基于微波谐振器的谷物湿度检测系统

MICROWAVE MEASUREMENT SYSTEM OF GRAIN MOISTURE CONTENT BASED ON MICROWAVE RESONATOR

设计和研制一种能连续测量谷物湿度的微波检测系统。提出利用微波谐振器的干扰特性测量谷物的湿度,并设计专用于谷物湿度检测的中心开通孔的微波谐振器。当谷物颗粒通过微波谐振器的中孔时,其质量和湿度都令谐振器的谐振频率产生偏移和功率衰减,谷物的质量和湿度两者所引起的谐振频率偏移和微波功率衰减是相对独立的,在同一湿度下谷物的质量仅仅与微波功率的衰减量有关。因此在得到谐振频率的偏移量和微波功率的衰减量后,就可以计算谷物的湿度。在大量试验的基础上,对试验数据进行模糊聚类,从而对微波谐振器的频偏和功率衰减特性进行建模,据此设计并研制了谷物湿度的微波连续检测系统。试验调试表明:该检测系统适宜于谷物的连续湿度检测,检测精度达到92%以上。

A new microwave measurement method for moisture content of grain is proposed. According to this method, a measurement system is designed for grain moisture content continuous measurement. In this system, moisture content can be measured by a specially designed microwave resonator which has a center hole. When grain passes through the center hole, its density and moisture will cause resonant frequency excursion （RFE） and microwave attenuation （MA） of the resonator. Under the same moisture, density is only related to MA. If RFE and MA are detected, we can calculate moisture content of grain, the change of density would not affect the calculating result of moisture content. In order to get high accuracy, a center-certain fuzzy clustering algorithm is proposed. According to the response characteristic of microwave resonator and the fuzzy clustering algorithm, we designed a high accuracy microwave measurement system which can measure grain moisture content in real-time. Exporimental results show that the measurement system has high accuracy. Its accuracy is varied from 92 percent to 96 percent in different months.