Document Type

Honors Thesis

Publication Date

Spring 2019


The shoulder joint is an extremely complex joint, with a wide range of motion (ROM), which makes designing an upper extremity exoskeleton a complicated task. This thesis presents a 3-degree-of-freedom (DOF) exoskeleton with a modified double parallelogram mechanism (DPM) that fits any wearer independent of their biological frame. The DPM is remarkably useful in wearable robotics. The mechanism creates a remote center of rotation about the shoulder joint while remaining unobtrusive and not colliding with the wearer’s body. Its fixed link lengths, however, requires it to be specially fitted to each individual user. This is inconvenient for most exoskeletons that utilize a DPM, since wearers often vary in body shape, size, and build. By connecting the two parallelograms with a mediating link and implementing a sliding-pin joint, the proposed modified DPM allows for a much larger ROM than the original design of the mechanism. This allows it to fit onto almost any anthropometric frame. The exoskeleton provides active assistance during flexion/extension while allowing free abduction/adduction and internal/external rotations. The experimental results demonstrate the proposed design’s ability to provide assistance during a wide range of shoulder motions.