Design Improvements to the Float Upper-Limb Exoskeleton Better Mimics the Glenohumeral Complex Kinematics

The shoulder glenohumeral complex stands out as one of the most complex structures within the human body. Designing a system that can effectively interface with it poses a significant challenge for researchers. In this study, we propose a methodology based on evaluating various metrics to assess the performance of new kinematic solutions for mimicking the glenohumeral complex. The proposed method is demonstrated on an existing design (Float) of an upper-limb exoskeleton. The results show a successful expansion of the reachable workspace and enhancement of the shoulder internal-external rotation. The improvements ensure the necessary range-of-motion for the patient’s natural use of the exoskeleton. Specifically, the existing Eulerian wrist architecture is replaced with a 3-degree-of-freedom RPY wrist to better resemble the glenohumeral shoulder joint complex. This study also explores the trade-offs between these enhancements and the desired system manipulability.