1. A ball robot, comprising: a spherical shell; a diametric main axle; at least one pendulum pivotally coupled to the main axle; and a drive mechanism for driving said pendulum(s) comprising at least a primary drive motor and a secondary drive motor, wherein the drive motors are arranged on the pendulum(s) in a vicinity of an inner surface of the shell, the primary motor is arranged to drive said pendulum(s) for rotation about said main axis, and the secondary motor is arranged to drive said pendulum for rotation about a secondary axis.