Shock Absorber Mechanism Based on an SMA Spring for Lightweight Exoskeleton Applications

Abstract

Wearable exoskeletons have generally been designed to enhance user strength or to reduce user fatigue. Two areas that have often been overlooked are that exoskeletons should increase user safety and have increased durability for use in extreme environments. In this paper, we developed an SMA spring-based shock absorption module for an exoskeleton or a quadruped walking robot, which can provide increased protection to the user during high-impact events in an extreme environment. We analyzed the impact force during the collision between the module and the ground based on impulse and momentum theories. The shock absorber module can be reused by exploiting the inherent shape memory characteristics of the SMA spring after every use. We confirmed that the spring constant of the SMA spring and the maximum allowable length affect the impulse reduction, and the results showed that the latter has a greater influence on impulse reduction.