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Abstract

The objective of this research was to examine the effects of low-stiffness-resilient-shaft (LSRS) maximum deflection angle on the response of a vehicle equipped with Semi Active Steering System (SAS) during the failure of Steer-by-wire (SBW). Modelling of LSRS stiffness that considers deflection angle was proposed and incorporated to the 3-DOF bicycle model of the vehicle dynamic. Simulations were performed on MATLAB/SIMULINK for several vehicle longitudinal speeds and the LSRS maximum deflection angles by applying a standard step steer input. Simulation results showed that vehicle responses were considered safe from roll over problem during the specified cornering maneuver since the lateral acceleration and yaw velocity values of the SAS system were always lower than the ones of the conventional systems. The turning radius was found to increase as the maximum deflection angle increased. However, the turning radius became constant after a certain maximum deflection angle was used. The maximum deflection angle of LSRS to be as low as possible, between 10o to 30 o was suggested for keeping a consistent vehicle’s drivability.