The XoR prototype has been developed for postural control
of elderly people and persons with mobility disability [53].
XoR implements a hybrid driving concept combining pneumatic
artificial muscles and electric motors together [53,54]: the
former acts as a gravity balancer while the latter as a dynamic
compensator. The total generated torque tracks a desired value
calculated on the basis of a bio-mechanical model. The user’s
posture is given by joint angles and ground reaction forces while
the motion intention is estimated based on EMG signals. Only
simulation results were available to prove the efficacy of this
assistive strategy working with XoR.