instructables Tsim Kev Ua Haujlwm ECG Nrog Automated Plotting ntawm Biosignal
Tsim ib lub luag haujlwm ECG Nrog Automated Plotting ntawm Biosignal
Qhov project no sib txuas txhua yam uas tau kawm rau lub semester no thiab siv rau ib txoj haujlwm. Peb txoj haujlwm yog los tsim ib lub voj voog uas muaj peev xwm siv tau los ua electrocardiogram (ECG) los ntawm kev siv cov ntsuas ntsuas amplifier, lowpass filter, thiab notch fi lter. ECG siv cov khoom siv hluav taws xob tso rau ntawm ib tus neeg los ntsuas thiab pom lub plawv ua haujlwm. Kev suav suav tau ua raws li qhov nruab nrab ntawm cov neeg laus lub siab, thiab cov thawj Circuit Court schematics tau tsim los ntawm LTSpice los txheeb xyuas qhov nce thiab txiav tawm zaus. Lub hom phiaj ntawm qhov project tsim yog raws li nram no:
- Siv cov cuab yeej cuab tam tau kawm hauv chav kuaj lub semester no
- Tsim, tsim, thiab txheeb xyuas qhov ua haujlwm ntawm lub teeb liab tau txais khoom siv
- Validate lub cuab yeej ntawm ib tug tib neeg
Cov khoom siv:
- LTSpice simulator (los yog software zoo sib xws) Breadboard
- Ntau yam resistors
- Ntau yam capacitors
- Opamps
- Cov kab hluav taws xob
- Cov lus qhia voltage qhov
- Ntaus los ntsuas cov zis voltage (ie oscilloscope)
Kauj ruam 1: Ua cov kev xam rau txhua qhov Circuit Court Cheebtsam
Cov duab saum toj no qhia txog kev suav rau txhua lub voj voog. Hauv qab no, nws piav qhia ntxiv txog cov khoom thiab cov kev suav ua tiav.
Tswv yim Ampua neej nyob
Ib qho cuab yeej amplifier, los yog IA, pab muab ntau qhov nce rau cov teeb liab qis. Nws pab nce qhov loj ntawm lub teeb liab kom nws pom ntau dua thiab cov waveform tuaj yeem txheeb xyuas.
Rau kev suav, peb xaiv ob qhov kev ntsuas qhov sib txawv rau R1 thiab R2, uas yog 5 kΩ thiab 10 kΩ, feem. Peb kuj xav kom qhov nce mus rau 1000 yog li lub teeb liab yuav yooj yim rau kev txheeb xyuas. Qhov piv rau R3 thiab R4 yog tom qab ntawd daws los ntawm qhov sib npaug hauv qab no:
Vout / (Vin1 – Vin2) = [1 + (2*R2/R1)] * (R4/R3) –> R4/R3 = 1000 / [1 + 2 * (10) / (5)] –> R4/ R3 = 200
Peb mam li siv qhov piv txwv no los txiav txim siab seb txhua tus nqi resistor yuav yog dab tsi. Cov nqi yog raws li nram no:
R3 = 1 kΩ
Tsis Ntse Lim
Ib lub thais lim attenuates signals nyob rau hauv ib tug nqaim band ntawm frequencies los yog tshem tawm ib zaus. Qhov zaus peb xav tshem tawm hauv qhov no yog 60 Hz vim tias feem ntau cov suab nrov uas tsim los ntawm cov khoom siv hluav taws xob yog nyob ntawm qhov zaus. AQ yam yog qhov piv ntawm qhov nruab nrab zaus rau bandwidth, thiab nws kuj pab piav qhia cov duab ntawm qhov loj me. Q qhov loj dua ua rau qhov nqaim nres. Rau kev suav, peb yuav siv Q tus nqi ntawm 8.
Peb txiav txim siab xaiv cov nqi capacitor peb muaj. Yog li, C1 = C2 = 0.1 uF, thiab C2 = 0.2 uF.
Qhov sib npaug peb yuav siv los xam R1, R2, thiab R3 yog raws li nram no:
R1 = 1 / (4 * pi * Q * f * C1) = 1 / (4 * pi * 8 * 60 * 0.1E-6) = 1.6 kΩ
R2 = (2 * Q) / (2 * pi * f * C1) = (2 * 8) / (2 * pi * 60 * 0.1E-6) = 424 kΩ
R3 = (R1 * R2) / (R1 + R2) = (1.6 * 424) / (1.6 + 424) = 1.6 kΩ
Lowpass Lim
Ib lub lim dej uas tsis tshua muaj attenuates siab frequencies thaum tso cai qis zaus dhau los. Qhov kev txiav tawm zaus yuav muaj nqi ntawm 150 Hz vim qhov ntawd yog qhov tseeb ECG tus nqi rau cov neeg laus. Tsis tas li ntawd, qhov nce (K tus nqi) yuav yog 1, thiab qhov tsis tu ncua a thiab b yog 1.414214 thiab 1, feem.
Peb xaiv C1 kom sib npaug 68 nF vim tias peb muaj lub capacitor. Rau nd C2 peb siv cov kab zauv hauv qab no:
C2 >= (C2*4*b) / [a^2 + 4*b(K-1)] = (68E-9*4*1) / [1.414214^2 + 4*1(1-1)] -> C2 > = 1.36E-7
Yog li ntawd, peb xaiv C2 kom sib npaug 0.15 uF
Txhawm rau xam cov nqi ntawm ob qhov resistor, peb yuav tsum siv cov kab zauv hauv qab no:
R1 = 2 / (2*pi*f*[a*C2 + sqrt([a^2 + 4*b(K-1)]*C2^2 – 4*b*C1*C2)] = 7.7 kΩ
R2 = 1 / (b*C1*C2*R1*(2*pi*f)^2) = 14.4 kΩ
Kauj ruam 2: Tsim Schematics ntawm LTSpice
Tag nrho peb cov khoom tau tsim thiab khiav ib tus zuj zus ntawm LTSpice nrog AC cheb tsom xam. Cov nqi siv yog cov uas peb suav hauv kauj ruam 1.
Kauj ruam 3: Tsim Instrumental Ampli -ib
Peb tsim cov cuab yeej amplifier ntawm lub breadboard los ntawm kev ua raws li schematic ntawm LTSpice. Thaum nws tau tsim, lub tswv yim (daj) thiab tso zis (ntsuab) voltages tau nthuav tawm. Cov kab ntsuab tsuas muaj qhov nce ntawm 743.5X piv rau kab daj.
Kauj ruam 4: Tsim lub Notch Filter
Tom ntej no, peb tsim lub thais lim rau ntawm lub breadboard raws li lub schematic ua ntawm LTSpice. Nws tau tsim nyob ib sab ntawm IA Circuit Court. Peb mam li sau cov tswv yim thiab tso zis voltage tus nqi ntawm ntau zaus los txiav txim qhov loj. Ces, peb graphed magnitude vs. zaus ntawm cov zajlus kom muab piv rau LTSpice simulation. Qhov tsuas yog qhov peb hloov pauv yog qhov tseem ceeb ntawm C3 thiab R2 uas yog 0.22 uF thiab 430 kΩ, raws li. Ib zaug ntxiv, qhov zaus nws tshem tawm yog 60 Hz.
Kauj ruam 5: Tsim lub Lowpass Filter
Peb mam li tsim cov lim dej qis rau ntawm lub khob cij raws li qhov schematic ntawm LTSpice ib sab ntawm qhov ntsuas qhov ntsuas. Peb mam li sau cov tswv yim thiab tso zis voltages ntawm ntau zaus los txiav txim qhov loj. Tom qab ntawd, peb npaj qhov loj thiab zaus los sib piv rau LTSpice simulation. Tib tus nqi peb hloov pauv rau qhov lim no yog C2 uas yog 0.15 uF. Qhov kev txiav tawm zaus peb tau txheeb xyuas yog 150 Hz.
Kauj ruam 6: Test on Human Subject
Ua ntej, txuas peb tus kheej cov khoom ntawm lub voj voog ua ke. Tom qab ntawd, sim nws nrog simulated lub plawv dhia kom paub tseeb tias txhua yam ua haujlwm. Tom qab ntawd, tso cov electrodes ntawm tus neeg kom qhov zoo nyob ntawm lub dab teg sab xis, qhov tsis zoo yog nyob rau sab laug pob taws, thiab hauv av yog nyob rau sab xis pob taws. Thaum tus neeg tau npaj lawm, txuas lub roj teeb 9V rau lub hwj chim opamps thiab tso saib cov teeb liab tso zis. Nco ntsoov tias tus neeg yuav tsum nyob twj ywm rau li 10 vib nas this kom tau txais kev nyeem ntawv tseeb.
Zoo siab, koj tau ua tiav ib qho kev siv ECG!
Cov ntaub ntawv / Cov ntaub ntawv
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