Mechanical and trajectory design of wearable Supernumerary Robotic Limbs for crutch use

Abstract

The Supernumerary Robotic Limbs (SRL) is a wearable robot that augments its user with two robotic limbs, kinematically independent from the user's own limbs. This thesis explores the use of the SRL as a hands-free robotic crutch for assisting injured or elderly people. This paper first details the mechanical and material design choices that drastically reduced the weight of this SRL prototype, including advanced composite materials, efficient joint structure, and high-performance pneumatic actuators. The latter half of this paper characterizes the biomechanics of both traditional crutch-assisted and SRL-assisted ambulation, models this gait pattern with an inverted pendulum system, and derives equations of motion to create a simulation that examines the effect of various initial parameters. Finally, an optimum set of initial parameters is identified to produce a successful SRL-assisted swing.