7.6: Anti-Jerking Control for Passenger Cars

7.6 Anti-Jerking Control for Passenger Cars

In recent years the engine torque of Diesel engines has been increasing rapidly also for personal cars. Thereby, like for trucks, problems for driveability and comfort arise, and also here the problem with the high engine torque is torsion of the driveline. Due to the transmission ratio of the final drive the torsion primarily occurs at the drive shaft, and it causes power train oscillations combined with jerking of the vehicle. Figure 7.71 shows the behavior of a test car during so-called tip in, an abrupt step on the throttle followed by a high torque gradient, and tip out, the reverse maneuver and as can be seen the engine speed and wheel speed clearly show oscillations. The oscillations of the engine speed are partly absorbed by the engine mounting whereas the oscillations of the wheel speed correspond to the performance of the car and are therefore directly felt by the passengers.

Figure 7.71: Engine torque and engine speed for tip in and tip out maneuvers.

To avoid these oscillations and to increase the comfort of the passengers, damped driveline control like in Section 7.4 is necessary. This is often called Anti-Jerking Control. Historically, the construction of the power train along with the drive shaft was optimized but the results were not satisfying [39]. Another possible solution would be to avoid high torque gradients, but however, the disadvantage would be restrictions in response.

As an additional illustration of the model-based approach...