Gear Shifting Behavior Model for Ecodriving Simulations Based on Experimental Data

Présentation Ifsttar 04012011

EWGT2012

Gear Shifting Behavior Model for Ecodriving

Simulations Based on Experimental Data

Olivier Orfila, Guillaume Saint Pierre, Cindie Andrieu12/09/2012


ECODRIVING: A TECHNICAL

POINT OF VIEW

Part 1


Why studying ecodriving: The role of

passenger cars ?

• Fuel consumption US 2004 (IEA)

• In France, passenger cars represents 55% of greenhouse gases

emissions (source: ministry of sustainable development)


And the role of vehicle, infrastructure

and driver?

Driver:•Desired acceleration

•Desired speed

•Engine speed,… =

ecodriving

Vehicle:•Mass

•Engine

•Tires,…

Infrastructure:•Geometry

•Pavement texture

•ITS


Ecodriving definition

« eco-driving primarily consists of a variety of driving techniques

that save fuel and lower emissions. do not drive too fast; do not

accelerate too quickly; shift gears sooner; maintain steady speeds; and keep the

vehicle in good maintenance; anticipate traffic flow when accelerating and slow

down smoothly for stopped traffic. » M. Barth, K. Boriboonsomsin, 2009. Energy

and emissions impacts of a freeway-based dynamic eco-driving system

« Eco-driving should be distinguished from hypermiling. Clearly

hypermiling trades off safety for fuel economy, while with eco-

driving there is no tradeoff. » J. N. Barkenbus, 2010. Eco-driving: An

overlooked climate change initiative

« Eco-driving aims at cruising or safely following a car in the

traffic stream in such a way that the fuel consumption in long run

is minimum. » M.A.S. Kamal, M. Mukai, J. Murata and T. Kawabe, 2010. On

board eco-driving system for varying road-traffic environments using model

predictive control


Ecodriving definition: proposal

– Ecodriving is, at every moment, a multicriteria

optimisation (energy consumption, safety, travel time,

comfort,…) of each driving task

InfraVehicle

Other drivers


Ecodriving definition: weights


INTRODUCTION

Part 2


Research questions and objectives

• What would be the impact of promoting ecodriving ?

– Partial answer: can be modelled in micro traffic

simulations

• How can the impact of gear shift behavior be assessed ?

– Need of a gear shifting behavior model


Previous works 1/2

• Studies on the driver behavior and his efforts applied on

the gearbox. For instance, a study from Harley et al.

reported driver's errors when manipulating the gear shift

lever

• Studies on the optimization of gear shifting operations

(Haj-Fraj and Pfeiffer, 2001), where an optimal control of

shifting operation is proposed.


Previous works 2/2

• Studies on gear shift indicators. A report from AEA

Energy and Environment analyzed the impact of this kind

of system and concluded on the efficiency of gear shift

indicators.

• Studies on gear shift modeling. van Arem et al. proposed

a simple model where upper and lower limits for engine

speed trigger the gear shift action. However, the

variability for a specific driver and between drivers has

not been modeled.


Methodology

• 3 steps methodology:

– Analysis of driver behaviors in normal and ecodriving

throughout experiments

– Gear behavior model development

– Gear behavior model validation


DRIVER BEHAVIOR ANALYSIS

Part 3


Description of experiments

• 20 drivers drive two runs on a 14km test track in a

naturalistic driving way

– normal driving

– ecodriving (ecodriving defined as following the

ecodriving rules)

• Vehicle and engine speed have been recorded and used

to compute the engaged gear


Results: typical pattern

Shift up -

Normal driving

Shift up -

Ecodriving

Shift down -

Normal driving

Shift down -

Ecodriving


Results: All trips

Shift up -

Normal driving

Shift up -

Ecodriving

Shift down -

Normal driving

Shift down -

Ecodriving


Results: Question of neutral

Shift up -

Normal driving

Shift up -

Ecodriving

Shift down -

Normal driving

Shift down -

Ecodriving


Results: No change

Shift up -

Normal driving

Shift up -

Ecodriving

Shift down -

Normal driving

Shift down -

Ecodriving


Results: Engine speed distribution

• Distributions for

second and fifth gears

are similar

• Distributions for forth

and third gears are

similar


MODELLING

Part 4


Modelling principle: Shift-up

δ

ωmax2

• Only 2 parameters:

– δ=(ωmax2- ωmax0)/2

– ωmax2

• Computation of max

engine speed for

each gear:

– ωmax1= ωmax2-δ

– ωmax4= ωmax2-δ


Modelling principle: Shift-down

• Driver’s independent engine speed trigerring shift down

action

Destination gear Engine speed (rpm)

4 1180

3 1130

2 1040

1 960

Neutral 940


VALIDATION

Part 5


Validation


Validation: Accuracy distribution

• Accuracy defined as

the time rate spent in

the good gear

• 60% mean accuracy

• From 40 to nearly

80% of accuracy

• Constant model gives

20% mean accuracy


CONCLUSIONS

Part 6


Conclusions

• Driver behavior in terms of gear shift has been assessed

with experimental data.

• A simple model has been proposed and validated.

• Perspectives:

– This model requires to be further validated with more

drivers and different roads

– This model could be completed taking into account

the road slope information

– This model will be applied for real-time estimation of

fuel use on smartphone applications (ecoDriver

project)

Gear Shifting Behavior Model for Ecodriving Simulations Based on Experimental Data

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