13 TNO Swift Tyre Ride Handling

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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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2000 International ADAMS User Conference

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



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

Documents

13 TNO Swift Tyre Ride Handling