同心圆柱环型电容式肥液浓度传感器设计与试验  

Design and experiment of concentric cylindrical capacitive sensor for liquid fertilizer concentration

作　　者：马泽宇[1] 张建阔[1] 李加念[1] 吴昊[1] MA Ze-yu;ZHANG Jian-kuo;LI Jia-nian;WU Hao(Faculty of Modern Agricultural Engineering,Kunming University of Science and Technology)

机构地区：[1]昆明理工大学现代农业工程学院,云南昆明650500

出　　处：《传感器与微系统》2018年第3期91-94,共4页Transducer and Microsystem Technologies

基　　金：国家自然科学基金青年科学基金资助项目(51509121)

摘　　要：设计了一种同心圆柱环型电容式肥液浓度传感器,主要由稳压器、10MHz有源晶振、施密特触发器、电容传感器和真有效值检测器组成,检测结果以直流电压形式输出。在8×10^(-1)~1×10^(-3)mol/L浓度范围内,配置一系列待测肥液对传感器进行了试验:1)标定试验结果表明传感器输出电压与浓度对数呈线性负相关,决定系数R^2>0.987;2)温度变异性试验结果表明传感器输出电压与肥液温度呈线性正相关,其决定系数R^2=0.984 17;3)稳定性试验结果表明同一浓度下连续测量10 h内测量最大差值为0.000 3 mol/L,传感器稳定性良好;4)验证试验结果表明最大检测误差为9.8%。满足在线检测的实际应用要求。Design a concentric cylindrical capacitive sensor to detect fertilizer solution concentration,which consists of voltage regulator,10 MHz oscillator,Schmitt trigger,capacitance sensor,and true root-mean-square（ RMS） detector. Test results is output in the form of DC voltage. In concentration range of 8 × 10^-1- 1 ×10^-3 mol/L,take a series of experiments by using a series of fertilizer solution to test sensor： 1） calibration experiments show that output voltage of sensor have linear negative relationship with fertilizer solution concentration,the decision coefficient is R^2 0. 987; 2） results of temperature variabilily test show that output voltage of sensor has linear positive relationship with temperature of fertilizer solution,the decision coefficient is R^2= 0. 984 17; 3） results of stability test show that the biggest difference value in 10 h that under the same concentration of liquid fertilizer is 0. 000 3 mol/L,stability is good; 4） validation test show that the maximum detection error value is 9. 8 %. therefore,this sensor can meet application requirement of detection of fertilizer solution concentration in practical engineering.

关 键 词：肥液浓度 介电常数 同心圆柱环型 电容传感器 真有效值 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]