Control strategy for the torque phase in up-shift process of an electrically-controlled automatic transmission

A model for power shift system is built for dynamically analyzing the torque phase in up shift process of automatic transmission. Aiming at the problem of shift shock with traditional control strategy, an ideal control objective for torque phase is proposed based on the requirements of improving shift smoothness. A varying torque changing rate is adopted to replace the constant one in traditional control strategy and an open-loop adaptive control strategy is formulated. A model reference adaptive controller is designed to reduce the disturbance caused by the changes of temperature and loading, and an adaptive correction is made on the parameters of open-loop control with the changing rate of the rotation speed difference in off-going clutch as feedback variable. The results of real vehicle test verify that the control strategy proposed can effectively reduce the shift shock in automatic transmission.