Modeling human postural sway using an intermittent control and hemodynamic perturbations.

Area of Science:

• Biomechanics
• Control Theory
• Human Physiology

Background:

• Human quiet stance involves ground reaction forces synchronized with the cardiac cycle.
• Hemodynamic forces create endogenous perturbations, leading to postural sway.
• Understanding postural sway is crucial for human balance control research.

Purpose of the Study:

• To compare intermittent and continuous control models in replicating human-like postural sway.
• To investigate the role of hemodynamic perturbations in postural sway dynamics.
• To identify mechanisms generating human-like sway patterns.

Main Methods:

• An inverted pendulum model was used to simulate postural sway dynamics.
• Intermittent and continuous-time feedback control strategies were analyzed.
• Models were subjected to periodic and random forcing mimicking hemodynamic perturbations.
• Simulated sway was compared to human-like power law behavior (0.1-0.7Hz).

Main Results:

• Continuous control models with typical parameters failed to reproduce human-like sway.
• Intermittent control models successfully exhibited human-like sway patterns.
• Deterministic and chaotic oscillations in intermittent control were key factors.

Conclusions:

• Intermittent control strategies, not continuous ones, may explain human-like postural sway.
• Hemodynamic perturbations combined with intermittent control offer a plausible mechanism for postural sway.
• This research provides a novel perspective on the endogenous control of human balance.