Conceptual Design and Preliminary Experiment of an Orthopedic Rehabilitation Exoskeleton Based on the Coupled Movable Pulley Mechanism (CMPM)

During the bone tissue proliferative phase following fracture surgery, axial mechanical stimulation has been shown to facilitate bone healing. This study introduces the mechanism, conceptual design and preliminary experiment of an innovative lower limb orthopedic rehabilitation exoskeleton utilizing the Coupled Movable Pulley Mechanism (CMPM). Unlike conventional exoskeletons that merely offer assistive torque for knee movement, the effector of this exoskeleton additionally exerts controlled axial load at the femur or tibia fracture sites to provide tunable mechanical stimulation. This paper delves into the foundational principles of CMPM and design of the exoskeleton, develops a cable-driven force feedback control system for axial load exertion and knee joint support, and validates CMPM's anticipative functions by experiments. The results suggest that the proposed effectors play a dual role in post-fracture rehabilitation, i.e., providing axial loading stimulation and knee support. This research will potentially expedite post-surgical recovery in orthopedics, enhancing rehabilitation efficiency and improving patient outcomes.