Friction Coefficient Influence on the Engagement Uncertainty in Dry-Clutch AMT

This paper focuses on the control of automotive gearbox based on dry-clutch architecture. Such a system is widely spread as engagement device in Automated Manual Transmissions (AMTs) and Dual-Clutch Transmissions (DCT) to manage the energy flow from the engine to the vehicle wheels. These modern transmissions introduce improvements on shifting quality, fuel consumptions, pollutant emissions at relatively low-cost respect to other automatic transmissions. In particular, the passengers’ comfort and moreover the control action with regard to the clutch engagement, is strongly influenced by the clutch torque characteristic model implemented in the Transmission Control Unit (TCU). Thus, a phenomenological approach to model the torque transmitted by the specific clutch architecture is a critical matter to design robust engagement control strategies. To this aim the controller performance of an actuated dry clutch by taking into account the uncertainty of the frictional phenomena on the clutch torque characteristic has been investigated in this work. The outcomes of this analysis prove the limits related to poor modelling of the influence of operating variables on the clutch torque, even when advanced control algorithms are implemented in the TCU.