In particular, in this review paper we will address assistive
strategies of lower-limb exoskeletons utilized to supply additional
energy for daily-life movements of healthy young and elderly
people and those suffering from lower-limb muscular weakness
or disabilities. Reported studies will be categorized according to
the high-level control strategy, not on the employed exoskeleton:
from this point of view, the devices specifically addressing neurorehabilitation
or gait-training – e.g. LOPES [5], ALEX II [24] – will
not be included directly, since the rehabilitation treatment of these
systems aims to override the user’s volitional movements and help
them recover from motor damages (in this way, the human–robot
interaction is lowly bidirectional). Nevertheless, some of these
systems could also be employed in a motion assistive paradigm
(even if their usability is intrinsically limited by the frame-fixed
mechanical architecture), and the related outcomes are reported
in this work