Recent studies on ankle exoskeletons have shown the feasibility of this technology for post-stroke gait rehabilitation. The main contribution of the present work is a comprehensive experimental analysis and protocol that focused on evaluating a wide range of biomechanical, usability and users' perception metrics under three different walking conditions: without exoskeleton, with an ankle exoskeleton unpowered, and with an ankle exoskeleton powered. To carry out this study, we developed the ABLE-S exoskeleton that can provide time-adapted ankle plantarflexion and dorsiflexion assistance. Tests with five participants with chronic stroke showed that walking with the ABLE-S exoskeleton significantly corrected foot drop by 25 % while reducing hip compensatory movements by 21 %. Furthermore, asymmetrical spatial gait patterns were significantly reduced by 51 % together with a significant increase in the average foot tilting angle at heel strike by 349 %. The total time to don, doff and set-up the device was of 7.86 ± 2.90 minutes. Finally, 80 % of the participants indicated that they were satisfied with their walking performance while wearing the exoskeleton, and 60 % would use the device for community ambulation. The results of this study add to the existing body of evidence supporting that ankle exoskeletons can improve gait biomechanics for post-stroke individuals.

<p>The effectiveness of robotic exoskeletons for post-stroke gait rehabilitation might be limited as the control parameters of these devices do not adapt to key biomechanical descriptors. The main contribution of this study is to examine post-stroke gait with the aim of finding relationships between exoskeleton control parameters and a comprehensive set of biomechanical metrics. Five stroke survivors walked with the assistance of a wearable ankle exoskeleton (ABLE-S) using different levels of plantarflexion (PF) and dorsiflexion (DF) peak torque, as well as different timings of PF peak torque. We found that DF peak magnitude had significant negative relations with the temporal symmetry index (p = 0.033) and the paretic foot absolute angle at heel strike (p = 0.019). Changes in the applied PF assistance parameters were significantly correlated with a high variety of temporal and spatial parameters, e.g., walking speed (p = 0.009), stride length (p = 0.011), non-paretic step length (p = 0.024), foot clearance (p = 0.003) and hip hiking (p = 0.038), and the muscle activation for the non-paretic side, e.g., Tibialis Anterior (p = 0.049) and Gastrocnemius Medialis (p = 0.049). Based on our results, we propose a set of control laws for adapting the assistance of ankle exoskeletons that will be evaluated in future work.</p>

<p>The effectiveness of robotic exoskeletons for post-stroke gait rehabilitation might be limited as the control parameters of these devices do not adapt to key biomechanical descriptors. The main contribution of this study is to examine post-stroke gait with the aim of finding relationships between exoskeleton control parameters and a comprehensive set of biomechanical metrics. Five stroke survivors walked with the assistance of a wearable ankle exoskeleton (ABLE-S) using different levels of plantarflexion (PF) and dorsiflexion (DF) peak torque, as well as different timings of PF peak torque. We found that DF peak magnitude had significant negative relations with the temporal symmetry index (p = 0.033) and the paretic foot absolute angle at heel strike (p = 0.019). Changes in the applied PF assistance parameters were significantly correlated with a high variety of temporal and spatial parameters, e.g., walking speed (p = 0.009), stride length (p = 0.011), non-paretic step length (p = 0.024), foot clearance (p = 0.003) and hip hiking (p = 0.038), and the muscle activation for the non-paretic side, e.g., Tibialis Anterior (p = 0.049) and Gastrocnemius Medialis (p = 0.049). Based on our results, we propose a set of control laws for adapting the assistance of ankle exoskeletons that will be evaluated in future work.</p>

Recent studies on ankle exoskeletons have shown the feasibility of this technology for post-stroke gait rehabilitation. The main contribution of the present work is a comprehensive experimental analysis and protocol that focused on evaluating a wide range of biomechanical, usability and users' perception metrics under three different walking conditions: without exoskeleton, with an ankle exoskeleton unpowered, and with an ankle exoskeleton powered. To carry out this study, we developed the ABLE-S exoskeleton that can provide time-adapted ankle plantarflexion and dorsiflexion assistance. Tests with five participants with chronic stroke showed that walking with the ABLE-S exoskeleton significantly corrected foot drop by 25 % while reducing hip compensatory movements by 21 %. Furthermore, asymmetrical spatial gait patterns were significantly reduced by 51 % together with a significant increase in the average foot tilting angle at heel strike by 349 %. The total time to don, doff and set-up the device was of 7.86 ± 2.90 minutes. Finally, 80 % of the participants indicated that they were satisfied with their walking performance while wearing the exoskeleton, and 60 % would use the device for community ambulation. The results of this study add to the existing body of evidence supporting that ankle exoskeletons can improve gait biomechanics for post-stroke individuals.