7.3 Driveline Control

There are two types of variables that are of special interest in driveline control:

• (rotational) velocities

• torques

Since the parts of a vehicular driveline (engine, clutch, transmission, shafts, and wheels) are elastic, velocities and torques differ along the driveline. It also means that mechanical resonances may occur. The handling of such resonances is basic for functionality and driveability, but is also important for reducing mechanical stress and noise. New driveline-management applications and high-powered engines increase the need for strategies for how to apply engine torque in an optimal way.

Two important applications for driveline control are

• driveline speed control

• driveline control for gear shifting

These two applications will be treated in the following sections. The first application is important to handle wheel-speed oscillations following from a change in accelerator pedal position or from impulses from towed trailers and road roughness, known as vehicle shuffle.

The second application, driveline control for gear shifting, is used to implement automatic gear shifting. In todays traffic it is desired to have an automatic gear shifting system on heavy trucks. One approach at the leading edge of technology is gear shifting by engine control [91]. With this approach, disengaging the clutch is replaced by controlling the engine to a state where the transmission transfers zero torque, and by that realizing a virtual clutch. After neutral gear is engaged, the engine speed is controlled to a speed such that the new gear can be engaged. The gear shifting system uses a manual transmission...