Design of a cable-driven active leg exoskeleton (C-ALEX) and gait training experiments with human subjects

Robotic rehabilitation devices are attractive to physical therapists. Various leg exoskeletons have been developed during the past decade and have been used in gait training. Traditional exoskeletons usually have a complex structure and add extra inertia to the wearer's leg, which may change their natural gait. In this paper, we present the design of a cable-driven active leg exoskeleton (C-ALEX) for human gait training. The advantages of cable-driven designs are that they have a simpler structure, add minimal inertia to the human limbs, and do not require precise joint alignment. C-ALEX employs the “assist-as-needed” control strategy to help the ankle center move along a prescribed path. An experiment with 6 healthy subjects was conducted who walked with C-ALEX on a treadmill. The results showed that C-ALEX is capable of helping the subjects better track a prescribed ankle path.