四端法土壤电导率传感器恒流源设计与试验  

Design and Experiment of Constant Current Source of Four-terminal Conductivity Sensor

作　　者：陶毅 孟繁佳[1] 盛文溢 TAO Yi;MENG Fanjia;SHENG Wenyi(Key Laboratory on Modern Precision Agriculture System Integration Research, Ministry of Education, China Agricultural University, Beijing 100083, China)

机构地区：[1]中国农业大学现代精细农业系统集成研究教育部重点实验室,北京100083

出　　处：《农业机械学报》2020年第S02期415-420,共6页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家重点研发计划项目(2018YFD010100202);国家自然科学基金项目(31401294)。

摘　　要：土壤信息对于指导农业生产有着极为重要的作用,土壤电导率反映了土壤含水量、盐分、粘粒含量和类型等土壤信息,准确获取土壤电导率对于实现农业精细化生产意义重大。在各种土壤电导率测量方法中,四端法因其成本低、精度高、测量快速和操作简便而大量应用于实际测量;恒流源是四端法测量仪器的重要组成部分,其性能直接决定着测量仪器的精度以及测量范围。本文对比了3种恒流源对测量仪器测量性能的影响,发现采用Howland恒流源的四端法测量仪器高电导率测量能力强而低电导率测量范围较小,测量精度最高;采用改进型Howland恒流源的四端法测量仪器低电导率测量范围有所扩大,测量精度良好;采用基于差动放大器的恒流源的电导率仪低电导率测量范围最大,高电导率测量范围较优,测量精度良好。Soil information plays an important role in guiding agricultural production.Soil electrical conductivity reflects soil information such as soil moisture,salinity,clay content and type,it is significant to obtain soil electrical conductivity accurately for realizing agricultural fine production.Among all kinds of soil conductivity measurement methods,the four-terminal method is widely used in practical measurement because of its low cost,high precision,fast measurement speed and simple operation,its performance directly determines the accuracy and measuring range of the measuring instrument.The effect of three constant current sources on the measuring performance of the measuring instrument was compared.It was found that the four-terminal method using Howland constant current source had the best measuring accuracy and the high measuring ability,but the low measuring range was small.The measuring range of low conductivity by using improved Howland constant current source was enlarged and the measuring precision was good.The measuring range of low conductivity by using constant current source based on differential amplifier was the largest,the measuring range of high conductivity was better and the measuring accuracy was good.

关 键 词：土壤电导率 恒流源 四端法 传感器 

分 类 号：S151.9[农业科学—土壤学]