Experimental analysis of chaos in underactuated electromechanical systems

An underactuated system is a kind of non-autonomous robotic system in which there are more links than actuators. The complexity of the dynamical behav ior of these systems allows a wide variety of steady-state responses. The r econstruction of attractors based on time series obtained from measurements of one of the variables of a two-link, planar, underactuated robot called Pendubot, is developed. Time-delay coordinates, average mutual information, and percentage of false nearest neighbors' methods are used to reconstruct the invariant sets. It is shown that, under the action of a periodic torqu e, the Pendubot can display a variety of steady-state dynamics, including s trange attractors.