Simulation-based evaluation of speed-adaptive steering ratios in four-wheel steer-by-wire vehicles

Vehicle handling requires a careful balance between agility at low speeds and stability at high speeds, a trade-off that traditional fixed-link steering systems struggle to address. Steer-by-wire (SBW) technology removes the mechanical connection between the steering wheel and wheels, enabling realtime, independent adaptation of the steering ratio at both front and rear axles. This work presents a preliminary simulation-based evaluation of a speedadaptive variable steering ratio strategy applied to both axles, aimed at improving handling under diverse conditions. Validation was performed through offline ISO standardised open-loop manoeuvres and driver-in-the-loop (DiL) simulations, providing early subjective insights. While results indicate potential improvements in manoeuvrability and stability, the current validation underscores the need for further research and broader experimental evaluation to confirm these findings. This study lays the groundwork for future investigations into optimising speedadaptive steering in Four-Wheel SBW systems.