Dynamics and control of gearshifts on twin-clutch transmissions

Based on a detailed dynamic model of an automotive powertrain containing a twin-clutch transmission, an integrated powertrain control for gearshifts is developed. The operation of this controller is demonstrated on the basis of simulation results for upshifts, downshifts, and multiple gearshifts taking place within the same half of the transmission. The control algorithm makes use of closed-loop control of clutch slip for a smooth transfer of engine torque with the aim of reproducing the operation of a one-way clutch. Further elements are a closed-loop control of engine speed through a combination of a manipulation of engine controls and clutch pressure. In addition, it is demonstrated that the control of transmission output torque during gearshifts can add robustness to the control and provides a means to manipulate directly the gearshift character. Finally, the dynamic effects of gear preselection through conventional hydraulically actuated cone-type synchronizers on the overall shift quality are discussed.