Models of entrainment of human walking

Abstract

Stable human locomotion may be described as a non-linear limit cycle oscillator. This claim has been supported through the observation of dynamic entrainment and phase-locking to external mechanical perturbations applied at the ankle. Simple models have been developed in attempts to understand these behaviors, but have been unsuccessful at replicating experimental studies. In this manuscript, an energy-based controller was implemented on a single degree-of-freedom model, adjusting its leading leg angle at heel strike and consequently the energy dissipation of the model. Stochasticity was applied to the controller to simulate the variability which has been observed and quantified in walking. The results indicate that energy control may be responsible for entrainment in human walking, but a revised model may be required to match the experimental coefficients of variation in step duration and velocity.