Biofeedback Speeds Adaptation to Exoskeleton Gait Assistance

Exoskeletons may enhance mobility, but users require extensive training to receive their full benefit. While augmented feedback can accelerate motor learning, it remains difficult to apply for exoskeleton gait assistance given that desired changes depend on complex multi-joint coordination and user actions are coupled to device control dynamics. We developed a visual biofeedback system to guide novice users of an ankle exoskeleton to modify their ankle joint kinematics and foot placement toward patterns associated with improved energy economy. Biofeedback-based training doubled the energy savings from exoskeleton use. Individuals who trained with biofeedback (N = 13) achieved a 23.5% $\pm ~12.6$ % (p = 2e-5) reduction in metabolic cost of walking with assistance, compared to a 11.8% $\pm ~20.9$ % (p = 0.06) reduction for a control group (N = 13). Biofeedback enabled new exoskeleton users to achieve benefits comparable to fully adapted users in one-quarter of the time. Participants had not fully adapted after the hour-long training session with biofeedback, underscoring the task's difficulty and suggesting that greater benefit from exoskeletons might be unlocked with continued use of this approach. Energy savings were associated with increased exploration and progression toward lower-cost gait parameters in task-relevant dimensions. Our findings demonstrate that biofeedback can accelerate motor adaptation to exoskeletons, potentially enhancing their effectiveness and promoting broader device adoption.