TABLE OF CONTENTS An important basis for design of driveline management is to understand the dynamic behavior of the driveline before and after going from a gear to neutral. This requires additional modeling of the driveline since it is separated in two parts when in neutral. Such a decoupled model is the topic of this section, together with its use for analysis of possible oscillation patterns of the decoupled driveline.
A decoupled model has several applications. It is the basis for a diagnosis system of gear-shift quality. The analysis cast light on the sometimes, at first sight, surprising oscillations that occur in an uncontrolled driveline. It is also an indication for the value of feedback control.
First, a series of gear-shifts with a stationary driveline are performed without using driveline torque control. This means that a speed controller controls the engine speed to a desired level, and when the driveline speeds have reached stationary levels, engagement of neutral gear is commanded. Figure 7.21 shows two of these trials where the engine speed is 1400 RPM and 2100 RPM respectively, on a flat road with gear 1. The behavior of the engine speed, the transmission speed, and the wheel speed is shown in the figure. At t = 14 s, a shift to neutral is commanded. A gear shift is performed by using a gear lever actuator driven by air pressure. A delay-time from commanded gear shift to activated gear-lever movement is seen in...
