Haptic Adaptive Feedback to Promote Motor Learning With a Robotic Ankle Exoskeleton Integrated With a Video Game

Abstract

Background: Robotic devices have been used to rehabilitate walking function after stroke. Although results suggest that post-stroke patients benefit from this non-conventional therapy, there is no agreement on the optimal robot-assisted approaches to promote neurorecovery. Here we present a new robotic therapy protocol using a grounded exoskeleton perturbing the ankle joint based on tacit learning control. Method: Ten healthy individuals and a post-stroke patient participated in the study and were enrolled in a pilot intervention protocol that involved performance of ankle movements following different trajectories via video game visual feedback. The system autonomously modulated task difficulty according to the performance to increase the challenge. We hypothesized that motor learning throughout training sessions would lead to increased corticospinal excitability of dorsi-plantarflexor muscles. Transcranial Magnetic Stimulation was used to assess the effects on corticospinal excitability. Results: Improvements have been observed on task performance and motor outcomes in both healthy individuals and post-stroke patient case study. Tibialis Anterior corticospinal excitability increased significantly after the training; however no significant changes were observed on Soleus corticospinal excitability. Clinical scales showed functional improvements in the stroke patient. Discussion and Significance: Our findings both in neurophysiological and performance assessment suggest improved motor learning. Some limitations of the study include treatment duration and intensity, as well as the non-significant changes in corticospinal excitability obtained for Soleus. Nonetheless, results suggest that this robotic training framework is a potentially interesting approach that can be explored for gait rehabilitation in post-stroke patients.

Wearable Biofeedback Improves Human-Robot Compliance during Ankle-Foot Exoskeleton-Assisted Gait Training: A Pre-Post Controlled Study in Healthy Participants

“…Contrarily to the findings of this study, the human-robot interaction torque feedback from [ 10 ] was not able to detect the motor progress of the users. On the other hand, the findings from [ 9 , 11 ] suggest improved motor learning upon biofeedback training, similarly to this study. However, both studies [ 9 , 11 ] include non-wearable BSs while the proposed biofeedback is provided through a fully wearable BS allowing ambulatory use and daily practice, which accelerates motor learning [ 4 ].…”

“…On the other hand, the findings from [ 9 , 11 ] suggest improved motor learning upon biofeedback training, similarly to this study. However, both studies [ 9 , 11 ] include non-wearable BSs while the proposed biofeedback is provided through a fully wearable BS allowing ambulatory use and daily practice, which accelerates motor learning [ 4 ]. Moreover, the study [ 11 ] only addressed dorsiflexion/plantar flexion movements while sitting.…”

“…This hypothesis is also followed by [ 10 ] with hip and knee exoskeletons, and it is reinforced by [ 9 ], concluding that human-robot interaction-based biofeedback is more effective than EMG-based biofeedback to improve patient’s compliance with the robot movement. Contrarily to [ 9 , 10 , 11 ], the proposed strategies followed a user-centered design, allowing to personalize the biofeedback (namely, the training gait phase and training threshold) according to the user’s imminent needs; thus, aiming for low cognitive effort and user satisfaction. Moreover, contrarily to [ 9 , 10 , 11 ], the proposed biofeedback strategies and physiotherapist-oriented control strategies are implemented in a fully wearable BS and ankle-foot exoskeleton, allowing ambulatory use and daily practice.…”

“…This study determined the effects of the proposed biofeedback strategies on healthy participants as in [ 11 ]. The healthy participants were challenged to reduce their interaction with the ankle–-oot exoskeleton through active walking, aiming to improve human-robot compliance.…”

“…Only one study reported the use of biofeedback with an ankle-foot exoskeleton, using a game based on measured ankle angle to encourage patients to perform simple dorsiflexion and/or plantar flexion movements while sitting (which is not functional gait training) [ 11 ]. A gyrocopter character is displayed on a non-wearable screen and moves upwards/downwards according to the user’s dorsiflexion/plantar flexion movements that should follow the trajectory delineated through gas bottle characters [ 11 ].…”