Measurement and Instrumentation／Heart Rate Measurement.docx

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1、T333JJ1SIDepartmentofE1ectrica1andE1ectronicEngineeringCurseNo.：EEE-22IICourseTit1e：MeasuremBntandInstrumentatian.ProjectName：HeartRateMeasurEment.Submittedby：MD.Mainu1HasanE-mai1：mainu1_sakinyahaD.camAbuRaihanChowdhury.SadbiAhmadSaam.E-mai1:sadbi.saammai1.cmSec：CrGroup-07Year：2drSemester：2d.GroupMe

2、mbersStudentID1.12-01-05-1072.12-01-05-1303.12-01-05-146WorkinRPrinCiPIeTheory:Thisprojectisbasedontheprincip1eofPhotop1ethysmography(PPG)whichisanon-invasivemethodofmeasuringthevariationinb1oodvo1umeintissuesusinga1ightsourceandadetector.Sincethechangeinb1oodvo1umeissynchronoustotheheartbeat,thiste

3、chniquecanbeusedtoca1cu1atetheheartrate.TransmittanceandRef1ectancearetwobasictypesofphotop1ethysmography.Forthisprojectweusedtheref1ectancePPG.ForthetransmittancePPG,a1ightsourceisemittedintothetissueanda1ightdetectorisp1acedintheoppositesideofthetissuetomeasuretheresu1tant1ight.Becauseofthe1imited

4、penetrationdepthofthe1ightthroughorgantissue,thetransmittancePPGisapp1icab1etoarestrictedbodypartzsuchasthefingerortheear1obe.However,intheref1ectancePPGzthe1ightsourceandthe1ightdetectorarebothp1acedonthesamesideofabodypart.The1ightisemittedintothetissueandtheref1ected1ightismeasuredbythedetector.A

5、sthe1ightdoesnthavetopenetratethebody,theref1ectancePPGcanbeapp1iedtoanypartsofhumanbody.Ineithercase,thedetected1ightref1ectedfromortransmittedthroughthebodypartwi11f1uctuateaccordingtothepu1satingb1oodf1owcausedbythebeatingoftheheart.ThePPGsigna1hastwocomponents,frequent1yreferredtoasACandDC.TheAC

6、componentismain1ycausedbypu1satingchangesinarteria1b1oodvo1ume,whichissynchronouswiththeheartbeat.So,theACcomponentcanbeusedasasourceofheartrateinformation.ThisACcomponentissuperimposedontoa1argeDCcomponentthatre1atestothetissuesandtotheaverageb1oodvo1ume.TheDCcomponentmustberemovedtomeasuretheACwav

7、eformwithahighsigna1-to-noiseratio.Sincetheusefu1ACsigna1ison1yaverysma11portionofthewho1esigna1,aneffectiveamp1ificationcircuitisa1sorequiredtoextractdesiredinformationfromit.CirCUitOPeration:Therearetwocircuitsusedinthisproject1)Signa1ProcessingCircuit2)1CDDisp1ayCircuit.1) Signa1ProcessingCircuit

8、:ThesensorusedinthisprojectisTCRT5000,whichisaref1ectiveoptica1sensorwithboththeinfrared1ightemitterandphototransistorp1acedsidebysideandareenc1osedinsidea1eadedpackagesothatthereisminimumeffectofsurroundingvisib1e1ight.ConnectingtheEnab1epinto5VofARDUINOwi11turntheIRemitter1EDonandactivatethesensor

9、.Afingertipp1acedoverthesensorwi11actasaref1ectoroftheincident1ight.Theamountof1ightref1ectedbackfromthefingertipismonitoredbythephototransistor.Theoutput(Vsensor)fromthesensorisaperiodicphysio1ogica1waveformattributedtosma11variationsintheref1ectedIR1ightwhichiscausedbythepu1satingtissueb1oodvo1ume

10、insidethefinger.Thewaveformis,therefore,synchronouswiththeheartbeat.Thisweaksigna1containsa1otofnoisesuperimposedontheusefu1ACsigna1whichisthenthorough1yfi1teredaseriesofsigna1processingcircuitsviaaQuadOP-AMP1M324N.Thesigna1isfirstpassedthroughaRChigh-passfi1ter(HPF)togetridoftheDCcomponent.Thecut-o

11、fffrequencyoftheHPFissetto0.7Hz.Thenextstageisanactive1ow-passfi1ter(1PF)thatismadeofanOp-Ampcircuit.Thegainandthecut-offfrequencyofthe1PFaresettoIO1and2.34Hz,respective1y.ThusthecombinationoftheHPFand1PFhe1pstoremoveunwantedDCsigna1andhighfrequencynoiseinc1uding50Hzmainsinterference,whi1eamp1ifying

12、the1owamp1itudepu1sesigna1(ACcomponent)IO1times.Theoutputfromthefirstsigna1conditioningstagegoestoasimi1arHPF/1PFcombinationforfurtherfi1teringandamp1ification.So,thetota1vo1tagegainachievedfromthetwocascadedstagesis101*101=10201.Thetwostagesoffi1teringandamp1ificationconvertstheinputPPGsigna1stonea

13、rTransistor-transistor1ogic(TT1)pu1sesandtheyaresynchronouswiththeheartbeat.AIOKpotentiometerisp1acedattheoutputofthefirstsigna1conditioningstageincasethetota1gainofthetwostagesisrequiredtobe1essthan10201.An1EDconnectedtotheoutputofthesecondstageofsigna1conditioningwi11b1inkwhenaheartbeatisdetected.

14、Thefina1stageoftheinstrumentationconstitutesasimp1enon-invertingbufferto1owertheoutputimpedance.Thisishe1pfu1ifanADCchanne1ofamicrocontro11erisusedtoreadtheamp1ifiedPPGsigna1.TheoutputisthenconnectedtoDigita1Pin8ofARDUINOUNO.Themicrocontro11ermeasuresthefrequencyofthePPGsigna1andreturnstheva1ueofhea

15、rtrateinBPM.Thefrequency(f)ofthesepu1sesisre1atedtotheheartrate(BPM)aszBeatsperminute(BPM)=60*fThefo11owingistheprogrammingcodetoca1cu1atetheHeartrate:#inc1ude/frequencymeasure1ibraryheaderfi1e#inc1ude/1CDDisp1ay1ibraryheaderfi1e1iquicICrystaI1cd(12z11,5,4,3,2);voidsetup()Seria1.begin(57600);1cd.beg

16、in(2,16);/setupthe1CDsnumberofco1umnsandrows:1cd.setCursor(0,0);/setthecursortoco1umn0,1ine1/(note:1ine1isthesecondrow,sincecountingbeginswith0):1cd.print(We1come);1cd.setCursor(0,1);/setthecursortoco1umn0,1ine21cd.print(P1aceurfinger);de1ay(10000);/A11owusertoadjustfingerforIOsandthenstartreading1cd.c1ear();/C1ears1CDScreenFreq