Introduction and initial exploration of an Active/Passive Exoskeleton framework for portable assistance

Assistive devices such as exoskeletons are capable of providing rehabilitative improvement and independence for individuals suffering from musculoskeletal conditions. Typical devices use either active assistance methods such as DC motors or passive methods such as springs. Active methods require a continuous power input, while passive methods are limited by user capability. This work introduces an Active/Passive EXoskeleton (APEX) framework. This device can passively provide continuous assistance, only requiring energy to change the dynamic properties of the passive state. The first prototype (APEX-α) is introduced and tested on six healthy subjects who performed hammer curls. It was found that changes in the passive state of the APEX-α affect the number of curls performed by an individual. By changing the passive state of the exoskeleton, increases in curl count of 65 - 92% were observed. This indicates the potential for such devices to provide assistance to an individual through the use of lightweight, energy efficient active/passive actuators.