Design of a light-weight compact wearable upper limb support device using origami

Abstract

More than 80% of people who undergo severe hemiparesis after stroke continue to have impaired arm movement skills chronically and they are limited in their ability to perform ADLs due to insufficient muscle strength. Thus, forming the need for upper limb support devices. However most available support devices have considerable bulk either due to their structure or their actuation mechanism and thus deter many users from using them on a daily basis. Thus, the objective of this research was to develop a compact, wearable upper limb support device using a custom origami pattern that provides support against gravity specifically in the abduction motion, while allowing the user to horizontally flex or extend their arm. The characteristic stiffness of the model was evaluated and then verified using experiments. The model failed to accurately predict the characteristic stiffness because of non-consideration of the in-plane rotation of the equivalent spring system. Additionally, a human experiment was done to determine the muscle activity reduction and ROM. There was a decrease in muscle activity for the abduction direction of 37-48%. However, there was also an increase for the motion in horizontal flexion and extension direction of 18% and 3% respectively. The ROM of the device was determined as 510 for AB, 550 for HF and 230 for HE which was comparable to a similar soft active device. The present work introduces a new compact wearable device that provides support against gravity and shows promising results for the future development of soft passive assistive devices in assisting other motions using origami.