Design of Elbow Joint Mechanism with Biomimetic Tendon-Ligament Arrangement by Elastic Belts

This paper newly proposes an elbow-like joint mechanism designed with superior safety and versatility. Humans possess the dexterity to perform complex tasks and flexibility to adjust the elasticity of the body. These abilities are realized by joint structures in which bones are constrained by muscles, tendons, and ligaments. In this manuscript, we therefore propose a novel elbow joint mechanism that uses a three-dimensional skeletal model and elastic belts made of polyurethane by means of mimicking a bio-articulated joint, in which the bones are restrained by ligaments. First, the structure of the human elbow joint is described in order to design the mechanical ligament structure. Next, the elbow joint mechanism developed according to the human ligament arrangement will be introduced, and its motion will be empirically demonstrated by flexion movement. The performance of the developed elbow joint mechanism is evaluated by tensile and compression tests. In addition, we estimate the joint stiffness by experimental estimation in order to obtain a dynamic mathematical model of the mechanism. Finally, the dynamic model is explicitly derived and the physical characteristics of the elbow joint mechanism are reported.