Non destructive testing of fabric weight in the
weaving process
Y.-S. Gloy, T. Gries and G. Spies
13th International Symposium on
Nondestructive Characterization of
Materials
Content
 Institut für Textiltechnik der RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Content
 Institut für Textiltechnik der RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
RWTH Aachen University





36.000
Students in 126 courses of study
340
Institutes with 480 professorships
6900
Employees (thereof 65% scientists)
750 Mio € Total budget, thereof:
320 Mio € Third party funding
Source: RWTH Aachen University,
Photos Peter Winandy
4
RWTH Aachen Campus
ITA
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between industry and
university:
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till 2020
Source: rha reicher haase + associierte
5
technology and
competence fields
mobility
building &
living
health
application fields
Comprehensive textile
process chains
semi-finished textiles &
products
raw materials:
natural fibers, polymers,...
The unique position of ITA
energy
6
Institut für Textiltechnik der RWTH Aachen
University
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 85 Scientists
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 50 Students majoring in textile
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7
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Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Woven fabrics
 Woven fabrics
 Rectangular crossing of warp and weft
 Applications
 Clothing
 Technical textiles e.g.
 Airbags, Parachutes, Composites
Airbag; Source: ITA
3D-Fabric; Source: ITA
 Weaving machines
 Standard machine speed up to 1000 rpm
 Weft insertion efficiency of 2000 m/min
 150.000 machines produced worldwide (2011)
 Fabric weight important quality criteria
Weaving Maschine; Source: Picanol nv, Ieper, Belgium
9
Principle of a weaving machine
Shed
Warp stop motion
Back rest
Weft
Warp
Reed
Fabric takeoff
Fabric
Direction of production
Warp beam
Fabric beam
Principle of a weaving machine; Source: ITA
10
Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Capacitive sensor
U(C)
 Capacity of a parallel plate capacitor is
determined by
ε
C=C(ε)
 Where C = capacity; ε0 = 8.854 x 10-12,
εr = dielectric relative constant, S = area and d = distance
Principle of a capacitive sensor
 According to Carvalho et al. a relationship is established between the capacity and a
Electrodes
passing yarn mass
Measurement slot
Capacitive sensor ; Source: ITA
12
Installation of capacitive sensor
Instalation of capacitive sensor on a weaving machine; Source: ITA
13
Validation of capacitive sensor
Capacitive sensor signal [V]
3,80
3,30
2,80
17 picks per cm
8 picks per cm
2,30
1,80
6
8
10
12
14
16
18
Picks per cm
14
Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
X-ray sensor
 Radiometric absorption according to Beer-Lambert law
with

where I = Intensity of the beam, I0 = original intensity of the beam, L = length of beam into the substance, e =
Euler's number, about 2.718, µ = the attenuation coefficient ρ = the density, µ/ρ = the mass attenuation
coefficient and ρ•L = the area density, m = total mass of the object and A = total area
 Sensor from BST ProControl Rengsdorf GmbH,
Rengsdorf, Germany
 Radiometric absorption system
 Accelerating voltage < 5kV, can be used
in Germany without approval
 Measurements between 50 and 1000 g/m²
 Resolution of 0,1 g/m²
Principle of an X-Ray sensor, Source: ITA
16
Installation of X-ray sensor
Installation of x-ray sensor on a weaving machine; Source: ITA
17
Comparison – X-Ray sensor vs. fabric weight
(DIN EN 12127)
 Weaving machine running at 400 rpm
-2,35
400
-2,4
380
-2,45
370
-2,5
360
-2,55
350
340
-2,6
DIN EN 12127
330
X-ray sensor
-2,65
320
X-ray sensor signal [V]
Fabric weight [g/m2]
390
-2,7
310
-2,75
300
10
12
14
16
18
20
Picks per cm
18
Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Closed-loop control
 Due to dead time (depending on rpm and weft density) use of Smith Predictor
 PI Controller and prediction of plant without dead time
 Integration into loom via components form iba AG, Fürth, Germany components
FW = Fabric weight
GF = transfer element of signal to fabric weight
GR = transfer element of PI Controller
GS = transfer element of sensor
GW = transfer element of weaving machine
GT = transfer element of dead time
~
G i = transfer element of model of the plant
Smith Predictor control of fabric weight; Source: ITA
20
Step response
Sensor voltage US [V]
 Step in weft density
21
Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Validation of Smith Predictor
 Field trial within WeyermannTechnical Textiles GmbH & Co. KG, Wegberg, Germany
 Accuracy of fabric control less 3 %
 System accepted by weaving mill workers
Weft density
voltage Us [V]
DWeft [1/cm]
ΔFWSensor
/ ΔFW desired
2.7
2.66
2.66
2.64
2.64
2.62
2.62
Sensor signal
2.6
Conventional
controller
2.56
0
50
100
150
2.56
2.54
200
250
300
22
20
actuating variable
18
16
14
12
0
50
100
150
Time t [s]
200
250
0
50
100
150
200
250
300
200
250
300
22
Actuating
actuatingvariable
variable
20
18
16
14
12
10
10
Sensor signal
2.6
2.58
2.58
2.54
Measurement
2.7
2.68
Smith Predictor
2.68
Weft density
DWeft [1/cm] Sensor voltage Us [V]
Simulation
0
50
100
150
300
Time t [s]
23
Content
 Institut für Textiltechnik of RWTH Aachen University
 Testing of fabric weight in the
weaving process
 Introduction
 Capacitive sensor
 X-ray sensor
 Closed-loop control
 Validation
 Summary and outlook
Summary and outlook
 Summary
 Capacitive sensor not suitable
 X-Ray sensor can be used to monitor fabric weight
 Smith predictor as control loop for field test
vy
vx
z
54 x 45 mm²
y
x
 Outlook
 Integration of further sensor
 Camera system to detect weft errors and
weft density developed at ITA
 Transfer to further textile processes
25
Thank you for your attention
The authors would like to thank the German Research Foundation DFG for their
support of the depicted research within the Cluster of Excellence "Integrative
Production Technology for High-Wage Countries“
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