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Abstract ADAMS Users Conference 19-21 June, 2000, Orlando van Oosten, Pacejka, TNO
SWIFT-Tyre: An accurate tyre model for ride and handling studies also
at higher frequencies and short road wavelengths
Authors: Jan J.M. van Oosten, Hans B. Pacejka
As is well known, Magic Formula tyre modelling (MF-Tyre is a part of ADAMS/Tire) allows an
accurate and efficient description of tyre-road interaction forces required for any usual vehicle
handling simulation. When it comes to modelling of tyre behaviour at higher frequencies and
short road obstacles, which are important for vehicle ride assessment, advanced chassis controlsystems and chassis system vibrations, a more sophisticated approach is required.
In close co-operation with the Delft University of Technology and with involvement of nine
automotive companies, TNO has developed the SWIFT (Short Wavelength Intermediate
Frequency Tyre) model, which is based upon a rigid ring type of tyre model. The SWIFT model
is able to describe dynamic tyre behaviour for in-plane (longitudinal and vertical) and out-of-
plane (lateral, camber and steering) motions up to about 60 Hz, and for road obstacles with short
wavelength. For reasons of accuracy and calculation speed the SWIFT model has beenprogrammed as a semi-empirical model which is derived using advanced physical models and
dedicated high frequency tyre measurements to assess speed effects in tyre behaviour.
During the development of SWIFT much attention has been paid to validation of the model with
advanced high frequency tyre testing. The extensive testing programme showed that tyre model
parameter assessment by a modal analysis approach is certainly not sufficient for accurate tyre
F&M modelling.
Similar to the MF-Tyre module, the SWIFT-Tyre has been linked to ADAMS using a Standard
Tyre Interface and has been extensively validated with tyre measurements especially performedwith high frequency excitations. In addition robustness, user friendly-ness and backward
compatibility with MF-Tyre have been given high priority.
Typical applications of the SWIFT-Tyre module are:
active chassis control system development,
braking/driving behaviour during cornering on uneven roads,
vehicle ride assessment using sharp and short road obstacles, suspension vibration analysis (i.e. steering oscillations)
In this presentation the SWIFT tyre model will be explained as well as a comparison between the
model and the measurements will be shown. In addition, the use of the SWIFT tyre model in
ADAMS simulation models will be illustrated for ABS braking, while cornering over uneven
d
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SWIFT-Tyre
An accurate tyre model for ride andhandling studies for high frequencies and
short road wavelengths
Jan J.M. van Oosten
Hans B. Pacejka
International ADAMS User Conference
June 19-21, 2000, Orlando
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Content
Current DELFT-TYRE modelling
SWIFT-Tyre
the objectives
the model
experiments
validation
SWIFT modelling in ADAMS
Availability
Concluding
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Design and analysis
environment tosupport in
optimization of the
vehicle-tyre system
MF-Tyre
MF-MCTyre
MF-Tool+
MF-MCTool+
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DELFT-TYREcurrent models
MF-Tyre and MF-MCTyre:
Steady state and transient tyre modelling
for all basic vehicle handling studies up to 8 Hz
New version of MF-Tyre 5.2:
vertical stiffness depends on slip angle and long. slip
growth of tyre radius by rotational speed
rolling resistance depends on speed
improved combined cornering and braking/driving
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Next step:
SWIFT-Tyre
Short Wavelength Intermediate Frequency Tyre
Objective:
A general pragmatic tyre model (3D) for thedevelopment of active chassis control systems
and optimising vehicle ride properties
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SWIFT-Tyreapplications
Dynamic braking/driving (ABS/TCS)
Vehicle Dynamic Control (VDC/ESP)
Ride comfort & vibrations
Suspension and steering system design:
combined dynamic braking, cornering and ride
4 post rig ride testing
. All kinds of tyres
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Rigid Ring modelling for tyre belt vibrations
up to 60 Hz Semi-emperical for optimal accuracy and
calculation speed
Elaborate contact model for short wavelengthslip variations (wavelengths > 0.2 m)
Effective inputs for discrete obstacles
Magic Formula for slip force calculation
Validation with realistic tyre test data
SWIFT-TyreModel description
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SWIFT-TyreModel description
belt
wheel rim
Z
V
reff
eff
Weff
Fx
Fz
eff. road plane actual road surface
residual springs
*FyC
wheel plane
belt
Mz
VcV*
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SWIFT-TyreIn- and out-of-plane
Non-linear vertical force
Load and speed dependent belt frequencies
Tyre radius growth with speed
Vertical force influenced by contact pointdisplacement
Slip dependent transient behaviour
Eigenfrequencies of the tyre belt
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SWIFT-TyreShort obstacles
lengthening
response
swallowing
obstacles(enveloping)
filtered responseat axle
road profile
filteringunevenesses
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SWIFT-TyreShort obstacles
Effective input approach:
Road profile is transferred into effective inputs
Effective plane height
Effective plane angle
Vertical and long.
tyre forces
Rolling radius
variations
20002000
00
40004000
60006000
--100100-200-200
00 100100 200200
00
55
1010
positionposition[mm][mm]
verticalvertical
loadload
[N][N]
effectiveeffective
planeplane
heightheight
[mm][mm]
trapezoid cleattrapezoid cleat
10 mm10 mm30 mm30 mm
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SWIFT-TyreExperiments
&
Validation
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F&M testingfor SWIFT parameters
Dynamic tyre testing for SWIFT parameters
(at different loads and speeds)
dynamic braking
cleat testing
dynamic cornering
effective input tests
Model analysis approach
Identified frequencies not representative for tyre
behaviour under driving conditions
Not suitable to assess speed and load effects
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ValidationStep wise brake torque input
0 0.5 1 1.5 2 2.5-500
0
500
1000
1500
2000
2500
3000Longitudinal force [N]
time [s]
measuredSWIFT-Tyre
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ValidationStep wise brake torque input
amplitude / [N/Nm]F Mx b
frequency [Hz]
phase [deg]
0
10
20
30
-180
-90
0
90
180
0 20 40 60 80 100
in-phaserotational
mode
out-of-phaserotational
mode
measuredSWIFT-Tyre
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ValidationVertical force when rolling over cleat
--22000000
--11550000
--11000000
--550000
00
550000
11000000
11550000
22000000
time [s]time [s]-0.05-0.05 0.00.0 0.050.05 0.100.10
time [s]time [s]-0.05-0.05 0.00.0 0.050.05 0.100.10
time [s]time [s]-0.05-0.05 0.00.0 0.050.05 0.100.10
VV= 25 km/h= 25 km/h VV= 39 km/h= 39 km/h VV= 59 km/h= 59 km/h
Vertical forceVertical force [N][N]
measuredSWIFT-Tyre
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ValidationVertical force when rolling over cleat
00
2200
4400
6600
frequencyfrequency [Hz][Hz] frequencyfrequency [Hz][Hz] frequencyfrequency [Hz][Hz]00 5050 100100 150150 00 5050 100100 150150 00 5050 100100 150150
verticalvertical firstfirst
flexibleflexible
modemode
22ndnd??
VV= 25 km/h= 25 km/h
VV= 39 km/h= 39 km/h
VV= 59 km/h= 59 km/h
Auto-Auto-spectral density vertical forcespectral density vertical force [N/Hz][N/Hz]
measuredSWIFT-Tyre
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ValidationLong. force when rolling over cleat
-4
-3
-2
-1
0
1
2
3
4
time [s]-0.05 0.0 0.05 0.10
time [s]-0.05 0.0 0.05 0.10
time [s]-0.05 0.0 0.05 0.10
V= 25 km/h V= 39 km/h V= 59 km/h
Wheel velocity during passage over a trapezoid cleat
measuredSWIFT-Tyre
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ValidationLateral force due to slip angle step
0.2 0.4 0.6 0.8 1 1.2 1.4-500
0
500
1000
1500
2000
2500
3000Lateral force [N] (detail) Fz=4000 N, V=92 km/h
measuredSWIFT-Tyre
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SWIFT in ADAMSimplementationNew Standard Tyre Interface:
More than 2 states possible At least 2 x faster
(benchmark with MF-Tyre)
More flexible
GUI allows change of tyre
and road parameters
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SWIFT in ADAMSexample
Quarter vehicle model
Tyre rolling over cleats
with 6 slip angle
ABS-pulse braking
Vertical load variationsduring cornering
Interaction between
steering and braking
forces
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SWIFT in ADAMSexample
10 15 20-2000
0
2000Road steps input
Fx[N]
10 15 20-2000
200400600800
Fy[N]
10 15 200
5000
Fz[N]
10 15 20
0
0.02
0.04
Height[m]
Travelled distance [m]
2 2.5 3 3.5-6000-4000-20000
20004000
Pulse brake input
Fx[N]
2 2.5 3 3.5500
600
700
Fy[N]
2 2.5 3 3.54000
4500
5000
Fz[N]
2 2.5 3 3.5
-1000
-500
0
Torque[Nm]
Time [s]
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ABS simulationcomparison of tyre models
1.5 2 2.5 3 3.5 460
80
120Wheel speed and brake torque during ABS simulation with various tyre models
1.5 2 2.5 3 3.5 4-1000
-500
0
500
1000
Time [s]
Braketo
rque[Nm]
100
Wheelrotationalspee
d[rad/s]
SWIFT-Tyre
MF-Tyre, Transient
MF-Tyre, Steady State
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Availability
Now:
SWIFT-Tyre
SWIFT-Datasets
First half 2000:
SWIFT-Tool
SWIFT-Fit
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Concluding...
SWIFT is next step in DELFT-TYRE
modelling
robust, fast and accurate tyre modelling for
ride and advanced chassis control applications
validated with advanced dynamic tyre testing
parameter assessment under realistic driving
conditions
allows state of the art tyre modelling by any
ADAMS user
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