Design, Development, and Evaluation of Wearable Length Fastening Devices for Use with Twisted Coiled Actuators

Abstract

Artificial muscles and compliant, large stroke linear actuators have enabled new classes of wearable robotics. However, these actuators are inefficient, needing constant power to maintain force and displacement, decreasing their utility in wearable systems. Variable length latching mechanisms alleviate this problem, matching actuator displacement, and holding force and displacement constant when the actuator is powered off. However, most existing latching designs are either not wearable, or must be disengaged manually, limiting their robotic applications. In this research, three wearable and remotely releasable latching mechanisms were designed for use in wearable robotic systems: a stepper motor with a belt and pulley; a linear ratchet; and a cam cleat. The designs were manufactured and tested, with all three designs maintaining force and displacement values up to 15N of cable tension and releasable up to 5N of cable tension. These results demonstrate the viability of integrating latches into soft wearable robotic systems.