Hybrid assistive strategy aims to control the exoskeleton by
applying different assistive strategies: BLEEX (3.7.1) adopts a
force controller in swing phase and a position controller in
stance phase; Pneumatic muscles orthosis by T. Yeh et al. (3.7.2)
utilizes a model-based controller in stance phase and a predefined
trajectory controller in swing phase; the AIT leg exoskeleton-I
(3.7.3) firstly predefines the gait trajectory offline and then uses
a fuzzy controller to adjust the trajectory online. For a specific gait
state, the efficacy of assistance could be improved. However, the
transition between each strategy should be taken into account to
avoid discontinuity or uneven outputs.