Post on 11-Jan-2017
Présentation Ifsttar 04012011
EWGT2012
Gear Shifting Behavior Model for Ecodriving
Simulations Based on Experimental Data
Olivier Orfila, Guillaume Saint Pierre, Cindie Andrieu12/09/2012
Présentation Ifsttar 04012011
ECODRIVING: A TECHNICAL
POINT OF VIEW
Part 1
Présentation Ifsttar 04012011
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)
Présentation Ifsttar 04012011
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
Présentation Ifsttar 04012011
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
Présentation Ifsttar 04012011
Ecodriving definition: proposal
– Ecodriving is, at every moment, a multicriteria
optimisation (energy consumption, safety, travel time,
comfort,…) of each driving task
InfraVehicle
Other drivers
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Ecodriving definition: weights
Présentation Ifsttar 04012011
INTRODUCTION
Part 2
Présentation Ifsttar 04012011
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
Présentation Ifsttar 04012011
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.
Présentation Ifsttar 04012011
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.
Présentation Ifsttar 04012011
Methodology
• 3 steps methodology:
– Analysis of driver behaviors in normal and ecodriving
throughout experiments
– Gear behavior model development
– Gear behavior model validation
Présentation Ifsttar 04012011
DRIVER BEHAVIOR ANALYSIS
Part 3
Présentation Ifsttar 04012011
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
Présentation Ifsttar 04012011
Results: typical pattern
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
Présentation Ifsttar 04012011
Results: All trips
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
Présentation Ifsttar 04012011
Results: Question of neutral
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
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Results: No change
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
Présentation Ifsttar 04012011
Results: Engine speed distribution
• Distributions for
second and fifth gears
are similar
• Distributions for forth
and third gears are
similar
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MODELLING
Part 4
Présentation Ifsttar 04012011
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
Présentation Ifsttar 04012011
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
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VALIDATION
Part 5
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Validation
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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
Présentation Ifsttar 04012011
CONCLUSIONS
Part 6
Présentation Ifsttar 04012011
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)