HANDLING QUALITY OBJECTIVE EVALUATION OF LIGHT … › conf › 08vdx_conf › ... · • Test...

Stuttgart, May 6, 2008 1

PRESENTING AUTHORM. PesceCRF, VEHICLE DYNAMICS

CO-AUTHORSD. Gostoli, A. Fagiano - IVECO, QUALITY EVALUATION, CS & QUALITYM. Mazzarino - IVECO, TECHNICAL INNOVATIONS. Data, M. Grillo - CRF, VEHICLE DYNAMICSC. Randazzo - CRF, PRODUCT QUALITY

HANDLING QUALITY OBJECTIVE EVALUATIONOF LIGHT COMMERCIAL VEHICLES

Stuttgart, May 6, 2008 Handling Quality Index LCV 2

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Main goals


Main goals

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Quality Indexes approach

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CUSTOMER ORIENTATION IN VEHICLE DESIGN:Methods/Tools Development and Application for target setting, deployment and achieving

Voiceof

Customer

Voiceof

Customer

ComponentsTarget

Achieving

ComponentsTarget

DesignSpecifications

DesignSpecifications

VehicleTarget Setting

VehicleTarget Setting

Sub-systemsTarget

Deployment

Sub-systemsTarget

Deployment

Purchase Criteria & Perceived Quality

Perceived Qualitymeasurements (Q.I.)

Deplyoymentprocedure & simulation tools

Achieving


• Panel Test: professional and non professional drivers in free driving conditions

• Questionnaire: subjective assessments expressed on different levels coherent with the performance tree

• Evaluation on a panel of different vehicles

• Instrumented Vehicle• Test Procedure: standard

maneuvers carried out on the basis of specific requirements

• Objective Parameters: acquisition and analysis of road data for the identification of performance indicators



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1994: first handling (IQH) and steering feel (IQS) metric for Fiat cars

Continuous development according to Fiat Group experience & ISO TC22/SC9 New Work items:

- limit handling- rollover, NHTSA- uneven roads- power on / power off - braking

Extension vs. Light & Heavy Commercial Vehicles

Extension vs. Agricultural Tractors

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References about objective handling assessment in Fiat Group



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INDEX


OBJECTIVE PARAMETERSCORRELATION vs.

SUBJECTIVE EVALUATIONS

OBJECTIVE PARAMETERSIDENTIFICATION

STATISTICAL ANALYSISON SUBJECTIVE

EVALUATION

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Project plan

EXPERIMENTALMEASUREMENTS

INSTANDARD MANOEUVRES

VEHICLE HANDLING EVALUATION QUESTIONARY


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INDEX


Subjective evaluation

1. Questionnaire definition and Jury Selection

2. Statistical spread analysis to search outlier judge or not significant aspects

3. Partial rating determination

4. Correlation analysis to evaluate the influence that every partial rating has on the global one.

Goals:

• Definition of a questionnaire to be used for Subjective Handling tests.

• Building of the Db of the average subjective ratings, that will be correlated with objective measurements.

• Estimation of the weights of the partial aspects on the global handling evaluation.


Questionnaire definition and Jury Selection

Jury Selection• About 15 Drivers• Professional and non

professional drivers• Selected from IVECO,

FGA, CRF


Unipolar aspect Bad Good

Example: On center quality

Bipolar aspect Too high Optimum Too small

Example: Steering wheel torque in normal driving


0.3

1.1

1.4

2.6

6.8

8.7

17.4

17.9

21.0

32.1

35.4

48.2

0 10 20 30 40 50

Free steering oscillation after cornering

Steering wheel activity

Quickness in car response

SW Torque in Normal Driving

Motricity in turn

Roll motion velocity

Car feedback progressiveness

Roll motion

On-centre quality

SW Torque in Parking

GLOBAL HANDLING EVALUATION

Aerodynamics Interaction sensitivity

Statistical spread analysis

Search of outlier judge Search of more meaningful aspects

More meaningful aspectsDriver more aligned at the average

evaluation

Driver more different from average evaluation



Partial ratingsAverage evaluations of partial aspects by the whole jury for each vehicle

0

2

4

6

8

10SW Torque in Parking

SW Torque in Normal Driving

On-centre quality

Free steering oscillation after cornering

Steering wheel activity

Quickness in car responseCar feedback progressiveness

Aerodynamics Interaction sensitivity

Motricity in turn

Roll motion

Roll motion velocity

Full load configuration



Too high [=-5] � Optimal [=0] � Too small [=5]

Partial rating example: Roll Motion

Full load

Empty vehicleEvaluation of global roll angle during turning in a normal driving without rapid transient maneuvers (“quasi steady” conditions).


Vehicle AVehicle BVehicle CVehicle DVehicle E

Vehicle AVehicle BVehicle CVehicle DVehicle E


Handling Global Evaluation in Normal Driving

Full load

Empty vehicle

Global Rating Weights of the partial aspects

Cluster 1 (3 Aspects)

Cluster3 (1 aspect)

Cluster 4(1 aspect)

Cluster 2(2 aspects)

19%

15%

11%55%

A principal component analysis approach has been applied for the identification of the main clusters in subjective perception.Some aspects are not relevant from a statistical point of view.


Vehicle A

Vehicle B

Vehicle C

Vehicle D

Vehicle E

Vehicle A

Vehicle B

Vehicle C

Vehicle D

Vehicle E


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INDEX


• Vehicle setup• Test procedure• Post-processing and Example of some results

Measured signals and measurements/filtering procedures comply to ISO 15037-1

Measured variables for quality indexes are:• STEERING WHEEL ANGLE• LATERAL ACCELERATION• YAW RATE• SIDE SLIP ANGLE• STEERING WHEEL TORQUE• ROLL RATE• THROTTLE POSITION• VEHICLE SPEED

Additional signals are acquired for a more complete analysis: longitudinal acceleration, pitch rate, suspension travel, height sensors

Objective evaluation


• Vehicle setup

• Test procedure• Post-processing and Example of some results

Handling road tests (Balocco & La Mandria tracks):

• Steady state circular test 40 m (ISO 4138)

• Constant speed test 80 km/h (ISO 4138)

• Step steer input 100 km/h (ISO 7401)

• Free steer control test 100 km/h (ISO 17288)

• Sweep input 60-100 km/h – 0.25, 0.4, 0.55 g (ISO 7401)

• Sinusoidal input 60-120 km/h – 0.2 Hz – 0.25 g (13674-1)

• Complete steer cycles with vehicle in standstill and at low speed

Curva di raggio40 / 100 mCurva di raggio40 / 100 m

δδδδV1

δδδδV2δδδδV3

100km/h

δδδδV1

δδδδV2δδδδV3

100km/h



• Vehicle setup• Test procedure

• Post-processing and Example of some results

Main calculated parameters:

• Steady state behaviour,

• Transient gains,

• Time delay,

• Hysteretic cycles.

Regarding:

• Lateral dynamics,

• Roll response,

• Steering wheel torque.

In different conditions of:

• Vehicle speed,

• Steering wheel amplitude,

• Steering wheel frequency.

Steady state

-8

-7

-6

-5

-4

-3

-2

-1

0

0.0 0.2 0.4 0.6 0.8Ay [g]

0

10

20

30

40

50

60

70

80

0.0 0.2 0.4 0.6 0.8

Ay [g]

Sideslip angle [deg]

Steering wheel angle [deg]

Vehicle AVehicle B Vehicle CVehicle D

-0.20-0.18-0.16-0.14-0.12-0.10-0.08-0.06-0.04-0.020.00

0 1 2 3 4

Freq [Hz]

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 1 2 3 4

Freq [Hz]

Transient responseYaw rate vs. Steering Wheel

Gain [1/s]

Time delay [s]



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INDEX


The process for Index identification

1

1: Partial indexSubjective evaluations are correlated with measured parameters starting from the IQH car experience.Weights are modified and additional parameters are included in the model when necessary to improve the correlation level.A final rating in 0-10 scale is obtained.

2: Global quality indexStarting from the weights of partial aspects on global determined from subjective evaluation, a refinement is done in order to compensate the aspect not yet covered by partial objective indexes.

2

Quality Index (IQH)


IPI - LCV Response progressiveness

0

1

2

3

4

5

6

7

8

9

10

-2 0 2 4 6 8 10

Partial ratings: Correlation with Subjective Evaluations

LCV feedback progressiveness

Ipi = A + B * [C0 + C1*Param1 + C2*Param2 + C3*Param3]

Parameters:Param1: time delay between yaw rate and lateral acceleration calculated in manoeuver frequencysweep, at speed 60 kph, linear range.

Param2: …Param3: …

tr(0.5)ThpDv; 18%

AlfaR0; 58%

mTrPsip50; 24%

Param124%

Param218%

Param3 58%

R2=0.91

Subjective Rating

Obj

ectiv

e In

dex

� Full load

� Empty

Quality Index (IQH)


IVC_ICO - Roll motion

4

5

6

7

8

9

10

-5 -4 -3 -2 -1 0 1

ISP - Steering torque in parking

4

5

6

7

8

9

10

0 2 4 6 8 10

ISM - Steering torque in normal driving

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

IDIR - On center quality

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10

IAV - Steering wheel activity

0

1

2

3

4

5

6

7

8

9

10

-5 -4 -3 -2 -1 0

IRV - Quickness in LCV response

0

1

2

3

4

5

6

7

8

9

10

-5 -4 -3 -2 -1 0

IPI - LCV Response progressiveness

0

1

2

3

4

5

6

7

8

9

10

-2 0 2 4 6 8 10Subjective Rating

Obj

ectiv

e In

dex

� Full load

� Empty

R2=0.73

R2=0.79 R2=0.91

R2=0.90 R2=0.95

R2=0.72

R2=0.89

ICOVC: Roll motion ISP: Steering Wheel Torque in Parking

ISM: Steering Wheel Torque in Normal Driving

IDIR: On-centre quality

IAV: Steering wheel activity

IRV: Quickness in LCV response

IPI: LCV response progressiveness

Partial ratings: Correlation with Subjective Evaluations

Quality Index (IQH)


R2=0.91

Weight of Partial ratings vs. Global Index

Subjective Rating

Obj

ectiv

e In

dex

� Full load

� Empty

I 120%

I 23%

I 314%

I 420%

I 530%

I 610%

I 73%

Global handling rating: Correlation & Composition

Quality Index (IQH)

IQH - Global handling rating

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10


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Conclusions and Next steps

HANDLING QUALITY OBJECTIVE EVALUATION OF LIGHT … › conf › 08vdx_conf › ... · • Test...

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