基质含水量电导率无线检测系统及应用研究

发布时间：2017-12-27 19:42

本文关键词：基质含水量电导率无线检测系统及应用研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：在基质栽培生产中,及时掌握并调控基质的含水量、电导率和温度等参数,对作物的生长具有重要的意义。针对目前基质检测系统水分、电导等参数检测准确性、稳定性差的问题,本文基于多传感器融合技术,利用无线网络技术,研究出基质含水量电导率无线检测系统,并进行了应用试验研究。这对提高农业生产自动化程度,促进基质栽培生产科技进步具有十分重要价值和意义。本文主要研究内容和结果是:(1)基质含水量电导率传感器设计及仿真。通过对基质含水量电导率检测方法现状分析,确定了采用电容法检测含水量,采用交流“电流-电压”四端法检测电导率;针对基质不同于土壤的理化特性,为保证传感器的敏感元件与基质有良好的接触性、传感器结构简单易实现,本文统一设计含水量电导率传感器的敏感元件结构;对敏感元件结构进行ANSYS静电场仿真分析,确定敏感元件的尺寸;对含水量、电导率和温度检测电路优化设计,优化调整PCB排版布局。(2)基质含水量电导率无线检测系统构建及软件设计。基于ZigBee无线网络技术,设计了传感器节点和汇聚节点软件程序,构建基质含水量电导率无线检测系统;以虚拟仪器LabVIEW为管理平台,设计了上位机系统管理程序,在人机交互界面直观观察传感器各个节点的检测结果及其变化曲线。(3)基质含水量电导率传感器标定及温度补偿研究。设计标定试验,基于温度补偿方法,根据检测参数温度特性,温度对含水量和电导率检测结果的影响试验数据,利用回归分析方法建立基质出含水量、电导率温度补偿模型;最后通过对温度补偿前后灵敏度温度系数的比较来评估补偿效果,验证了传感器温度补偿效果。(4)基质含水量电导率无线检测系统应用研究。开展系统精密度、准确度和稳定性检测试验,系统试验结果分析得到:系统检测基质体积含水量的精密度为1.88%,最大误差为0.0171,相对误差小于6.72%;系统检测基质电导率的精密度为2.12%,最大误差为0.14mS/cm,相对误差小于5.26%。在系统稳定性试验的30个连续测量数据中,体积含水量值波动不超过0.0018,电导率值波动不超过0.04mS/cm,系统稳定性良好。以上应用试验结果验证了所设计的无线检测系统可以准确地检测基质含水量、电导率,并成功将结果传输到上位机进行分析处理及显示。本文通过对传感器的结构设计、无线网络系统硬件构建和软件设计,基于LabVIEW开发平台的基质含水量电导率无线检测系统应用试验研究,实现了含水量和电导率实时无线检测与监视,对基质栽培的作物生产具有一定工程应用价值。
[Abstract]:In the production of matrix cultivation, it is of great significance to master and control the parameters of water content, electrical conductivity and temperature in time. Aiming at the problem of the accuracy and stability of matrix detection system such as moisture and conductivity, based on multi-sensor fusion technology, a wireless detection system of matrix water content and conductivity is developed by using wireless network technology. It is of great value and significance to improve the automation of agricultural production and promote the progress of science and technology in the production of matrix cultivation. The main contents and results of this paper are as follows: (1) the design and Simulation of water conductivity sensor of matrix water content. Through the current detection methods of moisture conductivity analysis, determine the moisture detection by capacitance method, AC electrical current voltage four terminal method for detection of electrical conductivity; physicochemical properties of soil in different matrix, in order to ensure the sensitive element and matrix sensor is contacted, a good sensor structure is simple and easy to realize, in this paper, a unified design structure sensitive element moisture conductivity sensor; analysis of ANSYS electrostatic field simulation of sensitive element structure, determine the size of the sensitive element; water content, conductivity and temperature detection circuit optimization design, optimization and adjustment of PCB layout. (2) the construction and software design of the wireless detection system for the conductivity of the matrix water content. ZigBee wireless network technology based on the software design of sensor node and sink node, construct the matrix containing wireless detection system based on virtual instrument LabVIEW water conductivity; for the management platform, and designed computer system management procedures, the detection results of man-machine interface intuitive observation sensor nodes and curve. (3) the calibration of water conductivity sensor and the study of temperature compensation. The design of the calibration test, the temperature compensation method based on temperature characteristic parameters according to experimental data, the temperature effect on the moisture and electrical conductivity test results, using the regression analysis method to establish a model of water content, conductivity temperature compensation matrix; finally through the comparison of temperature compensation coefficient to evaluate the sensitivity before and after temperature compensation effect, verify the sensor temperature compensation effect. (4) research on the application of wireless detection system for water conductivity of matrix. To carry out the system of precision, accuracy and stability test, system test results show that the system detects the matrix volume water content precision is 1.88%, the maximum error is 0.0171, the relative error is less than 6.72%; the matrix conductivity detection system precision is 2.12%, the maximum error is 0.14mS/cm, the relative error is less than 5.26%. In the 30 continuous measurement data of the system stability test, the volume water content value fluctuates not more than 0.0018, and the conductivity value fluctuates less than 0.04mS/cm, and the system stability is good. The above application test results verify that the designed wireless detection system can accurately detect the water content and conductivity of the matrix, and successfully transfer the results to the upper computer for analysis, processing and display. Based on structure design, sensor wireless network hardware and software design of LabVIEW development platform, matrix moisture conductivity test system using wireless detection based on the moisture content and conductivity detection and real-time wireless monitoring, has a certain application value for the cultivation of the crop production base.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S126;S317

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