种子含水率在线测量系统

On-line Measuring System of Seed Moisture Content

根据种子含水率的测量要求,研制了一种可同时测量电容、质量和温度3个参量的装置和测量电路。该测量系统的机械装置由2个同心圆筒组成,内筒的旋转运动实现被测种子的动态喂料。采用抗寄生电容效应的开关电容电路测量上、下极板之间的电容;下极板同时也是称量平台;温度传感器测量种子的温度。3个测量值经A/D转换电路以数字量输出。分别用3个电路单独测量已知的电容、质量和温度,以及不同温度和相对湿度条件下对电容测量值的影响,并据此分析了各测量单元的精度、可靠性和可行性。

An on-line measuring system of seed moisture content is developed in this paper. The mechanical system is mainly composed of two horizontal concentric cylinders. The inner cylinder rotates and continuously delivers seeds into the measuring position between the two cylinders. A stray-immune switching circuit is employed to measure the capacitance of the two steel plates. The lower steel plate also serves as the platform of the weighing unit in the system. The temperature is sensed by precise thermal transducer. The measured information of the capacitance, weight and temperature is output in digital format via A/D converter. Experiments are made upon the three units with known capacitance, weight and temperature respectively, and the influence of temperature and atmosphere humidity to the capacitance is measured also. The accuracy, reliability and feasibility of the system are therefore evaluated.