课题一 传感器与检测技术的基础理论.docx
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课题一 传感器与检测技术的基础理论.docx
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课题一传感器与检测技术的基础理论
课题一传感器与检测技术的基础理论
Topic1.Thebasictheoryofsensoranddetectiontechnology
1-1,thereisadigitalthermometer,itsmeasurementrangeis-50~+150,theaccuracyis0.5.Theabsoluteerrorandtherelativeerrorofindicationvaluearedeterminedwhenthevaluesare-20and+100respectively.
1-2,wanttotest240Vvoltage,requiremeasurementindicationrelativeerrorisnotgreaterthan,asktochoosemeasuringrangeis250Vvoltmeter,itsaccuracyforwhatlevel?
Ifthemeasuringrangeis300Vand500Vvoltmeter,whatistheaccuracy?
1-3itisknownthatthevoltagetobemeasuredisabout80V.Therearetwovoltagemeters,oneis0.5,themeasuringrangeis0to300V,theotheris1,andthemeasuringrangeisfrom0to100V.Whichvoltmeterisbetterformeasuring?
Why?
1-4useathreebitdigitalelectronicthermometertomeasurethetemperature.ThedigitalpanelshowsthevalueshowninFigure1-1.Theresolutionoftheinstrument,thetemperaturemeasured,therelativeerroroftheindication,andtherelativeerrorofsatisfactionaredetermined.(hint:
theupperlimitofthethreedigittableis199.9)
1-5thereisameasuringpressureinstrument,themeasuringrangeis,andtherelationshipbetweenthepressurePandtheinstrumentoutputvoltageis
Informula:
1)theoutputcharacteristicequationoftheinstrument.
2)drawaschematicdiagramofoutputcharacteristics(xaxis,Yaxisshouldbemarkedunits).
3)thesensitivityexpressionoftheinstrument.
4)drawasensitivitycurve.
5)thelinearityoftheinstrument.
1-6whatarethecomponentsofthetestsystem?
Explainthefunctionofeachpart.
1-7whataretheadvantagesofthenonelectricalmeasurementmethod?
1-8whatmeasurementmethodshouldbeadoptedwhenmeasuringtheoutputvoltageofregulatedpowersupplyvaryingwiththeload?
Howtoproceed?
1-9alineardisplacementmeasuringinstrument,whenthemeasureddisplacementchangesfrom4.5mmto5.0mm,theoutputvoltageofdisplacementmeasuringinstrumentisreducedfrom3.5Vto2.5V,andthesensitivityofthisinstrumentiscalculated.
1-10,atemperaturemeasurementsystemconsistsofthefollowingfourlinks,theirsensitivityisasfollows:
Platinumresistancetemperaturesensor:
Bridge:
Amplifier:
100(magnification)
Penrecorder:
Requirements:
(1)totalsensitivityoftemperaturemeasuringsystem;
(2)whentherecordernibis4cm.Correspondingtemperaturechangevalue.
1-11,therearethreetemperaturemeasuringinstruments,measuringrangeis0~600,accuracylevelsare2.5,2and1.5,andnowwanttomeasure500ofthetemperature,therelativeerrorofnotmorethan2.5%,whichinstrumenttochoosereasonable?
1-12whatissystemerrorandrandomerror?
Whatisthemeaningofaccuracyandprecision?
Whatkindsoferrorsdotheyreflect?
1-13whatarethecharacteristicsofrandomerrorsthatobeythenormaldistributionlaw?
1-14equalprecisionmeasuresaresistance10times,andthemeasuredvaluesareasfollows:
(1)thearithmeticmeanofthe10measurement,thestandarderrorofthestandarderrorandthearithmeticmeanofmeasurement;
(2)iftheconfidenceprobabilityis99.7%,writethetruevalueandthelimitvalueoftheresistancemeasured.
Topictworesistancetypesensor
2-1whatisthefunctionoftheelasticelementinthesensor?
2-2testthesimilaritiesanddifferencesbetweenthewireresistancestraingagesandthesemiconductorstraingauges.
2-3drawingexplainshowtouseanresistancestraingaugetomeasureanunknownforce.
2-4whatkindsofthermalresistancesensorsarethere?
Whatarethefeaturesanduses?
2-5theworkingprincipleofgassensorsandhumiditysensitiveresistancesensorsarebrieflydescribedandtheirapplicationsareillustratedbyexamples.
The2-6resistancestraingaugehasaresistancecoefficientofK=2,andisadheredtothesurfaceofacircularsteelcolumnwithadiameterof0.05malongthelongitudinaldirection,.Whenthesteelcolumnissubjectedtotheactionof10ttension,therelativechangeofthestraingaugeismeasured.Whatistherelativechangeoftheresistanceofthestraingaugewhenthestrainplatesticksalongthecircumferentialdirectionofthesteelcolumnandissubjectedtothesamepullingforce?
2-7hasaratedloadforcylindricalloadsensor2T,withoutbearing,fourstraingaugeswere,thesensitivityofthesensorforstraingauge,K=2,cylindermaterial,bridgepowersupplyvoltage,whentheloadis0.5T(alongtheaxialdirection,alongthecircumferentialdirection,paste,paste),asking:
1),2),theresistance;resistance;3)theoutputvoltageofthebridge;4)eachpieceofstraingaugepower.
2-8isameasurementofthetensionsensorcraneliftingweightisshowninfigure3-1.Andattachedtotheequalsectionaxis.ItisknownthatthesectionalareaoftheconstantsectionaxisisE,andthePoisson'sratiois0.30.Andthenominalresistancevaluesareall,andthesensitivityis2.TheyareshowninFigureB.Thebridgevoltageis2V,andtheoutputvoltageis2.6mV.O:
1)longitudinalandtransversestrainofaconstantsectionshaft.
2)howmanytonsdoesweightmhave?
2-9isastraintypecantileverforcesensor,asshowninFigure3-2.Assumingthatthethermalexpansioncoefficientofthecantileverbeamisequaltothatofthethermalexpansioncoefficientinthestraingauge,thehalfbridgedoublearmcircuitisformed.1)verify:
thesensorhastemperaturecompensationfunction;2)setthethicknessofthecantileverbeam,length,thewidthofthefixedend,themodulusofelasticityofthematerial,theinputvoltageofthebridgeroad,theoutputvoltageis1.0mV,K=2.FindtheforceF.
2-10therelationshipbetweentheresistanceofcopperresistanceandthetemperatureTcanbeexpressedinthelowerform
Whenthecopperresistanceisknown,thetemperaturecoefficientisthecopperresistancevaluewhenthetemperatureisover.
Whatisthedifferencebetween2-11DCmeasuringbridgeandACmeasuringbridge?
Whatkindofmeasuringcircuitisusedinthe2-12thermalresistancetemperaturemeasurement?
Whydoyouusethismeasuringcircuit?
Explaintheworkingprincipleofthiscircuit.
2-13usingresistanceresistanceof120,sensitivitycoefficientofK=2.0metalresistancestraingaugeandresistanceof120ohmsfixedresistorbridge,thebridgevoltageis4V,andassumethattheloadresistanceisinfinite.Whenthestrainonthestraingaugesis1and1000,thesinglearmworkbridge,thedualarmworkbridgeandtheoutputvoltageofthewholebridgearetested,andthesensitivityofthethreecasesiscompared.
2-14usesfixedresistance,resistanceofthemetalresistancestraingaugeandresistancesensitivitycoefficientK=2.0compositionofthebridge,thebridgeandthevoltageis10V,whenthestrainstrainis1000,iftheoutputvoltageisgreaterthan10mV,whichcanusethebridgemode(withoutputimpedanceisinfinite)?
2-15thefollowingfigureshowstheconstantcurrentbridge,thepowersupplyelectromotiveforceV,andtheresistancestraingaugesforthesametype.Theirresistancesareall,thesensitivitycoefficientisK=2.0.
Twostrainsheetsarerespectivelyadheredtothepositiveandnegativesidesofthesamesectionoftheequalstrengthbeam.Thestrainproducedbythebeamwithequalstrengthis5000aftertheforceisapplied,andtheoutputvoltageofthebridgeischecked.
Topicthreecapacitivesensor
Whatarethefeaturesofthe3-1capacitivesensors?
Giveanexampleofthecapacitivesensoryouknow.
3-2figure5-18showsdifferentialcylindercapacitancesensorandconversioncircuit.Verify:
whenrodHrise,
3-3,whenpurchasingandstoringgrain,thegraindepartmentneedstodeterminethedegreeofdrynessofthegrain,soastopreventmildewfromchanging.Accordingtotheknowledgeyouhavelearned,designagrainmoisturecontenttester(drawtheschematicdiagram,sensordiagram,andbrieflyexplainitsworkingprincipleandadvantagesanddisadvantages).
3-4,thesensitivityofvariableareacapacitivesensorsandvariablegapcapacitivesensorsisanalyzedInordertoimprovethesensitivityofthesensor,whatmeasurescanbetakenandwhatproblemsshouldbepaidattentionto?
3-5whyisthegaptypecapacitivesensorcharacteristicofnonlinearity?
Whatmeasurescanbetakentoimproveitsnonlinearcharacteristics?
3-6,thereisaplanarlineardisplacementdifferentialcapacitancesensor.ThemeasuringcircuitadoptsthetransformerACbridge,thestructureisasshown.Thetorchsensor,distance,dielectric,air,measuringcircuitandV.Thebridgeoutputvoltageismeasuredwhenadisplacementisinputonthemovingplate.
Themeasuringcircuitofthe3-7variablegapcapacitancesensoristheoperationalamplifiercircuit,asshown.Thestartingcapacitanceofthesensorandthedistanceofthefixedpoleplate,theoperationalamplifieristheidealamplifier(i.e.),themaximuminputvoltageisV.Whenthecapacitancesensormovesonthepolarplatetoinputadisplacement,howmuchistheoutputvoltageofthecircuit?
3-8asshowninthesquareplatecapacitor,thelengthoftheplate,thedistancebetweentheplates.Ifthedisplacementsensorisusedtomeasurethedisplacement,thesensitivityofthesensoriscalculatedandthecharacteristiccurveofthesensorisdrawn.Themediumbetweentheplatesisair,.
Topicfourinductancesensor
4-1thereareseveralcategoriesofinductivesensorsWhatarethecharacteristicsofeach?
4-2whatiscalledzeropointresidualvoltage?
What'sthecause?
4-3.Figure4-24showsabridgecircuitwithdifferentialrectification.Thecircuitconsistsofadifferentialinductancesensorandabalancedresistor(s).Onediagonalofthebridgeisconnectedwith
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