Ecodriving is known as a way to quickly and efficiently reduce fuel consumption for the concerned ecodriven vehicle. However, the impact of ecodriving on a whole road network at a large scale is unknown. In order to perform studies in a micro traffic simulation software, a fuel consumption model coupled to a gear behavior model are required.
This study presents a gear shifting behavior model able to represent as well the variability of drivers as the difference between ecodriving and normal driving. This work, based on the evaluation of the real driver behaviors during 42 trips, has been partially validated with a result of 60% of time spend in the correct gear.
Future works will be concentrated on a detailed validation of this model and on its implementation with a fuel consumption model.
Gear Shifting Behavior Model for Ecodriving Simulations Based on Experimental Data
1. Présentation Ifsttar 04012011
EWGT2012
Gear Shifting Behavior Model for Ecodriving
Simulations Based on Experimental Data
Olivier Orfila, Guillaume Saint Pierre, Cindie Andrieu
12/09/2012
3. 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)
4. 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
5. 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
6. 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
9. 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
10. 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.
11. 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.
12. 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
14. 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
15. Présentation Ifsttar 04012011
Results: typical pattern
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
17. Présentation Ifsttar 04012011
Results: Question of neutral
Shift up -
Normal driving
Shift up -
Ecodriving
Shift down -
Normal driving
Shift down -
Ecodriving
19. Présentation Ifsttar 04012011
Results: Engine speed distribution
• Distributions for
second and fifth gears
are similar
• Distributions for forth
and third gears are
similar
25. Présentation Ifsttar 04012011
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
27. 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)