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Look Ahead Control - Consequences of a Non-Linear Fuel Map on Truck Fuel Consumption
Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology. (Scania CV AB, Södertälje Sweden)
Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
2008 (English)In: The 17th IFAC World Congress, 2008Conference paper, Published paper (Other academic)
Abstract [en]

Consequences of non-linearities in specific fuel consumption, sfc, of a heavy truck combustion engine are studied with focus on so small road gradients that constant speed is optimal if the engine torque has an affine relation to fueling. A quasi-static analysis gives valuable insights into the intrinsic properties of minimization of fuel consumption. Two objective functions are shown to give different optimal velocity trajectories on a constant road gradient, when the non-linearity in sfc is significant, a notation which is quantified. For a significant non-linearity, when a constraint is set to keep a final time, switching between two characteristic speeds is optimal. Alternatively, if consumed time, in addition to fuel consumption, is part of the objective function, then keeping to one constant speed is optimal also for significant non-linearities. However, the different optimal solutions still show similarities, since for a certain significant non-linearity a specific speed range determined by the characteristic velocities is shown to be unobtainable for both optimality criteria. Similar results are obtained for a full dynamic model including a realistic fuel map and other realistic constraints.

Place, publisher, year, edition, pages
2008.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-18188OAI: oai:DiVA.org:liu-18188DiVA: diva2:216638
Conference
The 17th IFAC World Congress
Note

This article is an extended version of (Ivarsson et al., 2008), Optimal Speed on Small Gradients – Consequences of a Non-Linear Fuel Map, presented at the IFAC World Congress 2008.

Available from: 2009-05-11 Created: 2009-05-11 Last updated: 2013-02-27
In thesis
1. Fuel Optimal Powertrain Control for Heavy Trucks Utilizing Look Ahead
Open this publication in new window or tab >>Fuel Optimal Powertrain Control for Heavy Trucks Utilizing Look Ahead
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The road topography in highways affects the powertrain control of a heavy truck substantially since the engine power is low in relation to the vehicle weight. In large road gradients constant speed is not possible to keep, which would have been beneficial otherwise, and in some uphills shifting gears becomes inevitable. If information about the road ahead, i.e. look ahead information, is available, then the powertrain can be controlled in a more fuel efficient way. Trial runs are performed, where the velocity trajectory that minimizes energy consumption, is calculated and communicated in real time as set points to the conventional cruise control. This look ahead control gives significant fuel consumption reductions compared to a standard cruise control, while keeping to the same mean speed. The results are the inspiration to further studies in how powertrain control can benefit from look ahead information. An engine with a non-linear fuel map is studied to understand its impact on fuel optimal speed. It is shown that for a significant fuel map non-linearity, quantified by a threshold value, constant speed in small road gradients is no longer optimal. Further, an automated manual transmission (AMT) optimal gear control is studied. It is shown that the reduced propulsion of a typical AMT gear-shifting process must be considered when choosing when to shift gears. Thus, additional reductions of fuel consumption are obtained with a look ahead control based on knowledge of engine and transmission characteristics.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 14 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1400
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-18077 (URN)978-91-7393-637-8 (ISBN)
Presentation
2009-04-28, Glashuset, B-Huset, Campus Valla, Linköpings universitet, Linköping, 10:00 (Swedish)
Opponent
Supervisors
Available from: 2009-05-11 Created: 2009-05-05 Last updated: 2009-06-12Bibliographically approved

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Ivarsson, MariaÅslund, JanNielsen, Lars

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