by: john den engelse date: 19 – 6 - 2013
DESCRIPTION
Master Thesis at SKF: Lateral force estimation acting at a vehicle wheel using a hub bearing unit equipped with strain gauges and Eddy-current sensors. By: John den Engelse Date: 19 – 6 - 2013. Presentation overview. Introduction Research goals Strain gauge measurements - PowerPoint PPT PresentationTRANSCRIPT
1Challenge the future
Master Thesis at SKF:Lateral force estimation acting at a vehicle wheel using a hub bearing unit equipped with strain gauges and Eddy-current sensorsBy: John den EngelseDate: 19 – 6 - 2013
2Challenge the future
Presentation overview• Introduction
• Research goals
• Strain gauge measurements
• Eddy-current sensor measurements
• Field- / validation measurements
• BETSY calibration method
• Conclusions
3Challenge the future
Introduction1
4Challenge the future
Introduction: Load Sensing Bearing (LSB)
• Why would we like to measure forces?
• Monitoring the mechanical loads of a bearing.
• Control the active safety systems in vehicles like the ABS (longitudinal force) and ESC (lateral force).
• Measure the vertical load in, for instance, trucks.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
5Challenge the future
Introduction: Load Sensing Bearing (LSB)
• How? A load sensing hub bearing unit instrumented with:
• 6 strain gauges: deformation of the bearing outer ring.
• 2 Eddy-current sensors: tilting movement of the ABS-ring.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
6Challenge the future
Research goals2
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Research goals1) Lateral force estimation, acting at a vehicle wheel,
using strain gauges and Eddy-current sensors.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
2) Calibration of the load sensing bearing using the Bearing Test System (BETSY)
8Challenge the future
Strain gauge measurements3
9Challenge the future
Strain gauge measurements
• The strain gauges measure the deformation of the bearing outer ring at six places along the circumference.
• The deformation provides information about the loads acting on the bearing.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
10Challenge the future
Strain gauge measurements
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
• So what happens?
WarningThe following slide features a mathematical
trickperformed by a professional
and under the supervision of a professional.Accordingly, the TU Delft and the students
must insist that no one attempt torecreate of re-enact any trick oractivity performed on this slide.
12Challenge the future
Strain gauge measurements: MLRA
The entries of F have dimensions [1 x ] with N the number of samplesThe entries of have dimensions [1 x (6 1)] with the order the polynomialThe entries of have dimensions [(6 1) x N] with t
Nn n
n n
he order the polynomial
2
1
...
y
z
Fy
Fz
n
F
F
1( )T TF
• Multivariate Linear Regression Analysis (MLRA): The output is assumed to be a linear combination of the input and higher order terms of the input.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
20 1 0 ... n
y nF
• For one single dimension:
• For multi input multi output
13Challenge the future
1) Absolute value problem2) Difference in sensitivity for Fy < 0 N and Fy > 0 N
3) Difference in response for 0 Hz < f < 1 Hz and 1 Hz < f < 10 Hz
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
Strain gauge measurements: MLRA
14Challenge the future
Strain gauge measurements: Fy estimation block diagram
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
15Challenge the future
Eddy-current sensormeasurements
4
16Challenge the future
Eddy-current sensor measurement
• Why (inductive) Eddy-current sensor measurements?
• The strain gauges are subject to the absolute value problem.
• Strain measurements are subject to low frequent thermal influences.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
17Challenge the future
• ABS-ring integrated in the seal of the bearing. 48 holes and
48 spokes.
• The tilting movement of the ABS-ring gives an estimate of the
lateral force Fy acting on the bearing.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
Eddy-current sensor measurement
18Challenge the future
• Two Eddy-current sensors are mounted into the knuckle.
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
Eddy-current sensor measurement
19Challenge the future
Eddy-current sensor measurement: Signal
• The change in the lower values provides the information
about Fy
35 35.005 35.01 35.015 35.02 35.0250
1
2
3
4
5
6
7
8Eddy-current sensor signals BETSY: BMW+0005
Time [s]
Sig
nal [
V]
Bottom sensorTop sensor
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
20Challenge the future
Eddy-current measurement: Low value algorithm
• Algorithm to retrieve these lower values.• Based signal derivative • Maximum change per time sample ∆ymax • An initial condition y0 (the equilibrium value)• The wheel speed
35 35.005 35.01 35.015 35.02 35.0250
2
4
6
8
Time [s]S
enso
r sig
nal [
V]
Eddy-current sensor - low value algorithm
Algorithm inputUnfiltered algorithm output
35 35.005 35.01 35.015 35.02 35.0250
2
4
6
8
Time [s]
Sen
sor s
igna
l [V
]
Eddy-current sensor - low value algorithm
Algorithm inputFiltered algorithm output
Discontinious output
Continuous output
Introduction – Research goals – Strain gauge measurements – Eddy-current sensors measurements – Field- / validation measurements - …
21Challenge the future
Field measurements5
22Challenge the future
Field measurements
• The LSB equipment has been built in a BMW E60 and tests have been performed at the test track at SKF
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
23Challenge the future
Field measurements
• Movie: Circle run at 30 km/h
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
24Challenge the future
Field measurements
• A Kistler VELOS force measuring wheel is used as reference
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
25Challenge the future
Field measurements: Tilt vs Fy
• Eddy-current sensor measurement.
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 1, RMS error = 261.2115
Tilt [m]
Fy [N
]
Total track 3 Total track 4 Total track 5 left 20 kmph left 30 kmph right 20 kmph right 30 kmph left 10, 20 and 30 kmph right 10, 20 and 30 kmph
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 2, RMS error = 260.8957
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 3, RMS error = 192.1875
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 4, RMS error = 186.6831
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 5, RMS error = 171.4631
Tilt [m]
Fy [N
]
Tilt versus lateral force approximated by nth order polynomials
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 6, RMS error = 161.7996
Tilt [m]
Fy [N
]
N
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 1, RMS error = 261.2115
Tilt [m]
Fy [N
]
Total track 3 Total track 4 Total track 5 left 20 kmph left 30 kmph right 20 kmph right 30 kmph left 10, 20 and 30 kmph right 10, 20 and 30 kmph
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 2, RMS error = 260.8957
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 3, RMS error = 192.1875
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 4, RMS error = 186.6831
Tilt [m]
Fy [N
]
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 5, RMS error = 171.4631
Tilt [m]
Fy [N
]
Tilt versus lateral force approximated by nth order polynomials
-100 -50 0 50 100
-3000
-2000
-1000
0
1000
2000
Order fit = 6, RMS error = 161.7996
Tilt [m]
Fy [N
]
N
• Data is approximated by a 2nd and a 6th order polynomial:
Accuracy vs extrapolation characteristics
26Challenge the future
Field measurements
• Strain measurement
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Lateral force [N]
Stra
in [
m/m
]
Fy vs straingauge 1
Test 1Test 2Test 3Test 4
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Fy vs straingauge 2
Lateral force [N]
Stra
in [
m/m
]
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Fy vs straingauge 3
Lateral force [N]
Stra
in [
m/m
]
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Fy vs straingauge 4
Lateral force [N]
Stra
in [
m/m
]
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Fy vs straingauge 5
Lateral force [N]
Stra
in [
m/m
]
-4000 -3000 -2000 -1000 0 1000 2000 3000
0
100
200
300
400
Fy vs straingauge 6
Lateral force [N]
Stra
in [
m/m
]
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
27Challenge the future
Field measurements : Fy estimation
• Two force estimation algorithms. Both for an in-situ calibration and a BETSY calibration.
1) Using 4 MLRA on the strain gauges and use the Eddy-current sensors for the determination of the direction.
2) Using both the Eddy-current sensors and the strain gauges for the force estimation.
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
28Challenge the future
Field measurements : Algorithm 1
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
• Using 4 MLRA on the strain gauges and use the Eddy-current
sensors for the determination of the direction.
29Challenge the future
Field measurements: Algorithm 2
• Using both the Eddy-current sensors and the strain gauges
for the force estimation
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
30Challenge the future
Field measurements : Fy estimation, result
• Estimated force vs time for both algorithms.
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
0 10 20 30 40 50 60-3000
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000Lateral force estimation: In-situ calibration
Time [s]
Fy [N
]
Measured forceEstimated force by 2 LMRAs and tiltEstimated force by four LMRAs
31Challenge the future
Field measurements : Fy estimation, result
• Estimated force vs measured force for both algorithms.
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000-3000
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000Lateral force estimation: in situ calibration
Measured force [N]
Est
imat
ed fo
rce
[N]
Estimated force by 2 LMRAs and tiltEstimated force by four LMRAsIdeal
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
32Challenge the future
Field measurements : Fy estimation, result
• Estimation errors
Frequency content Method RMS Error [N] Error [%]
0 Hz - 1 Hz
MLRA 188,82 16,46Tilt 2nd order 229,84 20,04Tilt 6th order 174,47 15,21
In-situ calibration
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
Frequency content Method RMS Error [N] Error [%]1 Hz - 10 Hz MLRA 130,89 141,82
Frequency content Method RMS Error [N] Error [%]0 Hz - 10 Hz Algorithm 1 232,00 20,090 Hz - 10 Hz Algorithm 2 216,82 18,78
33Challenge the future
BETSY calibration6
34Challenge the future
Strain gauge measurements: BETSY
• What is BETSY and why do we want to use it?
• The Bearing Test System is a 5 Degree of Freedom (DoF)
system, where forces and moments are applied in 5 DoF by hydraulic actuators.
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
35Challenge the future
BETSY calibration: strain
εBETSY = c3 ∙ Fy + c4εvehicle = c1 ∙ Fy + c2
4 2,
3 1
- -BETSY vehicley test
c cF
c c
3 3 24
1
-vehicleBETSY A vehicle B
c c c c c cc
• •
•
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 1
Fy [N]
Stra
in [ m
/m]
Papenburg BETSY
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 2
Fy [N]
Stra
in [
m/m
]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 3
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 4
Fy [N]
Stra
in [
m/m
]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 5
Fy [N]
Stra
in [ m
/m]
Papenburg and BETSY: Lateral force Fy versus strain
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 6
Fy [N]
Stra
in [
m/m
]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 1
Fy [N]
Stra
in [ m
/m]
Papenburg BETSY
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 2
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 3
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 4
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 5
Fy [N]
Stra
in [ m
/m]
Papenburg and BETSY: Lateral force Fy versus strain
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 6
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 1
Lateral force [N]
Stra
in [ m
/m]
Left cornering Right cornering Linear fitlines
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 2
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 3
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 4
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 5
Lateral force [N]
Stra
in [ m
/m]
Papenburg: Lateral force Fy versus strain including linear fits
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 6
Lateral force [N]S
train
[ m/m
]
36Challenge the future
BETSY calibration: Eddy-current sensors
-100 -80 -60 -40 -20 0 20 40 60 80 100-4000
-3000
-2000
-1000
0
1000
2000
Tilt [m]
Fy [N
]
Tilt versus Fy for BETSY and field measurements at SKF: 2nd order
BETSYField measurements SKF
Good!
37Challenge the future
Field measurements : Fy estimation, result
• Estimated Fy vs time for both algorithms
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
0 10 20 30 40 50 60-3500
-3000
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000Lateral force estimation: In-situ calibration
Time [s]
Fy [N
]
Estimated force by four LMRAsEstimated force by 2 LMRAs and tiltMeasured force
38Challenge the future
Field measurements : Fy estimation, result
• Estimated Fy vs measured Fy for both algorithms.
-3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000-3000
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000Lateral force estimation: in situ calibration
Measured force [N]
Est
imat
ed fo
rce
[N]
Estimated force by four LMRAsEstimated force by 2 LMRAs and tiltIdeal
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
39Challenge the future
Field measurements : Fy estimation, result
• Estimation errors using a BETSY calibration
• So we can use BETSY for calibration?
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
Frequency content Method RMS Error [N] Error [%]0 Hz - 10 Hz Algorithm 1 335,29 29,040 Hz - 10 Hz Algorithm 2 374,55 32,44
Frequency content Method RMS Error [N] Error [%]
0 Hz - 1 Hz
MLRA 191,44 16,69Tilt 2nd order 261,23 22,78Tilt 6th order 342,64 29,88
Frequency content Method RMS Error [N] Error [%]1 Hz - 10 Hz MLRA 265,34 287,49
40Challenge the future
Reproducibility: strain
• Reproducibility is necessary for calibration of a whole
production line of LSB
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
Test run 1 Test run 2 Test run 3 Linear fitlines
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 2
Lateral force [N]
Stra
in [
m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 3
Lateral force [N]
Stra
in [
m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 4
Lateral force [N]
Stra
in [
m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 5
Lateral force [N]
Stra
in [
m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 6
Lateral force [N]
Stra
in [
m
/m]
BETSY: Reproducibility
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 1
Lateral force [N]
Stra
in [
m
/m]
Not good!
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
Lateral force [N]
Stra
in [ m
/m]
Fy vs straingauge 1
Papenburg SKF Linear fitlines
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600Fy vs straingauge 2
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600Fy vs straingauge 3
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600Fy vs straingauge 4
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600Fy vs straingauge 5
Lateral force [N]
Stra
in [ m
/m]
Fy vs strain for the field measurements performed at SKF and Papenburg
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600Fy vs straingauge 6
Lateral force [N]
Stra
in [ m
/m]
41Challenge the future
Reproducibility: Eddy-current sensors
• Reproducibility is necessary for calibration of a whole
production line of LSB
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
Good!
-150 -100 -50 0 50 100 150 200 250-8000
-6000
-4000
-2000
0
2000
4000
Tilt [m]
Fy [N
]
Tilt versus Fy for BETSY
BETSY NEWBETSY OLD
20112012
42Challenge the future
Conclusions7
43Challenge the future
Conclusions: lateral force estimation
• In the semi-static frequency range the strain gauges as well as the
Eddy-current sensors can be used for force estimation with errors ranging from 15 % - 20 %.
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
• In the dynamic frequency range the lateral force is not correlated with
the strain and ABS-ring deflection.• Regarding the Eddy-current sensors BETSY can be used for
calibration.• Regarding the strain gauges sensors BETSY cannot be
used for calibration.
44Challenge the future
Questions?
Thank you for your attention !
45Challenge the future
Backup slides
46Challenge the future
Introduction: Load Sensing Bearing
• What forces act on a vehicle?
• 3 forces:• Fx = longitudinal force • Fy = lateral force• Fz = vertical force
• 3 moments:• Mx = moment around the x-axis• My = moment around the y-axis• Mz = moment around the z-axis
47Challenge the future
Strain gauge measurements: Applied loads
• Cycle consisting of 24 load steps.• Load steps with 10 seconds of duration.
• Between each load step a 10 seconds interval of running without load is inserted.
• Combinations of static and dynamic forces are applied.
0 100 200 300 400 500 600 700-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1x 10
4
Time [s]
Forc
e [N
], M
omen
t [N
m]
Betsy: 24 load cases with superpositioned noise
Fy [N]Fz [N]Mx [Nm]
48Challenge the future
Strain gauge measurements: Signal conditioning process
• Filtering• Static offset and drift• Inverted signal strain gauge 3• No-load intervals• Scaling to physical dimensions
0 1 2 3 4 5 6 7 8 9 10
x 104
0
50
100
150
200
250
300
350
400Conditioned strain signals
Time [samples]
Stra
in [
m/m
]
Strain 1Strain 2Strain 3Strain 4Strain 5Strain 5
0 100 200 300 400 500 600-1
-0.5
0
0.5
1
1.5
2Unconditioned strain signals
Time [s]
Stra
in s
igna
l [V
]
Strain 1Strain 2Strain 3Strain 4Strain 5Strain 5
49Challenge the future
BETSY calibration• BETSY-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 1
Lateral force [N]
Stra
in [m
/m]
Left cornering Right cornering Linear fitlines
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 2
Lateral force [N]
Stra
in [m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 3
Lateral force [N]
Stra
in [ m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 4
Lateral force [N]
Stra
in [ m
/m]
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 5
Lateral force [N]
Stra
in [m
/m]
BETSY: Lateral force Fy versus strain including linear fits
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
0
100
200
300
400
Fy vs straingauge 6
Lateral force [N]
Stra
in [m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 1
Lateral force [N]
Stra
in [ m
/m]
Left cornering Right cornering Linear fitlines
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 2
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 3
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 4
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 5
Lateral force [N]
Stra
in [ m
/m]
Papenburg: Lateral force Fy versus strain including linear fits
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 6
Lateral force [N]
Stra
in [ m
/m]-8000 -6000 -4000 -2000 0 2000
-200
0
200
400
600Fy vs straingauge 1
Fy [N]
Stra
in [ m
/m]
Papenburg BETSY
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 2
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 3
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 4
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 5
Fy [N]
Stra
in [ m
/m]
Papenburg and BETSY: Lateral force Fy versus strain
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 6
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 1
Fy [N]
Stra
in [ m
/m]
Papenburg BETSY
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 2
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 3
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 4
Fy [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 5
Fy [N]
Stra
in [ m
/m]
Papenburg and BETSY: Lateral force Fy versus strain
-8000 -6000 -4000 -2000 0 2000-200
0
200
400
600Fy vs straingauge 6
Fy [N]
Stra
in [ m
/m]
• Some differences are present
• How can we compensate for those differences.
• Field
• BETSY and field
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
50Challenge the future
BETSY calibration
By describing both sides of the V-shape by a 1st order polynomial two coefficients, Ca and Cb, can be derived for both positive and negative Fy to transform te one to the other. (So 4 coefficients in total).
Εleft,BETSY = c1,left ∙ Fy,left + c2,leftεright,BETSY = c1,right ∙ Fy,right + c2,right
Εleft,field = c3,left ∙ Fy,left + c4,leftεright,Field = c3,right ∙ Fy,right + c4,right
BETSYField
, 2 , 4,
1 3
- -right BETSY right fieldy right
c cF
c c
1 4 1 1 42 2 , ,
3 3
- -vehicle vehicleBETSY A right vehicle B right
c c c c cc c c cc c
51Challenge the future
BETSY calibration
• By describing both sides of the V-shape by a 1st order polynomial two coefficients, Ca and Cb, can be derived for both positive and negative Fy to transform te one to the other. (So 4 coefficients in total).
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 1
Lateral force [N]
Stra
in [ m
/m]
Left cornering Right cornering Linear fitlines
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 2
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 3
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 4
Lateral force [N]
Stra
in [ m
/m]
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 5
Lateral force [N]
Stra
in [ m
/m]
Papenburg: Lateral force Fy versus strain including linear fits
-8000 -6000 -4000 -2000 0 2000 4000-200
0
200
400
600
800Fy vs straingauge 6
Lateral force [N]
Stra
in [ m
/m]
εleft = c1,left ∙ Fy,left + c2,left
εright = c1,right ∙ Fy,right + c2,right
2 4,
1 3
- -BETSY vehicley test
c cF
c c
1 4 1 1 42 2 , ,
3 3
- -vehicle vehicleBETSY A right vehicle B right
c c c c cc c c cc c
52Challenge the future
BETSY calibration: Eddy-current sensors
-100 -80 -60 -40 -20 0 20 40 60 80 100-4000
-3000
-2000
-1000
0
1000
2000
Tilt [m]
Fy [N
]
Tilt versus Fy for BETSY and field measurements at SKF: 6th order
BETSYField measurements SKF
53Challenge the future
Estimation errors distributions
-2000 -1500 -1000 -500 0 500 10000
0.005
0.01
0.015
0.02
0.025
0.03Probability density distribution error: 2 LMRAs and tilt
Pro
babi
lity
Error [N]-2000 -1500 -1000 -500 0 500 1000
0
0.005
0.01
0.015
0.02
0.025
0.03Probability density distribution error: 4 LMRAs
Pro
babi
lity
Error [N]-2000 -1500 -1000 -500 0 500 1000
0
0.005
0.01
0.015
0.02
0.025
0.03Probability density distribution error: 2 LMRAs and tilt
Pro
babi
lity
Error [N]-2000 -1500 -1000 -500 0 500 1000
0
0.005
0.01
0.015
0.02
0.025
0.03Probability density distribution error: 4 LMRAs
Pro
babi
lity
Error [N]
54Challenge the future
Summary: lateral force estimation
…– Eddy-current sensors measurements – Field- / validation measurements – BETSY calibration method - Conclusions
0 Hz – 1 HzCalibration Strain Tilt 2nd order fit Tilt 6th order fitIn-situ 16.5 % 20.0 % 15.2 %BETSY 16.7 %* 22.8 % 29.9 %
• Fy estimation summary:
55Challenge the future
Recommendations
• Errors obtained with estimation using the Eddy-current sensor are mainly caused by the rubber seal and low value algorithm.
• This research focused on Fy. Next: Fx, Fz
• Online testing
• Excite with higher amount of dynamic forces
56Challenge the future
Questions?
Thank you for your attention !
57Challenge the future
Questions?
Thank you for your attention !