The evolution to bipedalism forced humans to develop suitable strategies for dynamically controlling their balance, ensuring stability, and preventing falling. The natural aging process and traumatic events such as lower-limb loss can alter the human ability to control stability significantly increasing the risk of fall and reducing the overall autonomy. Accordingly, there is an urgent need, from both end-users and society, for novel solutions that can counteract the lack of balance, thus preventing falls among older and fragile citizens. In this study, we show a novel ecological approach relying on a wearable robotic device (the Active Pelvis Orthosis, APO) aimed at facilitating balance recovery after unexpected slippages. Specifically, if the APO detects signs of balance loss, then it supplies counteracting torques at the hips to assist balance recovery. Experimental tests conducted on eight elderly persons and two transfemoral amputees revealed that stability against falls improved due to the “assisting when needed” behavior of the APO. Interestingly, our approach required a very limited personalization for each subject, and this makes it promising for real-life applications. Our findings demonstrate the potential of closed-loop controlled wearable robots to assist elderly and disabled subjects and to improve their quality of life.

This study investigated the hypothesis that the coupled contribution of all body segments to the whole-body response during both walking and managing unexpected perturbations is characterized by similar features which do not depend on the laterality (i.e., right versus left sides), but can be influenced by the direction (e.g., north, east, south, etc.) of the perturbation. The whole-body angular momentum was estimated as summation of segmental angular momenta, while 15 young adults managed ten unexpected unilateral perturbations during walking. Then, the Principal component analysis was used to extract primitive features describing intersegment coordination. Results showed that intersegment coupling was similar even though the reactive response to the perturbations elicited more consistent motor schemes across body segments than during walking, especially in the frontal plane. The direction of the perturbation significantly affected angular momentum regulation documenting the attitude of the central nervous system to interpret multiple sensory inputs in order to produce context-dependent reactive responses. With respect to the side, results highlighted anisotropic features of the elicited motor schemes that seemed to depend on subjects' dominance. Finally, results confirm that the coordination of upper and lower body segments is synergistically achieved strengthening the hypothesis that it may result from common neural pathways.

No abstract