The Roll-Centre Concept in Vehicle Handling Dynamics

Abstract

The roll-centre concept has been in use since the 1930s, but did not have its source in a single definitive paper. Although it is defined by the SAE in terms of forces, many authors introduce the concept as a kinematic one. The kinematic and force roll-centres are really diyerent points, and should be distinguished. The kinematic roll-centre is a difficult concept when the underlying principles are considered, and is only really comprehensible if the vehicle is considered to move with small lateral acceleration. The force roll-centre may be developed using force analysis only, and is comprehensible for high lateral acceleration. A new definition of the roll-centre is proposed. The incremental roll-centre is defined. The various approximations involved in the standard constructions are considered, which are different for the two types of roll-centre, these only being equivalent for an idealized mechanism. Some difficulties in the experimental measurement of the force roll-centre are considered, especially for significant roll angles. The geometric constructions for the roll-centres of various types of suspension are discussed.