Observer-based feedback control during torque phase of clutch-to-clutch shift process

In order to improve the shift quality of Automatic Transmissions (ATs) adopting clutch-to-clutch shift technology, a feedback control strategy is proposed for the torque phase of shift process. With the estimated clutch torque, the off-going clutch is disengaged at the moment when transmitted torque is approaching zero, which contributes to the reduction of shift shock and prevention of clutch tie-up. The proposed control strategy is tested on a complete powertrain simulation model. It is verified that the system is robust to the variations of driving conditions, such as vehicle mass and road grade, etc.