Optimal control of gear shift operations in automatic transmissions

Abstract

An optimal control approach for gear shift operations in automatic transmissions is proposed in this paper. Starting from a verified model of a typical power train with an automatic transmission a performance measure for evaluating the gear shift process in terms of passengers comfort and control expenditure is developed. The gear shift operation is stated as a multistage decision process by making use of the dynamic programming method. Thereby, the synchronization of the gear box is formulated as a constraint at the end of the process. A control law is derived analytically in an explicit form by minimizing the performance measure over each process stage. Simulation results show a significant improvement in terms of gear shift comfort by different driving load cases. Furthermore, the shift time and the frictional losses in the shift elements can be reduced by applying the proposed control.