Disorder and Homeostasis in ANIBOT A Biologically-Inspired Animal Robot.

The effects of external perturbations (or disorder) in the Hopf bifurcations of a central pattern generator (CPG) network of neurons that serves as a model for the circuit realization of ANIBOT-a biologically-inspired animal robot with four legs-are studied, analytically and computationally, from the standpoint of homeostasis. In particular, we employ recent developments in the mathematical description of homeostasis, e.g., input-output functions, to explore the CPG response to perturbations of the network connectivity, the internal dynamics of the neurons, and electronic noise as it arises in the circuit realization of ANIBOT. The patterns of locomotion (Walk, Jump, Trot, Bound, Pace, and Pronk) are controlled, mainly, by the phase dynamics of a CPG network. The results show that with the exception of the Walk and Jump gaits, the phase dynamics of all other gaits exhibit perfect homeostatic responses. In addition, a distinctive feature of the network dynamics is that, under certain conditions, the external perturbations can lead to the appearance of certain patterns, which are absent in the unperturbed system, i.e., disorder-induced pattern formation.