A lightweight passive ankle exoskeleton with dual-phase energy harvesting and stiffness adaptation.

By integrating the optimal stiffness ratio between the stance and swing phases, derived from musculoskeletal model simulations, with previously established optimal stance-phase stiffness parameters, we determined a suitable stiffness coefficient for the swing-phase spring.

Furthermore, energy recovery during the swing phase alone contributes an additional 1.67% reduction in energy expenditure, improving overall walking efficiency.