The Design and Characterization of a Variable-Stiffness Compliant Knee Joint for Enhanced Mobility

摘要

Abstract The knee joint, serving as a critical nexus in human locomotion, presents a unique set of challenges and opportunities for enhancing mobility through assistive technologies. Assistance with knee function is frequently required due to conditions like arthritis, injuries, or age-related changes, affecting one’s ability to walk and carry out daily tasks. Compliant mechanisms integrate flexible members that go under large deformation when loaded which is very similar to the nature as opposed to relative motion generation between adjunct links as in rigid mechanisms. Their ability to be manufactured in a single piece, coupled with enhanced performance due to the absence of friction loss, positions them as an excellent choice for a range of applications, particularly in the development of robotic and biomedical devices. In this study, we designed a compliant knee joint featuring variable stiffness, characterized by initially pre-buckled beams, to mimic the nonlinear stiffness behavior seen in the human gait cycle. We designed various combinations of pre-buckled beams having different geometries to analyze the torque and angular deformation as well as force and displacement relations. The knee joints are built as a single piece using a dual extruder 3D printer.