Fuel Optimal Powertrain Control for Heavy Trucks Utilizing Look Ahead
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.
Maria Ivarsson
2009
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Last updated: 2021-11-10
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