Robust clutch slip controller design for automatic transmission

To improve the drivability of vehicles with automatic transmissions, a closed-loop turbine speed controller for the inertia phase of the gear shift is designed. Since the system must be robust to the changes in the operating conditions and any deterioration in the automatic transmission fluid (ATF) and the friction material, a robust approach should be used to obtain acceptable performance, even for the worst case. Moreover, as it is known that the change of turbine torque in the inertia phase greatly affects the turbine speed tracking performance, it is important and necessary to suppress the tracking error from the influence of turbine torque. In this paper, based on a linearized model derived from the dynamics of a vehicle powertrain, a two-degree-of-freedom (2DOF) robust proportional–integral–differential (PID) controller is discussed, considering the uncertainties of the proposed model. The estimated turbine torque is used in the feedforward channel to enhance the disturbance rejection performance, while the feedback channel ensures that the system is quadratically stable under various operating conditions and friction characteristics. In this study, MATLAB is utilized as the programming environment, and the powertrain system is analysed in the control-oriented sense. The proposed controller is validated by the simulation of 1–2 upshift.