Headway Spacing Model for

a Heavy Vehicle Based on

Experimental Data

L. NOUVELIERE

D. STANCZYK

B. DERVIEUX A. RABEHI

C. MVOME B. PELAUD

Introduction

• Strong decrease of the number of fatal

accidents on roads (France)

– The typologies of accidents do not seem to

evolve very much

– The driver/infrastructure stay at the origin of

numerous failures

• ABS, ESP, … improve the driving but only

correct a deteriorated situation, when the

driver introduces a corrective action

– Contribution of predictive systems

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Introduction

• Road automation solution

– To help the driver to better drive regarding the

current driving situation by sharing the driving

action between Man-Machine

– Road safety, eco-driving : a Vehicle-

Infrastructure-Driver interaction

– ABV project : Low speed automation of

vehicles

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ABV project

• French ANR project (5.5M €)

• Aims at developing ADAS with copilot

systems for light and heavy vehicles

whatever the speed with special scenarios

at low speed

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ABV project

• Many technological evolutions make the

driving automation possible

– High increase of the number of sensors

• More information about the vehicle and its

environment

– Computation power

– Control of the actuators and driver’s feedback

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ABV project

• Development of several technological

modules

– Perception

– Trajectory planning

– Control

• Copilot system

• Low fuel consumption

Safe itinerary definition

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Safe itinerary definition

• Offers :

– a safe and low energy trajectory

– a driving assistance in the longitudinal and

lateral modes

– some services from road managers, vehicles

flow managers, …

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Safe itinerary definition

• Needs :

– Perception performance

– Fast trajectory planning

– Road/Vehicle interaction (speed limit in

curves, legal speed, eHorizon, …)

– Control inputs and robust control for several

categories of vehicles (light, heavy, …)

• Longitudinal mode :

Speed, safe headway spacing for HV

Safe ADAS with low energy consumption

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Safe Distance

• Relating the individual behavior of a given

driver to the safety requirements

associated with traffic conditions

– Vehicle model

– Braking distance

– Safe distance

– Headway spacing

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Vehicle Modeling

• Non-linear dynamic model

• First order braking and engine actuators

• Simplified gearbox model introduced in the

model

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ac

acacac

br

brbrbr

rbrreee

xr

TTT

TTT

hFtTi

isathKRtTtI

txci

isatKtxM

*

*max

2

max

))()(.()()1()(

0)()(.)(

0)(* tTbr

0)(* tTac

))(),(max(

)()(

txtRh

txtRhi

e

e

Braking distance

• Initial condition : at time t0, the vehicle

brakes with Tbr*

• Braking distance performed before the

vehicle stops :

• It is looked for ts such that:

• Braking distance:

)1()()()(0)(0)( 00

0000000 iRh

VtVtxxtxtTtT eacbr

0)( 0 sttx

00

*

0 )(,...),,( xttxKTVdd srbrss

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Headway spacing

• Safe distance and headway spacing :

].4

)(3

))2

)(

)(2

)((

2[

)(3/

1

max3

0max2max2

0

22max

0

2max

max*2max*22

max

0

2

0max

220min

*

02

0

2

0

*

max

ss

s

s

tVK

ictV

I

hRctMV

tF

th

T

h

tT

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K

i

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IVdd

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VI

VhchFTt

r

a

e

as

sf

sbrbrbrbr

ere

ets

brbre

afbr

s

)()()().2

1()()),((

~ 22000 txctxbatxctxbattxds

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Experimental Study

• Experimental system: Weighing equipment

for heavy vehicle on the circulating lane

• French road network partially equipped

with different measurement stations

(SIREDO, STAL, EPM, …) at some key

points to obtain a reality of the traffic on

national roads and highways

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Experimental study

Measured Variables

speed position acceleration average speed of

the traffic flow

circulating lane

number

weight of the

axle shafts

total weight truck length

truck width truck category overweight lateral position

on the lane

date time truck occupation

rate

road type

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Experimental study

• Estimation of (a, b, c) parameters:

Headway spacing versus

speed (2010, France):

(a) August, (b) June,

(c) September

30 40 50 60 70 80 90 100 110 1200

50

100

150

Speed (km/h)

Hea

dw

ay s

pac

ing

(m

)

20 30 40 50 60 70 80 90 100 110 1200

50

100

150

Speed (km/h)

Hea

dw

ay s

pac

ing

(m

)

-20 0 20 40 60 80 100 120 1400

50

100

150

Speed (km/h)

Hea

dw

ay s

pac

ing

(m

)

(a) (b)

(c)

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EDAS

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Min Safe

speed

in

curve

eH+

Headway spacing

management

Opt

Consum-ption

Decision Unit

vdriver

v

Objects (Crossing…)

vlimit

Curvature

Crossfall

Adhesion vsafe

vopt

Vdist

ddriver

Tdriver

vi

vtarget Slope

A

D

V

I

S

O

R

A

C

T

I

V

E

50 D

R

EDAS

• Legal speed digital map of infrastructure

• Limit speed while entering a curve use of

a curve warning system

• Safe headway spacing

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EDAS

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Conclusion

• Political issues :

– Road managers :

• Safety

• Predictive/Decisive actions

• Infrastructure preservation

– Vehicles flow managers

• Less accidents

• Low energy consumption

– Drivers

• Driving assistance : advisor or active systems in RT

• Eco-driving safely

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Future works

• Performing the measurements with real

tests on given equipped HV

– Accuracy in modelling

• Testing optimization algorithms (safety and

eco) on HV prototype

– First evaluation

• Analysis of the gains in accidentology and

economy

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THANK YOU FOR YOUR ATTENTION !

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