基于LabVIEW的液位测控系统设计

本科毕业设计论文I摘要液位计算机测量与控制实验系统是为西北工业大学航空学院民航工程系综合实验平台而开发的课程教学实验系统。液位测量与控制系统集传感器信号的采集、调理、转换、检测和控制为一体，是实时交互式图形界面应用系统。该系统采集液位信号并用计算机可视化界面实时显示液位高度的变化过程；通过交互式对话框设置期望的液位高度，在检测当前液位的基础上控制进/出水阀门，从而对实际液位高度进行控制。论文介绍了液位计算机测量与控制系统的结构与功能；分析了硬件系统中测量与控制电路的组成及工作原理；计算了信号调理电路中测量放大器的增益及各元件参数；使用PROTEL软件绘制了信号调理电路图；介绍了多功能数据采集卡NIUSB-6008的特点、功能及软件开发平台LabVIEW；分析了系统的软件程序；介绍了液位计算机测控系统的用户使用界面所能实现的功能。针对实验系统对液位进行开关控制所带来的问题，提出了用PID控制方法进行改进的措施。关键词：液位测控，压力传感器，信号调理，NIUSB-6008，LabVIEW本科毕业设计论文IIABSTRACTTheliquidlevelmeasurementandcontrolcomputerexperimentalsystemisacourseteachingexperimentalsystemwhichisusedtodevelopthecomprehensiveexperimentalplatformforAviationInstituteofCivilEngineeringofNWPU.Theliquidlevelmeasurementandcontrolsystemwithreal-timeinteractivegraphicalinterfaceisofthesensorsignalacquisition,conditioning,conversion,testingandcontrolfunctions.Thesystemacquiresthesignalsofliquidlevelandcomputerinterfacereal-timetoshowtheliquidlevelchangingprocess.Throughaninteractivedialogbox,thedesiredwaterlevelisset.Theactualwaterleveliscontrolledbasedonthecurrentliquidleveldetectionthroughtheimport/outletvalves.Thestructureandfunctionoftheliquidlevelmeasurementandcontrolcomputerexperimentalsystemisintroducedatfirst.Thehardwaresystemcompositionandworkingprincipleisanalyzed,andthegainandeachcomponentsparametersofmeasuringamplifierinsignalconditioningcircuitarecalculated.ThesignalconditioningcircuitisdrawnwithPROTEL,andthefeaturesandfunctionsofthemulti-functiondataacquisitioncardNIUSB-6008andsoftwaredevelopmentplatformLabVIEWareintroduced.Thesystemsoftwareprogramisalsoanalyzed.Forthecontrolproblemsofimport/outletvalvesoftheliquidlevelmeasurementandcontrolcomputerexperimentalsystem,aPIDcontrolmethodisproposedtoimprovethesystemperformances.KEYWORDS：liquidlevelmeasurementandcontrol，pressuresensor，signalconditioning，NIUSB-6008，LabVIEW本科毕业设计论文III目录摘要.................................................................................................................................IABSTRACT.....................................................................................................................II第一章绪论..................................................................................................................11.1课题背景................................................................................错误!未定义书签。1.2系统组成................................................................................错误!未定义书签。1.3系统工作原理........................................................................................................21.4本文的主要内容....................................................................................................2第二章传感器及信号调理..............................................................................................32.1数据采集................................................................................................................32.1.1数据采集技术.................................................................................................32.1.2数据的采样.....................................................................................................32.2传感器....................................................................................................................42.2.1传感器的选用.................................................................................................42.2.2压阻式压力传感器的基本原理.....................................................................52.2.3传感器存在的问题及其解决方法..................................................................52.3信号调理电路........................................................................................................72.3.1第一级数据放大器..........................................................................................72.3.2第二级放大器..................................................................................................82.4整体电路................................................................................................................8第三章液位控制回路....................................................................................................113.1基本组件及原理特性...........................................................................................113.1.1六反向器（74LS04）...................................................................................113.1.2电磁阀...........................................................................................................123.2继电器...................................................................................................................133.2.1固态继电器SSR...........................................................................................14本科毕业设计论文IV3.2.2交流型SSR的工作原理..............................................................................143.2.3SSR的注意事项............................................................................................16第四章计算机液位测控系统........................................................................................194.1多功能数据采集卡...................................................................................