생체계측 II Report #7 2005200427 송성진
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Medical Instrumentation II
description
생체계측 II Report #7 2005200427 송성진. Multi physics. ref. V o l t a g e C u r r e n t C h a r g e. P r e s s u r e F l o w V o l u m e. ρ is density L is length η is viscosity C is compliance. ρ is resistivity. Catheter Model. - PowerPoint PPT Presentation
Transcript of 생체계측 II Report #7 2005200427 송성진
Medical Instrumentation II
Multi physics.
Medical Instrumentation II
<Electric Circuit>
V o l t a g eC u r r e n tC h a r g e
<Fluid Mechanics>
P r e s s u r eF l o w
V o l u m e
][AL
IVR
dtdIVL/
dtdVIC/
]/[ 34 msParL
FPR
2/ rL
dtdFPL
ulussYoungC mod.'
ref. ρ is resistivity
ρ is densityL is lengthη is viscosityC is compliance
Catheter Model.
Medical Instrumentation II
Diaphragm
Strain gage
Cable
Pi -> Vi
Po -> Vo
Blood vessel
+
-
We must measure
pressure, Pi !
Sensor
Equivalent Circuit Model.
Medical Instrumentation II
occi vdtdiLiRv
dtdvCi o
d
1)
2)
Medical Instrumentation II
io
dco
dco vdtvdCL
dtdvCRv 2
2
3) Second order Ordinary Differential Equation(ODE)
4) Laplace equivalent transform
)()(]12[ 2
2
tKvtvwD
wD
ionn
1K
c
dc
LCR
2
max1 wCL
wdc
n
Medical Instrumentation II
Damping Ratio
Natural Frequency(or undamped Frequency)
Frequency transfer function
Medical Instrumentation II
12)(
1)()()(
2
nn
i
o
wj
wjjV
jVjH
nn wj
w 2)(1
12
Medical Instrumentation II
2
1
2222 )(1
2tan
)(4])(1[
1
n
n
nnw
w
ww
n
n
nnw
www
2tan)(4])(1[
1 1
2222
Medical Instrumentation II
ІHІ
Wn
1/2ζ
ω
∞ → 0
We know that Wn is 1/root(LcCd)
almost 80Hz ~ 90Hz
1. If ζ = 0.5 ,
Medical Instrumentation II
ІHІ
Wn ω
Flat (response)
Critical dampingBut, Wn is increasing, not flatSo ІHІ is decreasing
1/2ζ = 1
2. If ζ = 1 ,
Medical Instrumentation II
ІHІ
Wn ω
Over dampedIt is that high frequency decreasing
1/2ζ = 0.5
1
Ex)
Medical Instrumentation II
Іvi(ј ω)І
30Hz ω
If Іvi(ј ω)І
Wn is going to be more 30Hz
so that amplified same magnitude.
3. If ζ = 0.25 ,
Ex)
Medical Instrumentation II
ІHІ
Wn ω
Under damped
1/2ζ = 2 1
Phaser transfer graph
Medical Instrumentation II
<H
-π/2
-π
→ ∞
ω
Wn
ζ increasing -> G -> B -> R
We must regulate phase & magnitude response
appropriate
Question) Why change D by jω?
Medical Instrumentation II
iooo vvdtdvRC
dtvdLC 2
2
iooo vvRCDvvLCD 2
io vvRCDLCD )1( 2
11)( 2
RCDLCDv
vDHi
o
General RLC Circuit
d/dt Δ= D (operater)
Operational transfer function
1. D operation
Medical Instrumentation II
2. Fourier transform
iooo vvvjRCvjLC )()( 2
jDi
o DHjRCjLCV
VjH
)(1)()(
1)( 2
dttdvfdte
dttdv tj )()(
)()()()()( jetvedttdvetv
dttdv tjtjtj
Medical Instrumentation II
dtetvjetvdtddte
dttdv tjtjtj
)()()(
dtetvjetvd tjtj
)()(0
)()( jVjdtetvj tj
)()( tvfjdttdvf
