Smooth shift control of an automatic transmission for heavy-duty vehicles

In this paper, a robust shift control strategy of a heavy duty vehicle powertrain system is investigated for enhancing shift quality. To analyse the shift transient phenomena, the dynamic models for various powertrain components, such as engine, torque converter, transmission and drivetrain, are developed. Three different robust adaptive control laws are derived for the different process control that reduces the output torque during the gear shifts. In deriving the control laws, both the engine and automatic transmission dynamics have been included. In order to overcome the challenge of the relevant variables characterizing the performance of the powertrain is not measurable because of sensor cost and reliability considerations. The integrated controller proposed uses only angular velocity signals, such as engine speed, turbine speed and output speed, which are inexpensive to measure and easy to implement. Finally, the designed control strategy is tested on a heavy-duty vehicle equipped with automatic transmission. Results from the experimental studies show that the proposed control strategy can effectively reduce shift shock and smooth the gear shift.