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생체계측 II Report #3 2005200427 송성진

생체계측 II Report #3 2005200427 송성진. Resistive Sensor. Strain gage : changes in L & ρ Force sensing resistor : changes in A Thermistor : changes in L Potentiometer : changes in L. FSR(Force sensing resistor). F. Thermistor. A & F is proportion.

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생체계측 II Report #3 2005200427 송성진

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  1. 생체계측 II Report #32005200427 송성진 Medical Instrumentation II

  2. Resistive Sensor • Strain gage : changes in L & ρ • Force sensing resistor : changes in A • Thermistor : changes in L • Potentiometer : changes in L Medical Instrumentation II

  3. FSR(Force sensing resistor) F Thermistor A & F is proportion. R & 1/F is inverse proportion. R R R R∞ F T NTC (Negative Temperature Coefficient) Medical Instrumentation II

  4. Design. (A) V0 vs F or T : Non - linear (B) Medical Instrumentation II

  5. (C) Bridge circuit S3 S4 in = 0 Va Vb E[v] IA R1 S2 ip = 0 reference Rs (D) Linearigation Rp Linear Range R Medical Instrumentation II

  6. Capacitive Sensor A x Most capacitor sensor are based on changes in x Medical Instrumentation II

  7. Inductive Sensor • Self Inductance • Mutual Inductance • Differential Inductance (1) Self Inductance (2) Mutual Inductance F a + x Vs Vo - b Medical Instrumentation II

  8. (3) LVDT (Linear Variable Differential Transformer) D a δ c (a) When core is at X = 0 Vo Vs d X = 0 f - δ b Vo = 0 e - D Vcd is Blue, Vef is Red and Vo is Black (c) When core is at X = + δ (b) When core is at X = + δ Medical Instrumentation II

  9. Problem 13. • Using LVDT, A object that is a reciprocasting motion verticality direction measure location. This is y(t), changing by next page figure. 1st coil’s voltage is V(t) = sin(2π x 1000t) [v]. • (a) Design the LVDT output signal in 0 ~ 10ms. 2nd coil’s phase isn’t delay, Suppose LVDT is linear in ± 20mm. • (b) Write verticality direction y(t) by LVDT output signal. • (c) Write calibration method for output voltage represent [mm] unit Medical Instrumentation II

  10. Problem 13. LVDT F y(t) 180 ̊ Phase change 20mm X=20mm t -20mm X=0 5ms 10ms 40mm X=-20mm Medical Instrumentation II

  11. Method 1. Rectifier + LPF No Phase change! LPF V(t) FWR Vo(t) V(t) t Medical Instrumentation II

  12. Method 2. Phase-sensitive demodulation sin(2πx10³t) LPF X Vo(t) V(t) g X g IVo(t)I t Medical Instrumentation II

  13. Matlab 3. • 5~10ms 사이에 0.01ms 씩 샘플링하여 그래프 표현 filter함수 배열 사용. Medical Instrumentation II

  14. Piezoelectric sensor x (1) x(t) Vo(t) Medical Instrumentation II

  15. (2) I H I fc = 1 / 2πRC T Medical Instrumentation II

  16. If you plan to use the piezoelectric sensor for measuring pulse the lowest frequency of pulse. Signal is assumed to be 0.1Hz. Medical Instrumentation II

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