A Multimodal Knee Exoskeleton for Fracture Rehabilitation

This paper presents the development and experimental validation of a novel multimodal knee joint exoskeleton system designed for fracture rehabilitation. The system aims to alleviate the adhesion and stiffness of knee joint, improving the range of motion and restoring lower limb mobility. The exoskeleton comprises two degrees of freedom: flexion and traction. The flexion motion utilizes a four-bar mechanism simulating the instantaneous center trajectory to realize biomimetic knee joint flexion. Velocity planning is applied to stably control the motion of exoskeleton. The traction motion operates independently of flexion motion, employing four linear actuators to provide continuous traction to the knee joint. Meanwhile, inflatable airbags are controlled to assist patients to adaptively match the exoskeleton shell dimensions, enhancing effectiveness of traction training. Finally, this paper developed three experiments to assess the exoskeleton system, including the test of the range of flexion motion, flexion motion stability, and effectiveness of traction motion.