Abstract
In this paper, an observer-based torque controller for torque phase and a decoupling controller combined with the internal model control for inertia phase are integrated and applied to up-shift operation of automatic transmission. The control performance is studied through simulation. A mathematical model of the up-shift operation is made by modeling the shift operation as state transition from torque phase to inertia phase. For each state, a mathematical model is made, including the equation of motion of powertrain, clutch actuators, a torque converter, drive shaft stiffness, and vehicle running resistance. During torque phase, the off-going clutch is engaged, and turbine output shaft and planetary gears rotate as one body. Drive shaft torque is generated as a result of drive shaft stiffness. Based on this model, a nonlinear torque observer is used. During inertia phase, input signals, that is, engine torque and on-going clutch pressure, influence drive shaft torque and slip velocity. Interference between these inputs and outputs can be decoupled by a decoupling controller. The decoupling controller is used with the internal model control for the inertia phase. A simulation model of the up-shift operation and the integrated control system are built using MATLAB/Simulink. Simulation study demonstrates performance of the integrated control system. The results show robustness of the integrated control system for uncertain parameters such as valve dynamics and frictional coefficient of clutches.
