Patent ID: 6976555
Filing Date: 2005-12-20
Classification: B62D

Abstract:
1. A motor vehicle steering system selectively operable in a steer-by-wire mode, an electronic power assist (EPAS) mode, and a manual mode, the steering system comprising: a road wheel actuator system including a road wheel actuator adapted for directing an at least one road wheel in accordance with a steering value; a driver interface system including a reaction torque generator, the driver interface system coupled to the road wheel actuators system, the driver interface system adapted to determine the steering value, and further adapted to communicate the steering value to the road wheel actuator system; a clutch mechanism selectively coupling the driver interface system and the road wheel actuator system; a flexible steering member coupled to the clutch mechanism and the road wheel actuator; a controller adapted to determine one of the steer-by-wire mode, the EPAS mode, or the manual mode, the controller coupled to the road wheel actuator system, the driver interface system, and the clutch mechanism; a battery to provide electrical current to the driver interface system and the road wheel actuator system, and further comprising a battery current sensor coupled to the controller, the battery current sensor sensitive to fluctuations in battery current; wherein in response to a driver interface system malfunction, the controller is adapted to deactivate the reaction torque generator, and further wherein the controller controls the road wheel actuator to provide electronic steering power assist; whereby in the steer-by-wire mode the controller maintains the clutch mechanism in a disengaged state and the controller operates the driver interface system and the road wheel actuator system such that the motor vehicle is electronically steerable; whereby in the EPAS mode the controller causes the clutch mechanism to engage and selectively causes one of the road wheel actuator system or the driver interface system to provide electronic power assist steering; and whereby in the manual mode the controller causes the clutch mechanism to engage such that the motor vehicle is mechanically steerable.