  The steering control of an autonomous unicycle is considered. The underlying
dynamical model of a single rolling wheel is discussed regarding the steady
state motions and their stability. The unicycle model is introduced as the
simplest possible extension of the rolling wheel where the location of the
center of gravity is controlled. With the help of the Appellian approach, a
state space representation of the controlled nonholonomic system is built in a
way that the most compact nonlinear equations of motions are constructed. Based
on controllability analysis, feedback controllers are designed which
successfully carry out lane changing and turning maneuvers. The behavior of the
closed-loop system is demonstrated by numerical simulations.
