A model of postural coordination dynamics

Abstract

Prior research has shown that voluntary postural movement is characterized by stable in-phase and antiphase hip–ankle coordination modes. Prior modeling of coordination dynamics does not capture the stable fixed-points, phase transitions and hysteresis found in hip–ankle coordination. In this article a model was created to capture the dynamics of hip–ankle postural coordination. The present model follows the synergetic approach and uses two nonlinear oscillators to capture the dynamics of hip–ankle coordination. Terms for symmetry breaking and additive stochastic noise are included in the model. The model captures phase transitions from in-phase to antiphase coordination as movement frequency is scaled up and from antiphase to in-phase coordination as movement frequency is scaled down. The model also exhibits hysteresis, with phase transitions occurring at different movement frequencies as the control parameter is scaled up and down.