Improving stability of people wearing a lower extremity Wearable Exoskeleton (WE) is one of the biggest challenges in the field. The goal of this preliminary study was to improve balance recovery from perturbations in people with incomplete Spinal Cord Injury (SCI) assisted by a WE with specifically developed balance controller. The WE has actuated ankle and knee joints, which were controlled by using a body sway-based balance controller. Two test pilots participated in 5 training sessions, devoted to enhance the use of the robot, and in pre/post assessments. Their balance during quiet standing was perturbed through pushes in forward direction. The controller was effective in supporting balance recovery in both tests pilots as reflected by a smaller sway amplitude and recovery time when compared with a minimal impedance controller. Moreover, the training resulted in a further reduction of the sway amplitude and recovery time in one of the test pilots whereas it had not an additional beneficial effect for the other subject. In conclusion, the novel balance controller can effectively assist people with incomplete SCI in maintaining standing balance and a dedicated training has the potential to further improve balance.

This work was devoted to preliminary test the Achilles ankle exoskeleton and its NeuroMuscular Controller (NMC) with a test pilot affected by incomplete spinal cord injury. The customization of the robot controller, i.e. a subject-specific tailoring of the assistance level, was performed and a 10-session training to optimize human-robot interaction was finalized. Results demonstrated that controller tuning was in line with the functional clinical assessment. NMC adapted to the variable walking speed during the training and the test pilot was successfully trained in exploiting robotic support and also improved his performance in terms of walking speed and stability. After the training, a higher speed could also be achieved during free walking and hence a slight unexpected rehabilitation effect was evidenced.