Robust control of synchromesh friction in an electric vehicle´s clutchless automated manual transmission

The aim of this study is to control the synchronizer operation in an automated manual transmission (AMT) in which the clutch is eliminated from the driveline to reduce the power losses. The goal of controlling the synchronization phase is to increase the lifetime of the synchronizer by establishing control over the frictional behaviour of such tribological system. The robust control approach starts by introducing the lubricated friction operating states and follows by modelling the dynamic system as well as the primary uncertainties affecting the synchronization phase. Considering the system uncertainties, a robust H_∞ multivariable controller is designed and the closed-loop performance is assessed by considering the noise and disturbance effects. The advantages of the proposed robust controller is discussed and compared with the performance of a PID controller which operates in the same closed-loop control configuration. The case study here is a synchronizer which is part of a 2-speed AMT designed for efficient gear shifting in an electric vehicle, with the purpose of improving the energy efficiency and enhancing the drive motor performance.