Should Ankle Exoskeletons Also Provide Assistance During Swing Phase?

This work seeks to answer the question of whether adding swing phase dorsiflexion assistance further improves performance when walking with ankle exoskeletons providing standard powered stance phase plantar flexion assistance. The purpose of this study was to evaluate how novice exoskeleton users respond to stance phase plantar flexor assistance alone vs stance phase plantar flexor assistance combined with swing phase dorsiflexion assistance. We hypothesized that combining these assistance modalities would result in decreased metabolic power, reduced muscle activity, and improved gait mechanics. Participants performed walking trials with an untethered ankle exoskeleton under various conditions: plantar flexion assistance only or combined plantar flexion and dorsiflexion assistance. A baseline condition, where the exoskeleton was mechanically disconnected but with the same added mass, was also collected. While no significant differences were observed in steady-state metabolic power, muscle activity or toe clearance, there was a strong positive correlation (0.913) between the improvements in metabolic power across different assistance conditions. This suggests that individuals who benefited from one type of assistance also tended to benefit from the other, highlighting the potential for personalized exoskeleton design and control strategies.