Advance techniques to optimize Variable Gear Ratio steering for high Centre of Gravity vehicles.

High center of gravity (CG) and moderate Wheel track vehicles such compact SUVs has comparatively low static stability factor (SSF). Making them unstable and highly susceptible for rollover. On the top of that, to enhance the ease of maneuverability in densely populated areas, it is required to have a minimal turning circle diameter (TCD). To do so, variable gear ratio (VGR) steering stands superior to conventional constant gear ratio (CGR) steering, benefiting in both improved roll stability and agility to manoeuvre in compact spaces. To fine-tune VGR steering for specific vehicle requirements, Driver-in-the-Loop (DIL) simulation is used. This method allows for precise adjustments based on real-world driving conditions, ensuring the VGR steering C-factor curve is optimized for ideal vehicle handling performance in on-center, off-center, and transition regions of the steering wheel angle (SWA). Metrics such as SWA gradient at different lateral accelerations and C-factor transitions for various SWA are evaluated in the DIL simulator to maintain a natural steering feel. Furthermore, DIL helps assess the realistic cycloidal behavior of the curve, manufacturing asymmetries, and their effects on driving performance.