2014 Vehicle Dynamics Objectiv Part 1

8/12/2019 2014 Vehicle Dynamics Objectiv Part 1

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06/2013 Stefan Eitzinger, MSF/Graz 1Disclosure or duplication without consent is prohibited

Vehicle dynamicsobjective assessment part 1

Introduction

vehicle dynamics in the development process

subjective evaluation vs. objective evaluation of vehicle dynamics

Measurement Equipment

measurement of command signals (steering wheel angle, pedal position)

equipment for measurement/analysis of cars mechanical behavior (toe-,

camber angle, wheel speed)

measurement of total vehicles response (yaw rate, side slip angle, roll

angle)

Testing Procedures

longitudinal dynamics (straight ahead behaviour)

lateral dynamics (cornering behaviour)

lateral dynamic transfer characteristics (lateral transfer behaviour)

driving stability tests (roll- and yaw stability)


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Vehicle dynamics in the development process

Prototype

Design

Simulation

Test Rig

Virtual Model

On-Vehicle Objective TestsSubjective Rating

Validation of Geometry,

Kinematics and Compliance

Verification of

Specifications

Optimisation loop

Release

Optimisation loop

Validation of Simulation Model

Chassis Concept


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Subjective Rating Objective Testing

L en kr ad wi nk el D im . MW SA MW SA

M it te lw er t ( 0, 5- 4) s G ra d 3 1, 56 3 ,0 8 2 9, 42 2 ,9 5

Giergeschwindigkeit

Max imalwert Grad/s 10, 48 0,48 10, 66 0,51Peak -Res pons e-Time s 0,29 0,04 0,34 0,0590% Res pons e Time s 0,21 0,08 0,25 0,11bers chwingweit e % 24, 19 3,45 25, 13 4,66S ta ti on r we rt ( 3- 4 s ) G ra d/ s 8 ,2 8 0 ,1 2 8 ,3 4 0 ,1 4G ie rve rs t r kun gs fa k to r G ra d/ s /G ra d 0 ,2 6 0 ,0 3 0 ,2 9 0 ,0 3

Querbeschleunigung

Peak -Res pons e-Time s 0,56 0,11 0,69 0,1390% Res pons e Time s 0,33 0,08 0,41 0,11S tat ionr wert (3- 4 s ) m /s 4, 01 0, 02 4, 02 0, 04

Schwimmwinkel

S tat ionr wert (3- 4 s ) G rad 0, 74 0, 24 1, 00 0, 26

Bewertungsma

TB-Wert Grad*s 0,22 0,08 0,35 0,12TBN-Wert - 7,35 1,18 8,92 1,42

t ei lb el ad en v ol lb el ad en

Vehicle dynamicsOn Vehicle Tests

+ Driver-independent comparison of different vehicles

+ Results can be reproduced with high conformity

+ Lower requirements on the capabilities of the testdriver

+ Vehicle-comparison possible even after a long time

+ Results can be used for validation of simulated

results

+ No equipment required

+ Immediate results

+ Highest sensitivity in direct comparisons


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definition of best-in-class

proposals for improvements

Tools:

rating sheets, performance tables

on-vehicle tests (professional /normal driver)

spider diagrams

specific target values for

reproducible and comparable

driving maneuvers

Subjective Objective

Tools:

catalogue of maneuvers

selection of target-values

VD-measurements

Calculation of selected target-

values

40 Cornering behaviour

40 1010 Steering wheel angle gradient at 4 m/s R=100m (ISO 4138) 4.55/m/s40 1020 Self steering gradient at 4 m/s R=100m (ISO 4138) 0.28/m/s

40 1030 Side slip angle gradient at 4 m/s R=100m (ISO4138) 0.31/m/s

40 1040 Roll angle gradient (ISO4138) 0.4/m/s

40 1050 Maximum roll angle R=100m (ISO4138) 3.53

40 1060 Maximum lateral acceleration R=100m (ISO4138) 8.8m/s

40 1080 Maximum yaw amplification (MSF internal Standard) 0.26/s

40 1090 Minimum yaw amplification (MSF internal Standard) 0.21/s

40 1100 Yaw amplification strictly monotonous decreasing from vch (MSF internal Standard) yes

Chassis development - targets


5/1806/2013 Stefan Eitzinger, MSF/Graz 5Disclosure or duplication without consent is prohibited

steering

throttle position

brake force

toe-in

camber

wheel travel

brake pressure

wheel speed

pitch angleroll angle

yaw angle speed

accelerations in all axis

lateral velocity

Measuring a vehicles behaviour - systematics

controlled system

(vehicle properties)

control response

(vehicle reaction)

command signal

(manoeuvre presetting)

During vehicle dynamics measurements the driver usually presets the input butdoes not react to the vehicle's behaviour or path. This system of driver and vehicle

can be seen as an open loopcontrol system. Not so when driving on public roads.

Drivers actions Reaction of the carMechanical behaviour



Chassis: original setup (except prototypes)

Loading: > partially loaded (driver, measurement equipment, design load)> fully loaded (gross vehicle weight)

Tires: original equipment tires, previously driven (150 km)

Tire pressure: according manufacturer's data 0,05 bar (cold)

Test track: flat, dry, const. friction coefficient

Environment: max. wind speed 5m/s

Testing conditions

To ensure reproducible results the driver's influence must be

minimized. Vehicle, test track and environmental conditions have tobe in defined conditions (ISO 15037-1). The following conditions must

be fulfilled if not explicitly defined otherwise.



roll: rotation round XV -axis ( )

pitch: rotation round Y-axis ( )

yaw: rotation round ZE -axis ( )

X

Y

Z

In all measurements the motion variables (velocities, accelerations,

rotational speeds) are measured in the vehicle fixed intermediate

coordinate system. This eliminates the gravitational influence due to

pitching and rolling in the measured accelerations.

Intermediate vehicle fixed coordinate system:

Coordinate systems according DIN ISO 8855

earth fixed coordinate system (XE, YE, ZE)

vehicle fixed coordinate system in COG (XV, YV, ZV)

vehicle fixed intermediate coordinate system in

COG (X, Y, Z) (X-Y plain is parallel to XE-YEplain)

Rotational degrees of freedom in the vehicle

fixed coordinate system:



In DIN ISO 8855 the motion variables of vehicles are defined. The sketch below shows the most

important of them for a left turn manoeuvre under Ackermann-condition (ay



Vehicle dynamics measurement equipment


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1.) Measurement steering wheel / Steering Robot

steering angle

steering torque

steering velocity

Measuring of command signals (1)

Controled system Control responseCommand signal

measurement steering wheel from

www.kistler.com(closed loop tests)

steering robot from

www.abd.uk.com

(open loop tests)
http://www.kistler.com/http://www.abd.uk.com/http://www.abd.uk.com/http://www.kistler.com/


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Measuring of command signals(2)

clutch-, brake pedal force

3.) Pedal force sensor

www.rieger-sensortechnik.de

2.) Cable pull position sensor

travel measurements

(pedal-, wheel travel...

Controlled system Control responseCommand signal

www.celesco.com
http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/


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1.) Autocollimator

toecamber

steering kinematics

Measuring of values used for system analysis (1)


www.rudolph-optics.com/
http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/


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3.) Wheel Speed Sensor

high resolution wheel speed (1024 pulses/rev)

Measuring of values used for system analysis (2)


www.gregory.de
http://www.celesco.com/http://www.celesco.com/http://www.celesco.com/


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www.corrsys-datron.deg...grid spacing

gChanges of brightness on the road

surface generates a speed

proportional frequency in the photo

electronics of the speed sensor. For

sensing lateral speed the grid is V-

shaped.

1.) Optical speed sensor

longitudinal speedlateral speed

sideslip angle


Measuring of vehicles response values (1)

www.kistler.com
http://www.kistler.com/http://www.kistler.com/


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distance body - ground

pitch angle (computed)

roll angle (computed)

3.) Laser distance sensor


AL

ah

av

atan[(ah-av)/AL]


www.drwehrhahn.de
http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/


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pitch rate

roll rate

yaw rate

pitch angle

roll angle

yaw angle

longitudinal accelerationlateral acceleration

vertical acceleration

path curve coordinates

curve radius

4.) Inertial measurement unit


www.imar-navigation.de/

http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/


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Data Recording

www.dewetron.com, www.ni.com, www.datatranslation.com, www.panasonic.com, www.vector-informatik.de

vehicle-CAN

meas-CAN

steering robot,

meas. steering wheel

odometer

(speed sensor)

laser-

distance sensor

gyro platform

autocollimator

cable pull-

sensor

further analogue sensors

trigger, force sensors, ...

analogue to

CAN conv.
http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/http://www.kistler.com/


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Video: Steering Robot Demo
http://localhost/var/www/apps/conversion/tmp/scratch_9/Filme/Lenkroboter%20und%20HAL.mpg

Documents

2014 Vehicle Dynamics Objectiv Part 1