Non-anthropomorphic passive load-bearing lower-limb exoskeleton with a reconfigurable mechanism based on mechanical intelligence

Load-bearing walking is a demanding activity for individuals engaged in field exploration, rescue operations, and military tasks. This study introduces a non-anthropomorphic passive lower-limb exoskeleton (NAPLE) aimed at augmenting human load-bearing capacities. NAPLE adopts a reconfigurable universal-cylindrical-revolution pair (U-C-R) mechanism in each leg to passively accommodate the walking gait, thereby circumventing the misalignment limitations of motion between humans and robots widely existing in anthropomorphic exoskeletons. The topology of the mechanism can be reconfigured to a U-R mechanism via a cylindrical pair regressed in the stance phase and recruited in the swing phase, which is intelligently and automatically regulated via a purely mechanical approach. Meanwhile, a gravity compensation spring was proposed to smooth the fluctuation of the center of mass of the load to further decrease the consumption of the wearer. Prototype testing demonstrated that NAPLE can transfer an average of 87.8 % of the load weighing 30 kg to the ground in the stance phase and an average of 42.4 % while walking.