Effect of External Damping on Ankle Motion During the Swing Phase of Walking

Manipulation of human ankle dynamics during walking is essential for a smooth gait cycle. Ankle exoskeletons have generally proven positive for rehabilitation and restoration purposes. With the focus on prolonged use of such exoskeletons, there is a need to study the effect of exoskeletons’ residual dynamics on gait adaptation. Understanding such inadvertent interaction can help future intervention paradigm decisions and exoskeleton design. The current work investigates the effect of residual damping on the ankle joint during the swing phase of walking, typically the non-targeted phase of a rehabilitation paradigm. A gait adaptation study was conducted using a cable-driven ankle exoskeleton that applied external damping, both positive and negative, on nine healthy individuals. The interventions resulted in varied perturbed ankle kinematics during the swing phase showing significant reduction and amplification of ankle motion due to the applied positive and negative damping, respectively. The current study demonstrates that healthy individuals can alter their ankle impedance during the swing phase of walking without limiting the overall gait performance.