Design of a Personalized Bio-Mechanical Knee Orthosis

Abstract

Exoskeleton joints should be aligned and follow the anatomy of the person to prevent putting additional strain on the ligaments or creating skin complications through rubbing between the patient and the exoskeleton. The human knee is a challenging joint to replicate accurately since its motion is not a simple hinge joint; the knee rotates through its range of motion while the tibia extends relative to the joint center. This paper presents a powered biomechanical-inspired knee joint for an exoskeleton developed to follow the flexion-extension motion. By utilizing previous literature that used Magnetic Resonance Imaging scans to identify the relationship of flexion-extension, the design requirements for the knee mechanism were defined. The flexion-extension motion was used to determine the polynomial-shaped cam mechanism, translating the shank segment as the joint rotates. This knee joint takes advantage of Fused Deposition Modeling 3D printing, allowing the knee to be easily manufactured and customized. Motion capture and finite element analysis are used to validate the motion and mechanical strength. The final biomechanical knee joint is highly customizable and easy to manufacture.