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Abstract



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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