1. Introduction
In spite of the lower efficiency and higher cost,
automatic power transmission system has gained
widespread use in most passenger vehicles due to
its easy drive-ability, as well as torque amplifying
and the torsional damping characteristics of torque
converter. In shift control, two important
issues are shift point decision and shift quality
control (Jeong, 1993). The former considers the
issue of under what operating condition the shift
should be conducted for greater fuel economy.
The latter is concerned with how to accomplish
gear ratio changes smoothly for passenger comfort.
This paper concentrates on the shift quality
control.
A conventional automatic transmission uses
planetary gear sets to provide different speed
ranges and over-running sprags to give smooth