Optimal torque coordinating control strategy applied in downshifting process of a novel seamless automatic transmission

摘要

A novel seamless automatic transmission with only a single friction clutch, is focused in this paper. The dynamic model of the automatic transmission's downshifting process, is analyzed to establish the coordinating control strategy on the torque of the engine and the friction clutch. In the optimization, the torque gradient of the friction clutch and the power source are treated as the two control variables. Furthermore, the inequality constraints are applied on the control variables and the state variables. By solving the constrained Bolza problem with the numerical methods, the optimal state variables' trajectory is obtained. Besides, the coordinating control strategy is applied on the simulation model on the Matlab/Simulink platform as well as on bench-test, the results indicate that the characteristic of shifting without driving power interrupt during the downshift process is guaranteed and the dynamic performance is improved.