| Grain moisture monitoring online is absolutely necessary in the grain storing safely, and also the core technology which restricts grain drying system. On the concrete condition of grain moisture measurement, the author makes a thorough study on the technology. Through the analysis on dielectric properties of grain, using method of capacitive measurement, the author designed a set of capacitive moisture measurement system for grain online.Starting from stability and sensitivity of system of signal acquisition, the author focuses on the design of system of hardware device, and finally completed the experimental platform of moisture measurement system for grain online, and verified the feasibility of plan through the experiment preliminarily. The main research works are as follows:Firstly, understand principle of capacitive moisture measurement system for grain online and the development of this technology in the system furtherly, induce difficulties in the technology which needs paying attention.Secondly, understand the design ideas of hardware system, choose the optimal signal acquisition circuit after comparing different circuits, so as to improving the sensitivity and stability of system. Then establish a set of stable hardware platform of real-time monitoring and can work basically.Thirdly, study Freescale microcontroller, Codewarrior and Qt. Develop the software platform of system which initializing peripheral devices, controlling signal acquisition, display data real-time etc.Fourthly, put forward the related data processing algorithm for the random error in system error which removes the measured bulky error effectively and smooths the waveform.Finally, verify the stability of hardware system performance through comparing and analying repeatly. Fitting out curve of voltage measured varing with temperature, moisture, compactness and analyze the error. |
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