土壤剖面水分传感器探头仿真与试验

Simulation and Experiment on Soil Moisture Profile Sensor Probe

为准确掌握土壤墒情信息,针对农田环境下不同作物根区土壤含水率变化难以实时观测的问题,对土壤剖面水分传感器探头进行了仿真,并通过试验验证,给出了传感器探头设计尺寸的优选方案。在建立传感器探头微量化平面电容二维模型的基础上,分析了传感器探头结构变化对探头微量化平面电容周围电场强度和电容变化的影响,确定了探头结构尺寸的最优组合。当探头铜环电极外径40 mm、内径38.4 mm、轴向长度20 mm、轴向间距15 mm时,探头的灵敏性和探测范围最优。试验结果表明,本文研究的土壤剖面水分传感器测量精度为±1.42%,具有很高的稳定性和一致性。所设计的传感器探头可以根据实际测量深度需要任意组合,满足不同作物根区深度的土壤含水率测量需求。

In order to accurately grasp soil moisture content information, the problem of real-time observation of soil moisture change in different crop root areas under farmland environment is difficult to observe. The structure of probe was researched and analyzed in detail by modeling simulation analysis, and the optimal sensor structure was determined through experimental verification. Through establishing the trace amount planar capacitance probe two-dimensional model, the influence of change of sensor probe structure on the change of electric field intensity and the capacitance value around the trace amount planar capacitance probe was analyzed by using the finite element analysis, and then the probe structure was determined. The sensitivity and the detecting depth of the probe was optimal when the outer diameter of the probe copper ring electrode was 40 mm, the inner diameter was 38.4 mm, the axial length was 20 mm, and the axial spacing was 15 mm. The sensor probe can be applicable to various types of soil moisture measurement. The measurement accuracy reached ± 1.42% with better stability and consistency. The results showed that the sensor probe can be designed according to the actual measurement depth and satisfy the Soil moisture measurement requirements of the root zone of different crops.