Optimal Gearshift Strategy in Inertia Phase of Dual-Clutch Transmissions

Shift quality is an important indicator to measure the performance of dual-clutch transmissions (DCT). To obtain optimal driving comfort and reduce the vehicle jerk as much as possible, this paper proposes an integrated gearshift controller to control the engine and the on-coming clutch in inertia phase. First of all, a dynamic model of DCT during gearshift is established. Key factors determining shift quality are analyzed. In order to reduce the vehicle jerk, a reference trajectory of the engine speed and the derivative of the desired torque transferred by the on-coming clutch in inertia phase are programmed respectively. A back-stepping sliding mode controller (BPSMC) is designed to make the actual engine speed track the reference trajectory and an incremental proportional-integrative (PI) controller is designed to make the actual clutch torque to track the desired clutch torque. At the end, simulation and experiment are carried out to validate the effectiveness of the proposed controller. Results show that the tracking error of engine speed is less than 10rad/s and the tracking error of the torque transferred by the on-coming clutch is less than 5Nm. Good tracking performance and driving comfort can be obtained using the proposed controller.