Lower Limb Exoskeleton Design Based on Knee Joint Assistance

Abstract

Human mobility is vital to daily activities and can be directly linked to the living quality. This is an especially severe problem for the patients with walking dysfunction. There is a great need to develop viable mobility solutions to assist individuals and improve their living quality. Wearable gait-assisted exoskeletons are an effective solution to this growing problem. This paper presents a passive lower limb exoskeleton which can work on hip and knee joints for gait assistance. The hip exoskeleton is designed based on specially shaped torsion springs that work with cams for gravity compensation of the human thigh, converting the torque of the built-in torsion springs into a balanced torque of the hip and knee joints in the later stages of the gait stance phase to overcome the effects of gravity. The knee exoskeleton is designed with reference to a new spring-loaded gravity balanced structure used to carry single-degree-of-freedom rotational loads. When worn, it can help the lower leg to push out during gait swing state to compensate for falls due to the lack of lower leg swing. After the exoskeleton prototype was completed, 3D motion capture experiments were performed to obtain gait parameters. Finally, the effectiveness of the exoskeleton in assisting patients with walking dysfunction was verified using OpenSim simulation software.