Development of High Force Electromechanical Linear Actuator for Shift-By-Wire Automated Manual Transmissions

Electromechanical actuation systems are being considered as an alternative to hydraulic systems for controlling clutches and gearshifts in transmissions, since they offer the potential for improved efficiency, better packaging and a reduction in component count. A high-force direct-drive linear electromechanical actuator has been developed which acts directly on the shift rails of either an Automated Manual Transmission (AMT) or a Dual Clutch Transmission (DCT) to facilitate gear selection and provide shift-by-wire functionality. This actuation scheme offers a number of advantages over electric motor and gearbox actuator designs, including simplified construction; the elimination of mechanical gearing, which reduces mechanical hysteresis, backlash and compliance; a low component count, which results in improved robustness; a better dynamic response and the potential for zero ‘off-state’ power consumption. The actuator is controlled using a PD control scheme and MOSFET H-bridge power electronic drive.