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Abstract |
Impact of AMT Gear-Shifting on Fuel Optimal Look Ahead Control
For a fuel optimal gear shift control, when look ahead information
is available, the impact of the automated manual transmission (AMT)
gear-shifting process is analyzed. 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 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 well-functioning so that the optimal control
only gives marginal additional savings. To attain the possible fuel
reductions it is shown that the occasion of shifting gear must be
chosen to ensure an adequate engine speed in order to get a sufficient
engine power after the gear shift. The reduced propulsion of an AMT
gear-shifting process, and the resulting vehicle retardation, must be
considered.
Maria Ivarsson, Jan Åslund and Lars Nielsen
SAE Technical Paper Series, 2010
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