Kinematics of a steering tyre with adjustable caster

This paper presents the kinematics of a steerable tyre with a variable caster. It serves as a first step towards developing the theory of variable caster steering in which wheel camber is controlled by the variable caster. The homogeneous transformation was utilised as a tool to develop the kinematics. The wheel camber, extracted from the kinematics, was expressed as a function of steering angle and suspension parameters in general case. The movement of the ground-contact point along the tyre perimeter was also taken into account. The kinematics was developed without small-angle-approximation. Therefore, the kinematic model is applicable to the case of the variable caster. A practical mechanism for the variable caster was also suggested to introduce the idea of the task. The required kinematics of such suspensions is derived from the general case to provide a visual understanding. The kinematics was then validated by a multi-body model built in ADAMS software.