Virtual Testing and Subjective Evaluation of Chassis ... · •Driving Simulator process for...
Transcript of Virtual Testing and Subjective Evaluation of Chassis ... · •Driving Simulator process for...
IVK – Institut für Verbrennungsmotoren und
Kraftfahrwesen
Virtual Testing and Subjective Evaluation of
Chassis Components in theStuttgart Driving Simulator
IPG Apply & Innovate, Karlsruhe
September 20 – 21, 2016
Dipl.-Ing. Minh-Tri Nguyen
I. Motivation and Purpose
II. Principle of Driving Dynamics Evaluation in the Simulator
III. Implementation of the Driving Scenario
IV. Human’s Perception of Vehicle Motion
V. Evaluation of Chassis Components
VI. Summary
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Overview
Motivation and Purpose
I.
• Integration of the driving simulator in the process of chassis development
and driving dynamics
Vision: Holistic approach for vehicle development
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Motivation and Purpose
Stuttgart
Driving
Simulator
Vehicle
Aeroacoustics
Wind Tunnel
IVK Driving
Dynamics
Test Bench
• Improving system understanding in early stages of the development
process by subjective evaluation
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Motivation and Purpose
Definition,
Concept Simulation
Prototype Building,
ValidationTuning,
Optimization
SOPSubjective
Evaluation
Objective
Data
TestingSimulation
• Approach for driving dynamics evaluation in the driving simulator
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Motivation and Purpose
Use Case,
Benefits,
Limits.
Customized
Modeling
and
Simulation
- Subjective
driving
impression
- Comparison to
Reality
Principle of Driving Dynamics Evaluation in the Simulator
II.
• Common process for subjective and objective evaluation of driving
dynamics
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Principle of Driving Dynamics Evaluation in the Simulator
δ
ψ, ϑ, φ, …
Driver’s r
ea
ctio
n
Ve
hic
le’s
rea
ctio
n
Disturbances
Driver
Vehicle
Subj. Evaluation
Obj. Data
Correlation subj.- obj.
?
• Driving Simulator process for subjective evaluation of driving dynamics
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Principle of Driving Dynamics Evaluation in the Simulator
δ
Ψ‘, ϑ‘, φ‘
Disturbances
Driver
SimulatorModel Motion Cueing
On/Off
Ψmod, ϑmod, φmodModel’s reaction
Driver’s r
ea
ctio
n
Sim
ula
tor’s
rea
ctio
n
Subj. Evaluation
Correlation subj.- obj.
Implementation of the Driving Scenario
III.
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Requirements for the Vehicle Model
Implementation of the Driving Scenario
Co
mp
uti
ng
Tim
e
Subjective improvement
due to model complexity
Limit of
Real Time
Capability
Accuracy of Modeling
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IPG CarMaker Vehicle Model for Driving Dynamics Evaluation
Implementation of the Driving Scenario
Parameterized
MF 5.2
Suspension Elements
Kin./ Elakin. (.skc)
Pfeffer Steering
0,0
0,2
0,4
0,6
-15,0 -5,0 5,0 15,0
Aerodynamic Coeff.
5-Mass Model
With Rigid Body
-30 -20 -10 0 10 20 30-1000
-500
0
500
1000
1500
2000Force-distance-graph damper
Da
mp
er
forc
e [
N]
Displacement x0 [mm]-1.5 -1 -0.5 0 0.5 1 1.5
-1000
-500
0
500
1000
1500
2000Force-velocity-graph damper
Da
mp
er
forc
e [
N]
Velocity v0 [m/s]-30 -20 -10 0 10 20 30
-1000
-500
0
500
1000
1500
2000Force-distance-graph damper
Da
mp
er
forc
e [
N]
Displacement x0 [mm]-1.5 -1 -0.5 0 0.5 1 1.5
-1000
-500
0
500
1000
1500
2000Force-velocity-graph damper
Da
mp
er
forc
e [
N]
Velocity v0 [m/s]
Enhanced Damper-
Topmount-Model
• Scenario
Driving on Autobahn with road impact,
e.g. bumps, bridge joints and road unevenness
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Transferring On-Road Scenario to Virtual Reality
Implementation of the Driving Scenario
Focus on:
Exact reproduction of
vehicle’s body motion
Subjective driving impression
comparable to reality
Autobahn Test Run
VR in the Simulator
Superposition of synthetic road spectrum and impulses on vehicle body
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Structure of Excitation
Implementation of the Driving Scenario
10-2
100
102
104
10-20
10-10
100
Frequency [Hz]
He
ave
(f)
[m
²/H
z]
Heave Motion CG
Synthetic Road Spectrum
Excitation
Measured
Vehicle’s Motion
after Vertical
Impact
𝐹𝑥𝐹𝑦𝐹𝑧CG
Forces and
Moments
Referred to CG
𝑎𝑥𝑎𝑦
𝑎𝑧 𝜑
𝜗 𝜙
𝑀𝑥
𝑀𝑦
𝑀𝑧
0 1000 2000 3000 4000 5000-0.1
-0.05
0
0.05
0.1
Length [m]
He
ave
[m
]
Human’s Perception of Vehicle Motion
IV.
Using defined excitation to generate criteria of perception:
• General statements about the “Threshold of Perception” regarding to the
Autobahn scenario
• Evaluating the “Just Noticeable Difference” due to impulses
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“Threshold of Perception” and the “Just Noticeable Difference”
Human’s Perception of Vehicle Motion
DriverVirtual Vehicle Model
Excitation
Threshold of Perception
Noticeable Difference
• Experimental measuring of detected impulses
• Correlation between the intensity of impulses and the stochastic road
excitation
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Driver’s Task to Evaluate the Threshold of Perception (ToP)
Human’s Perception of Vehicle Motion
ToP
200 205 210 215 220 225 230-5
-4
-3
-2
-1
0
1
2
3
4
5Body's Reaction Due to Excitation
Time [s]
Vert
ical A
cc. [m
/s²]
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.650
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
RMS of Vertical Excitation [m/s²]
Am
plitu
de Im
pu
lse [
m/s
²]
Correlation - Impulse - Excitation
Bo
dy A
cc.
in m
/s²
Time in s
RMS Vertical Road Excitation
AM
P I
mp
uls
e
Correlation AMP / RMS
𝑎𝐼𝑚𝑝 = 𝒑 ∗ 𝑎𝑟𝑜𝑎𝑑 + 𝒒
Linear correlation between impulse amplitudes and RMS of vehicle’s
vertical acceleration due to road disturbances.
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Results of the ToP
Human’s Perception of Vehicle Motion
0 0.2 0.4 0.6 0.8 10
1
2
3
4
5
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f V
ert
ical im
pacts
in
m/s
²
Threshold of Perception
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f L
on
git
ud
inal im
pacts
in
m/s
² Threshold of Perception
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2
2.5
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f R
ollin
g im
pacts
in
rad
/s²
Threshold of Perception
0 0.2 0.4 0.6 0.8 10
1
2
3
4
5
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f V
ert
ical im
pacts
in
m/s
²
Threshold of Perception
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f L
on
git
ud
inal im
pacts
in
m/s
² Threshold of Perception
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2
2.5
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f R
ollin
g im
pacts
in
rad
/s²
Threshold of Perception
0 0.2 0.4 0.6 0.8 10
1
2
3
4
5
RMS of vehicle`s vertical acc. due to road disturbance in m/s²
Am
plitu
de o
f V
ert
ical im
pacts
in
m/s
²
Threshold of Perception
● detected
● non-detectedSeparation of
Vehicle Motion
• Experimental measuring of three impulses in a row (3AFC-Method)
• Probability of detecting a difference between two impulses
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Driver’s Task to Evaluate the Just Noticeable Difference (JND)
Human’s Perception of Vehicle Motion
JND
0 0.5 1 1.5 2 2.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
540 541 542 543 544 545 546 547 548 549 550-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Bo
dy A
cc.
in m
/s²
Time in s
AMP Impulse
Pro
ba
bili
ty in
%
Psychometric Function
𝑃(𝑥) =1
1 + 𝑒𝑥−𝒄𝒔𝒂𝒔
1st 2nd 3rd
𝒂𝒔 = JND
𝒄𝒔 = x(P50%)
>
<
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Results of the JND
Human’s Perception of Vehicle Motion
• Fitting the psychometric function based on the probability of perceived
impulses
• Calculation the JND by evaluating the impulse intensity at the probability
of 50% and 75%
0 0.5 1 1.5 2 2.50
0.2
0.4
0.6
0.8
1
Relative Stimulus Intensity
Pro
ba
bilit
y o
f P
erc
ep
tio
n in
10
0%
Psychometric Function - Vertical Dynamics Impulse
50% JND
* measured impulse
- Fitted sigmoid fun.
75%
Evaluation of Chassis Components
V.
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Comparison of Vehicle Variants by the Perception of Road Impacts
Evaluation of Chassis Components
ToP and JND of vertical impulses
60 62 64 66-4
-3
-2
-1
0
1
2
3
4
Time in s
Bo
dy
Ac
c.z
in
m/s
2
60 62 64 66-4
-3
-2
-1
0
1
2
3
4
Time in s
Bo
dy
Ac
c.z
in
m/s
2
Threshold of Perception
Perceptible as impulse
● Vehicle 1 (orig.)
● Vehicle 1
• + 20 % Stiffness
• + 20 % Damping
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Comparison of Vehicle Variants by the Perception of Road Impacts
Evaluation of Chassis Components
ToP and JND of vertical impulses
60 62 64 66-4
-3
-2
-1
0
1
2
3
4
Time in s
Bo
dy
Ac
c.z
in
m/s
2
60 62 64 66-4
-3
-2
-1
0
1
2
3
4
Time in s
Bo
dy
Ac
c.z
in
m/s
2
61.75 61.8 61.85 61.9 61.951.7
1.8
1.9
2
Time in s
Bo
dy A
cc.z
in
m/s
2
Noticeable as difference
> JND
SummaryVI.
• Improved system understanding by subjective evaluation of driving
dynamics in early stages of the development process.
• Thresholds of perceptions can be used to evaluate driving dynamics
topics to get additional objective data and better correlations.
• Compared to real on-road tests new approaches and analysis can be
implemented.
• With this simulation environment the evaluation of driving dynamics can
be more experienced.
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Summary
Thank you!
phone +49 (0) 711 685-
fax +49 (0) 711 685-
University of Stuttgart
Pfaffenwaldring 12
D-70569 Stuttgart
Dipl.-Ing. Minh-Tri Nguyen
65889
65710
IVK – Institute of Internal Combustion Engines and Automotive Engineering