Effects of Hip Adduction-Abduction Exoskeleton-Controlled Step Width on Mediolateral Gait Balance During Walking

Mediolateral balance during walking is a critical aspect of functional mobility, particularly in populations with neuromuscular disorders. Step width is one of the key gait parameters influencing balance, and mediolateral hip exoskeletons have emerged as potential tools to modulate step width for improved stability. This study investigated the effects of exoskeleton-controlled step width on mediolateral gait balance represented by various gait balance metrics, including trunk sway, margin of stability (MoS), net external moment, and step width variability, in healthy individuals. Using a reinforcement learning-based control framework, the exoskeleton achieved precise step width control with an average error of 0.46 cm. Results revealed that the step width has a strong positive correlation with trunk sway ($R^{2}=0.9795$), margin of stability ($R^{2}=0.8948$), and net external moment ($R^{2}= 0.9188$ ), reflecting a trade-off between stability and effort. Step width variability was unaffected, suggesting no destabilizing impact from controlled step width adjustments. These findings provide valuable insights into the design and optimization of exoskeletons for enhancing mediolateral stability in clinical and rehabilitation settings.