Self-organized control of bipedal locomotion by neural oscillators in unpredictable environment

Abstract

A new principle of sensorimotor control of legged locomotion in an unpredictable environment is proposed on the basis of neurophysiological knowledge and a theory of nonlinear dynamics. Stable and flexible locomotion is realized as a global limit cycle generated by a global entrainment between the rhythmic activities of a nervous system composed of coupled neural oscillators and the rhythmic movements of a musculo-skeletal system including interaction with its environment. Coordinated movements are generated not by slaving to an explicit representation of the precise trajectories of the movement of each part but by dynamic interactions among the nervous system, the musculo-skeletal system and the environment. The performance of a bipedal model based on the above principle was investigated by computer simulation. Walking movements stable to mechanical perturbations and to environmental changes were obtained. Moreover, the model generated not only the walking movement but also the running movement by changing a single parameter nonspecific to the movement. The transitions between the gait patterns occurred with hysteresis.

Dynamic Hebbian learning in adaptive frequency oscillators

“…Dynamic Hebbian learning for adaptive oscillators has an important implication in the design of CPG models. Actually, coupled nonlinear oscillators are often used for modeling CPGs [6,10,13,23], but the coupling has to be defined by hand and this is a non-trivial task. By using adaptive oscillators, one could build CPGs that can dynamically adapt their frequencies and consequently, create a desired pattern of oscillations.…”

“…Models of Josephson junctions [22], lasers, central pattern generators (CPGs) [6,10,13,23], associative memories [2,18] and beat perception [8,14] are a few examples that show the importance of oscillators in modeling and control.…”

Neural learning of embodied interaction dynamics

“…Point attractor dynamics is a standard concept in neural model of memory functions (Hopfield, 1982), which exactly does a kind of assimilation. Use of a single limit cycle attractor has been experimented in robot motion control (Taga et al, 1991;Rizzi and Koditschek, 1993). An important issue would be allowing many distinct attractors in a closed-loop embodied interaction dynamics (as contrasted with the pure internal dynamics in case of memory models) and enabling it to migrate from one to another; 2. spontaneous dynamics and spatiotemporal patterns: in Piaget's stage theory, the initial schemata are created through exploration by reflexes.…”

Dynamic Movement Primitives -A Framework for Motor Control in Humans and Humanoid Robotics

“…The idea of using dynamic systems for movement generation is not new: motor pattern generators in neurobiology [13,14], pattern generators for locomotion [15,16] [24,25]. As shown in …”