Braking and steering performance analysis of a road vehicle with active independent front steering

Active front steering (AFS) systems help achieve target handling performance through simultaneous applications of steering corrections to both the wheels, but may exhibit limited performance during high-speed manoeuvres. This study explores the effectiveness of an active independent front steering (AIFS) system under application of braking to demonstrate that it could not only overcome the limitation of the AFS but also provide sufficient adhesion reserve for generating longitudinal forces. A simple AIFS controller is synthesised using the yaw rate feedback and the tyres' saturation limits. The simulation results are obtained under a wide range of braking-in-turn manoeuvres in different road conditions. Comparisons of the results with those obtained with the conventional AFS suggested greater effectiveness of the AIFS under high-speed manoeuvres. A parametric study is subsequently conducted to study the robustness of the AIFS performance. The results demonstrated enhanced braking-in-turn performance of the AIFS under conditions where the understeer handling characteristic exists.