Adaptive strategy for the automatic transmission shifting improvement

Shift quality and shift time of the automatic transmission is required to be consistent in mass production and with mileage accumulation. In order to compensate for the influence of build-to-build variations and life-cycle variations on shifting process, there should be an adaptive control in the software in addition to the base control of the shifting process. The adaptive control can adjust control parameters to compensate for the variations of physical characteristics. Thus shift quality will be improved step by step through the learning process. Some adaptive control methods are proposed in this paper. In torque phase, the adaptive strategy tries to keep the clutch slip in a small range to avoid clutch tie-up and engine flare. In inertia phase, the adaptive strategy tries to keep the time of the speed synchronization process in a proper range to avoid a long shifting time or a shifting impact. Vehicle tests verified that this adaptive control strategy can effectively eliminate the engine flare, and the clutch tie-up in power on up shift and to get a better shift quality and proper shift time.