The Three Suspension Roll Centers and their Application to Vehicle Dynamics

The automotive industry commonly uses two definitions of the suspension roll center, the Kinematic Roll Center (KRC) - of interest in studying suspension geometry, and the Force-based Roll Center (FRC) - of interest in studying steady-state vehicle dynamics. This paper introduces a third definition, the Dynamic Roll Axis (DRA) - of interest in studying transient vehicle dynamics. The location of each one of these roll centers has a unique application to vehicle design and development.

Although the physical meaning of each roll center is significantly different, the generic term “roll center” is often used without proper specification. This can lead to confusion about how roll centers influence vehicle behavior. This paper hopes to clarify some of this confusion and is organized into three parts: (1) Describes calculation methods for each of the three vehicle roll centers (for independent suspensions) as well as their relevance to vehicle dynamics; (2) Explains the relationship between the kinematic and force-based roll centers; (3) Offers recommendations on considerations for choosing roll center(s) location during vehicle design.