Smooth shift is one of the key issues in automatic power transmission control systems.
However, the torque sensors are too expensive to be used in shift controllers on production
vehicles. In order to provide a basic strategy for smooth shifting by using RPM sensors only and
in order to accomplish the shift within a designated time, this paper studies detailed characteristics
of the smooth shift for clutch-to-clutch shift mechanism. A desired trajectory of slip speed
is proposed for smooth acceleration shift defined in this paper. Also the clutch torque needed
to achieve this trajectory is derived, and it may be used as a open loop shift control law.