Human Wrist Rehabilitation: Mechanical Design and Development of EDUSA®PRO Robotic Solution

The rehabilitation of wrist motor functions following neurological injuries, such as stroke, requires targeted, repeatable, and adaptive therapies to promote functional recovery and neuroplasticity. Robotic systems for rehabilitation have emerged as valuable tools, offering precise assessments of a patient's abilities and progress while accurately adapting training difficulty levels. Combined with real-time feedback, these systems enhance patient engagement, motor learning, and overall rehabilitation outcomes. However, despite considerable advancements in robotic rehabilitation technology, designing systems that replicate the human wrist's complex biomechanics, including human-like torque generation and a full range of motion, remains challenging. Constraints related to mechanical complexity, size, and portability pose additional barriers to widespread adoption in both clinical and home-based settings. This paper introduces a custom mechanical design solution implemented in a novel robotic end-effector specifically designed for human wrist rehabilitation, named EDUSA® PRO, which provides three actuated degrees of freedom to support complex wrist movements. We describe the design and development of a custom-designed motion system, which allows to meet both range of motion and torque values of the unimpaired human wrist. This goal is realized via the design of custom-made rails and rolls system that allows to replicate simultaneously movements along the three degrees of freedom, with smooth motion and without interference, and through the selection of a power transmission system purposely sized to achieve human torque values. Results demonstrate that EDUSA® PRO closely replicates the human wrist's capabilities while maintaining a compact and ergonomic design, making it one of the more competitive end-effector robots for upper limb rehabilitation on the market.