and animal corns in Taiwan. The relative dielectric constant of these grain samples can be measured by this system and be transformed to the moisture content by the calibration curve. The affecting factors of the relative dielectric constant measurement will be discussed and studied in this work. Furthermore, the calibration curve between the measured relative dielectric constant and grain moisture content has been estimated and analyzed. After optimizing the grain calibration curves, the coefficient of the calibration curves has been used in this FDR system to measure the moisture content during the drying process in the factory and comparing with other commercial grain moisture content measuring instuments.
As the experimental results shows, the relative dielectric constant measured in high temperature 50oC is higher than it measured in room temperature. The different measured relative dielectric constant is 1.8 which will not effect the accuracy of the calibration curve. For the applied pressure experiment, the results show the higher accuracy and repeatability of the calibration curve can be obtained when the measuring grain sample were in the pressured state. This is resulted from the unstable air volume between the grain sample is influence to the measured relative dielectric constant. When the grain sample was under pressure the air volume decreased and become a stable volume. To get the calibration curve experiment, three calibration curves of peanuts, food corns and animal corns have been estimated. The coefficient of determination of these three calibration curves are 0.935 for peanut, 0.898 for food corns and 0.834 for animal corns, respectively. Besides, this grain moisture content measurement system was integrated with the automatic compaction system and auto-loading system successfully for achieving the automatic requirment. This automatic measurement system is able to auto-loading the grain sample and compacting the pressure into the grain sample for the high accuracy grain moisture content measurement. This prompt wide measurement range and high accuracy of moisture content measurement system would be satisfies the business requirement.
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