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Driveline Modeling and Principles for Speed Control and Gear-Shift Control
Linköping University, LiU-TEK-LIC-1996:29, Thesis No. 564,
ISBN 91-7871-744-2, ISSN 0280-7971. A vehicular driveline consists of engine, clutch, transmission,
shafts, and wheels, which are controlled by a driveline management
system. Experiments and modeling using a heavy truck show that there are
significant torsional resonances in the driveline. A linear model with
a drive shaft flexibility is able to sufficiently explain the measured
engine speed and wheel speed. Engine control for automatic gear shifting is an approach at the
leading edge of technology. A critical step is the controlling of the
engine such that the transmission transfers zero torque, whereafter
neutral gear can be engaged. Driveline oscillations is a limiting
factor in this system. A model of the transmission torque is developed
and a state-feedback controller is used to drive this torque to zero.
The result is a possibility to optimize the time needed for a gear
shift. Furthermore, neutral gear can successfully be engaged also
when facing load disturbances and initial driveline oscillations.
Traditionally in diesel trucks, the engine speed is controlled by a
system called RQV. This system has the desired property of a load
dependent stationary error, and the undesired property of vehicle
shuffle following a change in pedal position. A model based
state-feedback controller is derived that actively reduces wheel speed
oscillations. The performance and driveability is significantly
improved, while maintaining the desired load characteristics for RQV
control.
In conclusion, the proposed strategies improve performance and
driveability in both speed control and gear-shift control.
Magnus Pettersson
1996
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