A Study on the controllability of Vehicle Steer-by-Wire systems for Safety Architecture Development

This paper describes the controllability investigation of vehicle Steer-by-Wire(SbW) system for the safety architecture development. In currently used electric steering systems failure, safe state will be the intended loss of assist(LOA) for preventing unintended self-steer or inappropriate vehicle lateral control and the related studies have been conducted so far. However, in a steer by wire system, there can be no mechanical coupling between the steering wheel and the steering mechanism. Consisting SbW system, Steering Feedback Actuator(SFA) and Road Wheel Actuator(RWA) shall be addressed different safe states separately. Even though the loss of assist occurs on SFA, RWA can be in the vehicle lateral control state by using the steering angle signal. The paper focuses on the controllability of the SFA failure. The methodological approach is composed of questionnaire jury ratings, driving behaviors and physiological measures. The results shows the possible options for the single fault tolerant safety architecture of SbW systems.