Design of an artificial muscle actuated finger towards biomimetic prosthetic hands

This paper focuses on the design and modeling of a prosthetic finger for children. Conventional prosthetic hands are simple grippers that only restore the very basic grasping capabilities of the human hand. Novel design methodologies are required in order to address the issue of low functionality of prosthetic hands while still meeting their mass and size requirements. We propose a biomimetic approach to prosthetic hand design. The musculoskeletal characteristics of the human hand are studied in order to extract elements that are essential in the design of a biomechanically accurate hand. This paper presents a 4 DOF finger design that closely mimics the size and kinematics of the human finger. Our design proposes to use SMA-driven tendon wires that are directly attached to the finger structure, in a manner similar to the natural tendons and muscles. A kinematic analysis of the proposed finger, which defines the relationship between the motion of its joints and the corresponding SMA artificial muscle contraction ranges, is presented. The results of a torque analysis, carried out to evaluate SMA wire diameter and actuation forces required, is also presented