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Gear Shifting Behavior Model for Ecodriving Simulations Based on Experimental Data

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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.

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Gear Shifting Behavior Model for Ecodriving Simulations Based on Experimental Data

  1. 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
  2. 2. Présentation Ifsttar 04012011 ECODRIVING: A TECHNICAL POINT OF VIEW Part 1
  3. 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. 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. 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. 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
  7. 7. Présentation Ifsttar 04012011 Ecodriving definition: weights
  8. 8. Présentation Ifsttar 04012011 INTRODUCTION Part 2
  9. 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. 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. 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. 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
  13. 13. Présentation Ifsttar 04012011 DRIVER BEHAVIOR ANALYSIS Part 3
  14. 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. 15. Présentation Ifsttar 04012011 Results: typical pattern Shift up - Normal driving Shift up - Ecodriving Shift down - Normal driving Shift down - Ecodriving
  16. 16. Présentation Ifsttar 04012011 Results: All trips Shift up - Normal driving Shift up - Ecodriving Shift down - Normal driving Shift down - Ecodriving
  17. 17. Présentation Ifsttar 04012011 Results: Question of neutral Shift up - Normal driving Shift up - Ecodriving Shift down - Normal driving Shift down - Ecodriving
  18. 18. Présentation Ifsttar 04012011 Results: No change Shift up - Normal driving Shift up - Ecodriving Shift down - Normal driving Shift down - Ecodriving
  19. 19. Présentation Ifsttar 04012011 Results: Engine speed distribution • Distributions for second and fifth gears are similar • Distributions for forth and third gears are similar
  20. 20. Présentation Ifsttar 04012011 MODELLING Part 4
  21. 21. 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
  22. 22. 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
  23. 23. Présentation Ifsttar 04012011 VALIDATION Part 5
  24. 24. Présentation Ifsttar 04012011 Validation
  25. 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
  26. 26. Présentation Ifsttar 04012011 CONCLUSIONS Part 6
  27. 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)

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