Slide 1

ComparisonCi
off O
On-roadd&L
Laboratory-basedb tbd
Rolling Resistance Measurements
Dr. Jürgen Bredenbeck
Dr. Rahul Ahlawat, Dr. Michael Smith, Mr. Tatsuo Ichige Mr. Katsuhiko Furuya

Tire Meets Science
11-12 September 2013, Aachen, Germany

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Slide 2Content•
•
•
•
•
•

Objective
On-Road Measurement
On-Road Results
In Door Testing
In Door Results and Comparison
Summary

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Slide 3

Objectives
j1
1.

Comparison
Cioff on-roadd rolling
lli resistanceimeasurements with standardized indoortesting

22.

Comparison of standardized testing on
flat-belt and drum machines

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Slide 4Content•
•
•
•
•
•

Objective
On-Road Measurement
On-Road Results
In Door Testing
In Door Results and Comparison
Summary

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Slide 5

On-Road Rolling Resistance Measurements
Coast-down method

Instrumented trailer

Instrumented vehicle

e.g. VTI, Sweden [9, 12]e.g. FKFS, Germany,BASt, Germany,
HUT, Finland [6]e.g. A&D, Japan

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Slide 6

On-road Measurements
Testt VTVehicle:
hi l• Instrumented Mini Cooper S• Proving ground in Tochigi
Tochigi, Japan
Test Tires:• Rear left(RL) & rear right(RR)
StopStart• Bridgestone Sneaker2 (205/55 R16 91V)
• 250 kPa (capped)
Test Procedure:
pat different speedsp• Round course 6 repeats• Selection of straight, constant speed phasefor data analysis
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Slide 7Vehicle Instrumentation I
A&D Wheel force Sensor (WFS)••••••

Unique design
Distributed force bridges with model based
decomposition to get orthogonal force components
low cross sensitivity
low temperature sensitivity
high sampling rate
Hi h AHigh
Accuracy
0.1% resolution(6N or 1.8Nm)

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Slide 8Vehicle Instrumentation II•

DDopplerl VVelocityl i SSensor– Vehicle velocity•

GPS Sensor & In-vehicle Network– vehicle longitude, latitude, altitude, and ECU CAN communication•

A&D Wheel Position Sensor– 6 degrees of freedom of the tire relative to chassies•

Inertial Sensor– vehicle roll, pitch and yaw•

Digital Signal Processing & Acquisition– 100Hz sampling of all signals

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Slide 9

Tire Rolling Resistance•RollingR
lli resistanceiiis createddin the Tire patch– Tire Patch shows an asymmetricycontact
Pressure distribution, which canbe substituted by:• a total contact force F and• a moment MR– MR appears
pp
as resistance force R on
the wheel hub
MR = R ∙ r
r: dynamic rolling radius

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Slide 10

Mathematical Formulation
MR = R ∙ r[ ][1]
Torque equation:J ∙ ώ = ‐ My ‐ MR + FA ∙ rwith [1]:J ∙ ώ = ‐ My ‐ R ∙ r + FA ∙ r[2]Force equation:m ∙ a = Fx ‐ FA FA = Fx ‐ m ∙ a[3]Kinematic condition:v=ω∙r
r=v/ω
[4]r:
Rolling radius[3] in [2]:J ∙ ώ = ‐ My ‐ R ∙ r + ( Fx ‐ m ∙ a ) ∙ r
φ, ω, ώ: Angle, angular speed/R = Fx ‐ m ∙ a – ( 1 / r ) ∙ (J ∙ ώ + My )acceleration of wheel
x, v, a:with [4]:Distance, speed,
acceleration of wheel
R = Fx ‐ m ∙ a – ( ω / v ) ∙ (J ∙ ώ + My ) J,J m:
torque inertia/massii /offwheel
My ,Fx: Torque/force on wheelhub
D t
Determinedi db
beforefth
the EExperimentit
FA :Adhesive force

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Slide 11

Parameter Determination• TireTi mass can bbe ddeterminedti dbbylifting the wheel. WFS will show themass• Tire rolling inertia is determined using
free load rotating wheel inacceleration and deceleration
condition• Measurement items– Tire angular speed ω [rad/s]– Angular acceleration ώ [rad/s2]– WheelWh l ttorque M
Myfree [Nm][N ]• Rolling inertia formula:Jt My freeProprietary and Confidential, A&D Technology, Inc.

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Slide 12

Data selection••

Data iis filtered
Dfild at 5Hz5Hvarious signals are analyzed to find atime pperiod having
g constant speed,p,straight line vehicle motion

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Slide 13Content•
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•
•
•

Objective
On-Road Measurement
On-Road Results
In Door Testing
In Door Results and Comparison
Summary

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Slide 14

On-road Rolling Resistance Force• Three speeds• 6 tests for each speed• Calculation applied to time data of Fx and My according to introduced
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Slide 15

Mean Rolling Resistance Forces (RRF)•••

Averaging the time record data for individual speeds
Rolling resistance force does not vary with significantly with speed
It is possible to have good repeatability for on-road measurements
Mean RRF=85.4 N
σRRF= 1.818N
σRRC= 0.65 N/kN

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Mean RRF=84. 9 N
σRRF= 2.3 N
σRRC= 0.84 N/kN

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Mean RRF=84.6 N
σRRF= 1.919N
σRRC= 0.70 N/kNSlide 16Content••••••

Objective
On-Road Measurement
On-Road Results
In Door Testing
In Door Results and Comparison
Summary

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Slide 17

Indoor Testing Equipment•A&D Standard
S d d Rolling
R lli resistancei
test rigi– 2m Drum, Steel covered•

A&D Dynamic Flat Belt Test Rig– Steel Belt•

Force Measurement utilizing A&D Hub Sensor
Sh– MBS Sensor
approach– Fx: 300N ±0.3N– Fz: 15kN ±20N
– Machines Meet Reference Lab repeatability
criteria

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Slide 18

Test Procedure for Indoor Testing
Follow ISO28580 Test Procedure• 3h thermalhl conditioning
di i i• 30 min warm up• Test conditions: Speed 80 km/h, 210kPa (capped), 80% max Load
• Skim Test at 150N
Measurements:• Spindel Force• Loaded Tire radiusCalculation of:• Surface Force• Parasitic Force• Rolling resistance Force• Temperature correction• Rolling resistance Coefficient• Curvature correction [3], [5]Proprietary and Confidential, A&D Technology, Inc.

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Slide 19Content••••••

Objective
On-Road Measurement
On-Road Results
In Door Testing
In Door Results and Comparison
Summary

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Slide 20

Comparison of Results

On‐Road (Fz=2.73kN)
Indoor (Fz=4.82kN)

Drum Machine
Clark’s Curvature
Correction
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Flat‐belt Machine

Slide 21

Potential Reasons for Differences••••

Tire alignment
Tili((camber,b toe)) on theh roadd [4]Roughness of road surface (unevenness, macrotexture) [7, 10-12]• Energy dissipation in the suspension• Dynamic vertical deflection of the tire leading to additional
hysteresis• Additional friction losses due to microslip
Uncontrolled environmental factors such as temperature andinflation pressure
Measurement errors such as loaded
tire radius

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Slide 22

Indoor Testing Results

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Slide 23

Repeatability Results••Excellent
Ellrepeatability
bili iis achieved
hid ffor bbothhd
drum & flflat-belt
b l machines
hiTire ranking is preserved during iterative testing

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Slide 24

Rank Preservation••

Drum and Flat-Belt machines rank tires differently
yFlat-Belt results are lower than drum and curvature corrected [3, 5]
drum machine results

[5]
[3]

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Slide 25

Temperature Differences
Drum acts as a heat sink whereas belt gets heated up

Flat belt machine
Flat-belt

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Slide 26

RRF vs RRC••

Relative
Rl i ranking
ki iis not preservedd ffor
both RRF and RRCRanking
g based on RRC and RRF
will be different as they represent
different things

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Slide 27Summaryy•

Repeatable on-roadon road measurements are possible•

Indoor measurements offer superior control oftest parameters and very high repeatability•

Measured losses are significantly less than what
we see on the real road•In door testing should include more test variables(such as camber, toe, slip, etc.) to get a closer
approximation of in-vehicle
in vehicle & on-roadon road tireperformance•

Relative tire rankingsg from drum and flat-beltmeasurements are not necessarily equivalent

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Slide 28

Acknowledgementsg••••

On-roadOdddatat acquisition:i iti– Takayasu Sasaki– Yuuki Sakurai– Masaaki Banno– Hiroki Yamaguchi
Indoor data acquisition:– Atsuo Murakami– Tomikazu Oyama– Masaki Takahashi
Kenji Sato, A&D Company, Japan
Dr. Rahul Ahlawat

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Slide 29

References
1.

“Passenger car, truck and bus tyres – Methods of measuring rolling resistance – Single point tests and correlation ofmeasurement results”, ISO/FDIS 28580, 2009
2 Hall & Moreland
2.
Moreland, “Fundamentals
Fundamentals of rolling resistance”
resistance , Rubber Chemistry and Technology,
Technology July/Aug 2001
3. Freudenmann, Unrau & El‐Haji, “Experimental determination of the effect of the surface curvature on rollingresistance measurements”, Tire Science & Technology, Vol. 37, No. 4, 2009
4. “The pneumatic tire”, Chapter 12: Rolling Resistance, NHTSA, 2006
5. S.K. Clark, “A handbook for the rolling resistance of pneumatic tires”, 1979
6. Leinonen & Juhala, “Development of measurement equipment for measuring tire rolling resistance on road”, 8thbiennial ASME conference on engineering systems design & analysis, July 4‐7, 2006, Torino, Italy
7 Popov,
7.
Popov Cole,
Cole Winkler & Cebon
Cebon, “Laboratory
Laboratory measurement of rolling resistance in truck tyres under dynamic verticalload”, Proceedings of the Institute of Mechanical Engineers, Vol. 217, Part D: Journal of Automobile Engineering,2003
8. Petrushov, “Coast down method in time and distance variables for tire rolling resistance determination”, SAE 2009‐
01 0072
01‐0072
9. Sandburg & Ejsmont, “Noise emission, friction and rolling resistance of car tires – Summary of an experimentalstudy”, National conference on noise control engineering, Dec 3‐5, 2000, Newport beach, California
10. Gillespie, “Measuring road roughness and its effects on user cost and comfort: A symposium”, Issue 884, 1985
11. Meyer, “Surface characteristics of roadways: International research and technologies”, Issue 1031, ASME, 1990
12. Karlsson, Hammarström, Sörensen & Eriksson, “Road surface influence on rolling resistance ‐ Coastdown
measurements for a car and an HGV”, VTI, 201113 Salaani et al13.
al., “NHTSANHTSA tire rolling resistance test development project – Phase I”
I , Paper Number 09‐0300
09 0300

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