Clutch slip control of automatic transmissions: A nonlinear feedforward-feedback design

To improve the shift quality of vehicle with clutch-to-clutch gear shifts, a nonlinear controller based on flatness is proposed for the clutch slip control during the inertia phase. A nonlinear feedforward control is designed in consideration of the system nonlinearities, and a linear feedback control is given to accommodate the model errors and the disturbances. The proposed control scheme has small computational demand and the complex nonlinear characteristics of powertrain system appear in their original form of lookup tables. Finally, the designed controller is tested on an AMESim powertrain simulation model, which contains a time-variant model of clutch actuators.