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In this paper, a new gear preselect strategy of wet dual clutch transmission (DCT) is proposed by delaying the gear preselect to the time near the power shift time in order to create a seamless gear preselect. Software in the loop (SiL) method is used to investigate the proposed strategy. High fidelity 13 degree of freedom lumped inertia drivetrain models, i.e., synchronizer model and electro hydraulic model, are constructed and validated using laboratory test data. A closed loop control for electro hydraulic system is developed to control the clutch and synchronizer considering the optimum synchronizer trigger time. Furthermore, the model used in this study is constructed considering the valve spool dynamic in electro hydraulic system and the sleeve dynamic including axial drag force in synchronizer system. The genetic algorithm has been used to obtain the optimum trigger time which is close to the power shift time to sustain uninterrupted torque during gear shifting.

Powertrain control strategies achieving high performance and better shift control depend critically on the available measurements taken directly from the sensors. For Dual Clutch Transmission (DCT), the clutch friction forces are very important to improve the shift quality. So the estimations are needed to be able to set up the shift control on the powertrain system. For better shift comfort, accurate information for the dual clutch transmission should be available to control the clutch pressure. Furthermore, torque sensors for rotating shafts cannot be used on production vehicles since they are expensive and enduring in the environment of the automotive system. This paper presents an Improved Proportional Integral (IPI) observer for estimation of the unknown forces acting on the clutch during shift processes as well as the non measured states. The estimated unknown forces can be used for the closed-loop control of the dual clutch transmission for better shift quality.