Influence of a 3-DoF Ankle Exoskeleton on Dynamic Stability During Slip Recovery

Lower-limb exoskeletons offer potential to support balance recovery during perturbed walking, yet the biomechanical effects on dynamic stability remain poorly understood. This study investigated how wearing a 3-DoF ankle exoskeleton influences the recovery response and dynamic stability following forward falling slip perturbations during treadmill walking. Twelve healthy young adults experienced slip perturbations while walking with and without the exoskeleton. Anteroposterior margin of stability (MoS), wholebody angular momentum, and spatiotemporal gait parameters were evaluated for baseline walking and eight consecutive recovery steps without exoskeleton assistance. Results revealed significant effects of the recovery steps on all metrics, but no interaction between condition and recovery step. Wearing the exoskeleton did not affect anteroposterior MoS or step length. However, the exoskeleton induced a persistent increase in step width and led to localized changes in rotational dynamics on the perturbed side. These findings demonstrate that a 3-DoF ankle exoskeleton does not compromise sagittal plane stability during slip recovery, even without active assistance. ... mehrThey also highlight the importance of analyzing multi-step recovery dynamics when designing balance-assistive exoskeleton controllers, as the exoskeleton affects not only the first recovery step but also subsequent recovery steps.