iziyalezo Dizayina I-ECG Esebenzayo Ngokuhlelwa Kwesakhiwo Okuzenzakalelayo Kwe-Biosignal
Dala i-ECG eSebenzayo Ngokuhlela Okuzenzakalelayo kwe-Biosignal
Le phrojekthi ihlanganisa konke okufundiwe kule semester futhi ikusebenzise kumsebenzi owodwa. Umsebenzi wethu ukwakha isekethe ekwazi ukusetshenziswa njenge-electrocardiogram (ECG) ngokusebenzisa izinsimbi. ampi-lifier, isihlungi se-lowpass, nesihlungi se-notch. I-ECG isebenzisa ama-electrode abekwe kumuntu ukuze alinganise futhi abonise umsebenzi wenhliziyo. Izibalo zenziwe ngokususelwe kunhliziyo yomuntu omdala emaphakathi, futhi i-schematics yesekethe yasekuqaleni yadalwa ku-LTSpice ukuze kuqinisekiswe inzuzo nokunqamuka kwamafrikhwensi. Izinhloso zalo msebenzi wokuklama zimi kanje:
- Sebenzisa amakhono ezinsimbi afundwe elebhu kule semester
- Dizayina, yakha, futhi uqinisekise ukusebenza kwedivayisi yokutholwa kwesignali
- Qinisekisa idivayisi ngesihloko somuntu
Izinsiza:
- I-LTSpice simulator (noma isofthiwe efanayo) Ibhodi lesinkwa
- Ama-resistors ahlukahlukene
- Ama-capacitor ahlukahlukene
- Opamps
- Izintambo ze-Electrode
- Okokufaka ivoltagumthombo
- Idivayisi yokulinganisa umthamo wokukhiphayotage (oscilloscope)
Isinyathelo 1: Yenza Izibalo zengxenye ngayinye yesekethe
Izithombe ezingenhla zibonisa izibalo zesekethe ngayinye. Ngezansi, ichaza kabanzi mayelana nezingxenye kanye nezibalo ezenziwe.
Izinsimbi Ampokokuphila
I-instrumentation ampi-lifier, noma i-IA, isiza ukuhlinzeka ngenani elikhulu lenzuzo yezimpawu ezisezingeni eliphansi. Isiza ukukhulisa usayizi wesiginali ukuze ibonakale kakhudlwana futhi i-waveform ingahlaziywa.
Ezibalweni, sikhethe amanani amabili aphikisayo angahleliwe e-R1 ne-R2, angu-5 kΩ no-10 kΩ, ngokulandelanayo. Sifuna futhi inzuzo ibe ngu-1000 ukuze isignali ibe lula ukuyihlaziya. Isilinganiso sika-R3 no-R4 sibe sesixazululwa ngezibalo ezilandelayo:
I-Vout / (Vin1 – Vin2) = [1 + (2*R2/R1)] * (R4/R3) –> R4/R3 = 1000 / [1 + 2*(10) / (5)] –> R4/ R3 = 200
Sibe sesisebenzisa leso silinganiso ukuze sinqume ukuthi inani ngalinye le-resistor lizoba yini. Amanani ami kanje:
R3 = 1 kΩ
Isihlungi se-Notch
Isihlungi se-notch sinciphisa amasignali ngaphakathi kwebhande elincane lamafrikhwensi noma sisusa ifrikhwensi eyodwa. Imvamisa esifuna ukuyisusa kulesi simo ngu-60 Hz ngoba umsindo omningi okhiqizwa izinto zikagesi ukuleyo frikhwensi. I-AQ factor isilinganiso semvamisa yesikhungo kumkhawulokudonsa, futhi isiza ukuchaza ukuma kwesakhiwo sobukhulu. Isici esikhulu se-Q siphumela kubhendi yokumisa ewumngcingo. Ezibalweni, sizobe sisebenzisa inani elingu-Q elingu-8.
Sinqume ukukhetha amanani e-capacitor ebesinawo. Ngakho, C1 = C2 = 0.1 uF, futhi C2 = 0.2 uF.
Izibalo esizozisebenzisa ukubala u-R1, u-R2, no-R3 zimi kanje:
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
Isihlungi se-Lowpass
Isihlungi sokudlula okuphansi sinciphisa amaza aphezulu kuyilapho sivumela amaza aphansi ukuthi adlule. I-cutoff frequency izoba nenani elingu-150 Hz ngoba lelo inani elilungile le-ECG kubantu abadala. Futhi, inzuzo (inani lika-K) izoba ngu-1, futhi ama-constants a no-b angu-1.414214 kanye no-1, ngokulandelanayo.
Sikhethe i-C1 ukuthi ilingane no-68 nF ngoba sinaleyo capacitor. Ukuze C2 sisebenzise isibalo esilandelayo:
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
Ngakho-ke, sikhethe i-C2 ukuthi ilingane no-0.15 uF
Ukuze sibale amanani amabili aphikisayo, bekufanele sisebenzise zibalo ezilandelayo:
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
Isinyathelo 2: Dala ama-Schematics ku-LTSpice
Zontathu izingxenye zakhiwe futhi zasebenza ngazodwana ku-LTSpice ngokuhlaziywa kokushanela kwe-AC. Amanani asetshenzisiwe yilawo esiwabale esinyathelweni 1.
Isinyathelo 3: Yakha Instrumentation Ampli- er
Sakha i-instrumentation amplifier ebhodini lezinkwa ngokulandela uhlelo oluku-LTSpice. Uma selakhiwe, okokufaka (okuphuzi) nokuphumayo (okuluhlaza) voltages zaboniswa. Ulayini oluhlaza unenzuzo engu-743.5X kuphela uma kuqhathaniswa nolayini ophuzi.
Isinyathelo 4: Yakha Isihlungi Se-Notch
Okulandelayo, sakhe isihlungi se-notch ebhodini lezinkwa ngokususelwa kuhlelo olwenziwe ku-LTSpice. Yakhiwe eduze kwesekethe ye-IA. Sabe sesiqopha ivolumu yokufaka nokuphumayotagu-e ubeka amanani kumafrikhwensi ahlukahlukene ukuze anqume ubukhulu. Bese, senze igrafu ubukhulu ngokuqhathaniswa nemvamisa kusakhiwo ukuze siqhathanise nokulingiswa kwe-LTSpice. Okuwukuphela kwento esiyishintshile amanani e-C3 ne-R2 angu-0.22 uF no-430 kΩ, ngokulandelana. Futhi, imvamisa eyisusayo ngu-60 Hz.
Isinyathelo 5: Yakha Isihlungi se-Lowpass
Sibe sesakha isihlungi sokudlula okuphansi ebhodini lokunamathisela esekelwe kuhlelo lwe-LTSpice eduze kwesihlungi se-notch. Sibe sesiqopha ivolumu yokufaka nokuphumayotagkumafrikhwensi ahlukahlukene ukuze kutholwe ubukhulu. Bese, sakha ubukhulu nemvamisa ukuze siyiqhathanise ne-LTSpice simulation. Okuwukuphela kwevelu esilishintshile kulesi sihlungi bekuyi-C2 engu-0.15 uF. Imvamisa yokunqamuka ebesiyiqinisekisa ngu-150 Hz.
Isinyathelo 6: Isivivinyo Ngesihloko Somuntu
Okokuqala, xhuma izingxenye ezintathu zesekethe ndawonye. Bese, ihlole ngokushaya kwenhliziyo okufanisiwe ukuze uqinisekise ukuthi yonke into iyasebenza. Bese, beka ama-electrode kumuntu ukuze i-positive ibe sesihlakaleni sokudla, i-negative iseqakaleni lesobunxele, futhi umhlabathi useqakaleni langakwesokudla. Uma umuntu eselungile, xhuma ibhethri elingu-9V ukuze unike amandla i-opamps bese uveza isignali yokuphumayo. Qaphela ukuthi umuntu kufanele ahlale ethule cishe imizuzwana eyi-10 ukuze afunde okunembile.
Halala, udale ngempumelelo i-ECG ezenzakalelayo!
Amadokhumenti / Izinsiza
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iziyalezo Dizayina I-ECG Esebenzayo Ngokuhlelwa Kwesakhiwo Okuzenzakalelayo Kwe-Biosignal [pdf] Iziyalezo Dala i-ECG eSebenzayo Ngokuhlela Okuzenzakalelayo kwe-Biosignal, Dizayina i-ECG esebenzayo, i-ECG esebenzayo, ukuhlelwa kwe-Biosignal |
