Properties of lateral-pendulum-controlled unicycle robot in states of balance and motion

We are constructing and studying a unicycle robot which balances and steers itself by swinging its pendulum sidewards. Our unicycle robot, automatic lateral-pendulum unicycle (ALP Cycle), has three main parts: wheel, chassis and pendulum. It is an underactuated robot with only two control inputs and five degrees of freedom. Given the dynamic model of ALP Cycle which we derived previously, we have investigated several interesting properties of ALP Cycle, which are the main topics of this paper. These properties include the relationship between lean angle and pendulum angle for balanced configuration, the relationship between forward and turning speeds when ALP Cycle moves in circle, and the behaviors of coupling disturbances in longitudinal and lateral motions when in circling maneuver.