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1 ECT-ERT hardware and sensor dr. Darius Styra 22 months visit in TomoKIS Computer engineering department Technical University of Lodz
1
ECT-ERT hardware
and sensordr. Darius Styra
22 months visit in TomoKIS
Computer engineering department
Technical University of Lodz
2
Content
1. Improvement of AC-Based tomography hardware;
2. Dual modality ECT-ERT sensor;
3. Compact size ECT hardware;
4. Rotatable field tomography;
5. Tomogram quality estimation;
6. Conclusions;
7. Dissemination of experimental results.
3
Basics of ECT: system
4
Basics of ECT: sensor
I I
I I
Cx= 1 fF÷1 pF CA≅CB= ~200 pF CA / Cx= ~2(102÷105)
A
A
C CB
BCx
3D ECT sensor
Equivalent circuit
5
Basics of ECT: hardware
Sex1
ELECTRODE
OUTCsw
Rf
Cf
3
2
6
+
-
Out
Sm1
Uex
Csw
Block diagram of ECT system
Picture of ECT hardware
Input circuit with switches
6
1. Improvement of ECT hardware
ECT hardware with 32 channels was designed by
Yangbo He in DENIDIA, there is still to improve:
• Hardware connection to sensor;
• Flexible sensitivity of input circuit;
• Algorithm for flexible calibration of hardware;
•USB & Ethernet interfaces.
7
1.1 Hardware connection to sensor
Sex1
ELECTRODE
OUTCsw
Rf
Cf
3
2
6
+
-
Out
Sm1
Uex
CswRf
Sm1
OUT
Uex
Sm3
Sm2
3
2
6
+
-
Out
Sex3Sex1
Sex2
ELECTRODE
Cf
Before: simple switch Improved: T-switch
Additional switches for electrode
connection to measurement circuit
prevent hardware from signal
saturation, which is accompanied by
a significant drop of the hardware
temperature and therefore
minimization of power dissipation.
Signal decreased 1820 times at
500kHz.
8
1.2 Flexible sensitivity of input
circuit
3
2
6
+
-
Out
CswIN
Rf 1
Rf 2
Sf 1
Cf
OUT
Sf 1
Csw
OUT
Cf
CswRf 2
3
2
6
+
-
Out
Rf 1
IN
Sf 2
Csw
Sf 3
Before: simple switch Improved: T-switch
Flexible sensitivity for ECT ��ERT
switching.
Switchable frequency range
increased up to 14MHz.
9
1.3 Algorithm for flexible calibration
of hardware
High permittivity calibration
(DC PGA calculation)
Low permittivity calibration
(Offset calculation)
Calibration
End
High permittivity calibration
(DC PGA calculation)
Low permittivity calibration
(Offset calculation)
High permittivity calibration
(AC PGA calculation)
Calibration
End
Before: simple switch Improved: AC gainsSet DCPGA = 1;
Set Offset = 0;
Set ACPGA =1
Start
Fill sensor with high
permittivity mixture
Calculate AC gain
End
Read ADC
AC gains calibration
10
1.5 Ethernet and USB interfacesPowerful DAQ: USB & Ethernet
• Prevented from signal saturation and high temperature;
• Suitable for ECT and ERT measurements;
• Suitable for any kind of 2D or 3D sensor;
•USB & Ethernet hardware for rapid data transfer.
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2 Dual modality ECT-ERT sensor
Two systems:
• Oil and emulsion up to 40% of salt water: high resistivity, ECT
mode;
• Salt water and emulsion up to 50% of oil: low resistivity, ERT
mode.
Or one system:
• Dual modality ECT-ERT electrodes;
• Switchable ECT-ERT hardware.
12
2.1 Dual modality ECT/ERT sensor
Insulated electrode with naked pin
13
2.2 Dual modality ECT/ERT sensor
• The same electrodes for ERT and ECT;
• The same wires for ERT and ECT;
• The same hardware for ERT and ECT.
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 200 400 600 800 1000 1200f, kHz
U, mVDM ERT ERT TW PIN ERT ERT TW
DM ECT ECT HP SHLD ECT ECT HP
14
3. Compact ECT hardware
Previous systems:
• Big hardware, built in 19” Euro case;
• A Lot of components;
• High power consumptions;
• Stray immune capacitance
measurement circuits.
15
• Compact size;
• Low power;
• Availability of supplied by battery
wireless hardware;
• New stray capacitance compensation.
3.1 Hardware: a) pictures
16
3.1 Hardware: b) block diagram
PS021 from ACAM.de
• measurement rate: up to
50 kHz;
• resolution: up to 6 aF;
• range: 0fF ÷ 10nF;
• current: down to 10µA;
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1 2
1212 CC m =
3.2 Theory of stray capacitance
compensation
18
1 2
2313
23131212
CC
CCCC m +
+=
3
3.2 Theory of stray capacitance
compensation
19
C12m C12
C13 C23⋅
CAA
+
C24
C23 C34⋅
CAA
+
C14
C13 C34⋅
CAA
+
⋅
C23 C34⋅ C13 C34⋅+ C34 C35⋅+
CAA
C14+ C45+ C24+
+ +
C25
C23 C35⋅
CAA
+
C24
C23 C34⋅
CAA
+
C45
C34 C35⋅
CAA
+
⋅
C23 C34⋅ C13 C34⋅+ C34 C35⋅+
CAA
C14+ C45+ C24+
+
C15
C13 C35⋅
CAA
+
C14
C13 C34⋅
CAA
+
C45
C34 C35⋅
CAA
+
⋅
C23 C34⋅ C13 C34⋅+ C34 C35⋅+
CAA
C14+ C45+ C24+
+
⋅
C25 C15+C23 C35⋅ C13 C35⋅+
CAA
+
C23 C34⋅ C13 C34⋅+
CAA
C14+ C24+
C45
C34 C35⋅
CAA
+
⋅
C23 C34⋅ C13 C34⋅+ C34 C35⋅+
CAA
C14+ C45+ C24+
+
+
CAA C 13 C 23+ C 34+ C 35+
3.2 Theory of stray capacitance
compensation: a) equation solving method
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C12m C12C13C23⋅
C13 C23++
C24C14⋅
C24 C14++
C25C15⋅
C25 C15++:=
3.2 Theory of stray capacitance
compensation: b) neglecting method
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• Cm.i – capacitance between i and all other short-circuited;
• Cm.j – capacitance between j and all other short-circuited;
• Cm.i,j – capacitance between connected i with j and all other short-circuited.
3.2 Theory of stray capacitance
compensation: c) short-circuiting method
∑≠
=)(
,.
ik
kiim CC
∑≠
=)(
,.
jk
kjjm CC
∑∑≠≠
+=),(
,
),(
,,.
jik
kj
jik
kijim CCC
2
,...
,
jimjmim
ji
CCCC
−+=
22
3.2 Theory of stray capacitance
compensation: d) application for ECT sensor
143211413121. scswswswwm CCCCCCCCC +++++++=
243122423122. scswswswwm CCCCCCCCC +++++++=
2143212423141312. scscswswwwm CCCCCCCCCCC +++++++++=
+
–
=
2
2 43211212
swswswsw CCCCCC
++++=
2
,...
,
swjimjmim
ji
CCCCC
Σ−−+=
23
3.2 Theory of stray capacitance
compensation: e) measurement speed
12
)1(+
−+=
NNNM2/)1( −= NNM
Stray capacitance immune Stray capacitance compensated
1.0671.1421.1971.2441.3211.467Difference D
52913779563722Stray compensated M
49612066452815Stray immune M
3216121086Electrode number N
Single measurement number
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3.3 Experimental resultsa) comparison of methods
0.00%0.00%0.0000.0002.0702.2745. Isolated
15.1%12.71%0.3120.2892.3822.5634. Without compensation
0.10%0.70%0.002-0.0162.0722.2583. Short-circuiting
7.25%8.58%-0.15-0.1951.9202.0792. Neglecting
1.16%0.66%-0.024-0.0152.0462.2591. Equation solving
C45, %C12, %C45, pFC12, pF
Relative errorErrorC45, pFC12, pFMethod
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3.4 Experimental resultsb) stray capacitance compensation for ECT
sensor
0.7600.23831.315Stray compensated1 – 72*, full1.590.494
1.0160.43330.821Stray immune1 – 7 2*, full
0.0140.3132249.867Stray compensated1 – 22*, full0.020.353
0.0250.5662249.514Stray immune1 – 22*, full
2.2680.0934.101Stray compensated1 – 71*, empty-1.38-0.057
4.0690.1694.158Stray immune1 – 7 1*, empty
0.0730.311424.062Stray compensated1 – 21*, empty0.000.004
0.1330.562424.058Stray immune1 – 21*, empty
diff*, %diff*, fFU*, %U*, fFC, fFMethodElectrodeSensor
U* - uncertainty type A, p=95%; diff* - difference between measurement results;
1* - sensor with 160mm diameter, electrode length 160mm and 25mm electrode width;
2* - sensor with 45mm diameter, electrode length 100mm and 9.5mm electrode width.
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U1(t)
I1(t)
I3(t)
U3(t)U2(t)
I2(t)
0 60 120 180 240 300 36010
5
0
5
1010
10−
U 1 φ( )
U 2 φ( )
U 3 φ( )
3600 φ
deg
3 phase voltage
U1 φ( ) Um cos φ 0deg+( )⋅:= U2 φ( ) Um cos φ 120deg+( )⋅:= U3 φ( ) Um cos φ 240deg+( )⋅:=
4. Rotatable Field Tomography
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4.1 Rotatable Field Tomography
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4.2 HardWare for RFT
R4R
+
-
U10AD844
3
26
74
18
5
+Vs
C1C
+Vs
R3R
+Vs
-Vsin
-Vs
+
-
U8AD844
3
26
74
18
5
R2
Rvar
+Vs
-Iout
+
-
U5AD844
3
26
74
18
5
+
-
U7AD844
3
26
74
18
5
-Vs
+
-
U2AD844
3
26
74
18
5
+Vs
+Vs
+
-
U3AD844
3
26
74
18
5
-Vs
-VsC2C
-Vs
-Vs
+Iout
-Vs
R6R
+
-
U4AD844
3
26
74
18
5
+Vs
R1R
-Vs -Vs
R5R
+Vsin
+Vs+Vs
+
-
U9AD844
3
26
74
18
5
+Vs
+
-
U1OPA602
3
26
7 14 5
+
-
U6OPA602
3
26
7 14 5
-Vs
Block diagram of electronics
DDS BUF ADCAMP
DAQ
Ele1
DDS BUF ADCAMP
Ele2
DDS BUF ADCAMP
Ele3
Current excitation Voltage measurement
Schematics for current excitation
•No need of switches
•High quality tomogram
•High speed tomography
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4.3 Rotatable Field Tomography
• Only average value;
• There is need of further research.
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5. Tomogram quality estimationSigma L2 normalized error is the root mean square of the components of the error
M, N – number of point;
x – exact value of point;
xTOM – value of reconstructed point.
( )
( )%100
1 1
,
1 1
,,
x
N
n
M
m
x
nm
x
N
n
M
m
x
nmTOMnm
Lx
x
xx
∑∑
∑∑
= =
= =
−=δ
Cross - correlation is the root mean square of the components of the error
R1
N M⋅0
N 1−
n 0
M 1−
m
xn m,
yn m,
⋅( )∑=
∑=
⋅M, N – number of point;
x – exact value of point;
y – value of reconstructed point.
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5. Tomogram quality estimationSftware for comparison tomogram done by IAESTE student Danijiel Petanovic
Software is able:
• evaluate Sigma Lx erros between two2D tomograms;
• evaluate correlation between two 2D
tomograms;
• enteramanuallt 2D tomogram;
• Draw tomograms
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6. ConclusionsImprovement of AC-based ECT hardware• Prevented from signal saturation;
• Suitable for ECT and ERT measurements;
• Suitable for any kind of 2D or 3D;
• Reduced noise;
• USB & Ethernet hardware for rapid data transfer.
Dual modality ECT-ERT sensor
• The same electrodes for ERT and ECT;
• The same wires for ERT and ECT;
• The same hardware for ERT and ECT.
Compact ECT hardware
• New concept of ECT hardware
• New stray capacitance compensation method;
• Compact size;
• Low price;
• Availability of supplied by battery and/or wireless hardware.
Rotatable Field Tomography:
• No success, only average value.
Error estimation in tomograms
• Two tomograms comparison using signa L norms;
• Two tomograms comparison using correlation;
• Manual entering of tomogram
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7. Dissemination of research results
Presentations:• 6thWorld Congress on Industrial Process tomography in Beijing;
• Electrical Engineering and Electronics 2010 in Kowno;
• Marie Curie Conference ESOF 2010 in Torino;
• Lecture in Technical University of Warszawa 2009.
Papers:• Improvement of AC-based ECT Hardware;
• Stray Capacitance Compensation for Non Stray-Immune ECT Systems;
• Application of Multi Modality Tomography for Multi Phase Flow Measurements;
• Application of ECT/ERT/gamma ray image reconstruction for Multi Phase Flow Measurements;
• Improvement of ECT Hardware.
Few opinions:• The papers are very good. Thanks for sending them to me.
• I read your two papers carefully. My opinion is that the paper on improvement of ECT hardware is very good, but the compact ECT paper is less impressive.
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Acknowledgements
• The author would like to thank prof. Erling A. Hammer from University of Bergen for valuable help.
• The work is funded by the European Community‘s Sixth Framework Program – Marie Curie Transfer of Knowledge Action (DENIDIA, contract No.: MTKD-CT-2006-039546)
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Thanks for your attention
