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Impacts of AMT Gear-Shifting on Fuel Optimal Look Ahead Control
Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology. (Scania CV AB, Södertälje Sweden)
Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
2009 (English)Report (Other academic)
Abstract [en]

A fuel optimal gear shift control has been studied, when look ahead information is available, and the impact of the automated manual transmission (AMT) gear-shifting process is analayzed. For a standard discrete heavy truck transmission, answers are found on when to shift gears, prior to or when in an uphill slope. The gear-shifting process of a standard AMT is modeled, not considering the comfort details, in order to capture the fuel and time aspects of the gear shift. A numerical optimization is performed by dynamic programming, minimizing fuel consumption and time by controlling fuel injection and gear. Since a standard AMT does not have look ahead information, it sometimes gears down unnecessarily and thus gives a significantly higher fuel consumption compared to the optimal control. However, if gearing down is inevitable, the AMT gear-shifting strategy, based on engine thresholds, is a well-functioning gear control so that the optimal control only gives marginal additional savings. To attain the possible fuel reductions it is shown that the reduced propulsion of an AMT gear-shifting process, and the resulting vehicle retardation, must be considered. The point of shifting gears must be chosen to ensure an adequate engine speed in order to get a sufficient engine power after the gear shift, even as the truck is decelerated during gear shift.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2009. , 14 p.
Series
LiTH-ISY-R, ISSN 1400-3902 ; 2883
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-18189ISRN: LITH-ISY-R-2883DOI: 10.4271/2010-01-0370OAI: oai:DiVA.org:liu-18189DiVA: diva2:216643
Available from: 2009-05-11 Created: 2009-05-11 Last updated: 2014-09-24Bibliographically approved
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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