Steering On-Center Feel and Yaw Response Enhancement through Optimization of System Level Characteristics

To export India based SUVs to European markets, change in steering position is required to suit vehicle driving condition. Ideally, RHD and LHD variants of a same vehicle should have similar level of ride and handling performance parameters. However, due to various packaging constraints and regulations, there is a possibility of minor change in hardpoints of steering or suspension system which may lead to different behaviour in terms of body roll and steering response. While cornering or double lane change maneuvers, difference in steering phase angles or steering stiffness or suspension hardpoints results in different roll behaviour as well understeer characteristics of the vehicle. The present study shows key parameters and optimization methodology to maintain same level of ride and handling performance in both RHD and LHD variants. Objective measurements and, physical kinematics and compliance tests were carried out with various configurations of RHD and LHD variants to understand the roll gradient, understeer characteristics as well as steering on-center response and deadbands. Multi Body Dynamics models were developed to investigate and carry out sensitivity analysis to understand the impacts of different suspension and steering to achieve same level of performance in both the variants. The results showed that with minimal changes in hardpoints, tuning of suspension and steering components could lead to optimization of R&H metrics in RHD and LHD variants. As a result, methodology was developed for identification of variation in steering performance through subjective and objective correlation, based on which optimization of system level characteristic was carried out to enhance steering and handling performance.