Exploration of Locking and Unlocking Mechanisms for an Upper-Body Exoskeleton to Support Leaning
Shoulder and back pain are two of the most common work-related injuries in the world. Many occupations require hours of continuous and prolonged leaning, bending over, stooping, and reaching. This leaves workers with short-term discomfort and soreness, long-term back, shoulder, and arm pain, and in some cases, nerve damage. Wearable exoskeletons are the product of an emerging market that aims to alleviate the continual stress on workers performing such tasks. However, the majority of existing exoskeletons are rigid and can restrict user movement or cause discomfort, and some require an external power source. The goal of this thesis is to develop core mechanical components of a lightweight and compact flexible-to-rigid arm exoskeleton that can assist a user in providing upper body support for leaning, stooping, and kneeling tasks. The primary focus of the proposed exoskeleton in this paper is the locking mechanism, which consists of a series of orthogonal joints comprised of two serrated locking plates separated by a conical thrust spring. The passive locking mechanism can be engaged and disengaged by adjusting the tension on a cable that runs through the device. Three iterative prototypes are developed and evaluated to determine the optimal joint type, locking mechanism, and flexible-to-rigid toggle mechanism. The final prototype is a 2-degree-of-freedom (DOF) single joint module with precise mechanical locking mechanisms in a compact, 3D-printed housing. This preliminary design serves as a large stepping stone to developing a robust wearable arm exoskeleton.