The Roles of Front and Rear Cornering Stiffness in Vehicle Directional Dynamics 2016-01-1651

The transfer functions between the variables in linear bicycle models of four wheel automobiles, the input to which is steering angle, were examined. The modal response transfer functions between all of the motion outputs, with the exception of front tire slip angle, were found to be independent of front tire cornering stiffness. It is a role unique to rear cornering stiffness to define the above mentioned transfer functions. This concept was also deductively demonstrated. The concept is true in the frequency domain, therefore, it guarantees that the amplitude ratio between two outputs and the phase difference between two outputs depends only on rear cornering stiffness. However, it is necessary to be cautious, when one applies the concept to phenomena in time domain. For example, the difference in 50 % rise time of two output variables is dependent on front tire cornering stiffness.