  We investigate the sensorimotor loop of simple robots simulated within the
LPZRobots environment from the point of view of dynamical systems theory. For a
robot with a cylindrical shaped body and an actuator controlled by a single
proprioceptual neuron we find various types of periodic motions in terms of
stable limit cycles. These are self-organized in the sense, that the dynamics
of the actuator kicks in only, for a certain range of parameters, when the
barrel is already rolling, stopping otherwise. The stability of the resulting
rolling motions terminates generally, as a function of the control parameters,
at points where fold bifurcations of limit cycles occur. We find that several
branches of motion types exist for the same parameters, in terms of the
relative frequencies of the barrel and of the actuator, having each their
respective basins of attractions in terms of initial conditions. For low
drivings stable limit cycles describing periodic and drifting back-and-forth
motions are found additionally. These modes allow to generate symmetry breaking
explorative behavior purely by the timing of an otherwise neutral signal with
respect to the cyclic back-and-forth motion of the robot.
