Robot-Assisted Rehabilitation: Mechatronic Redesign of a Finger Exoskeleton to Improve Its Motion Tracking Capabilities

Understanding human hand movement functionality is fundamental in neuroscience, robotics, and rehabilitation. Indeed, accurate finger motion tracking in hand exoskeleton systems is essential for effective robot-assisted rehabilitation through engaging serious games in virtual reality or via a computer’s display. This approach aims to make the rehabilitation process less tedious and, hence, potentially more effective for improved outcomes in therapy. In this paper, we provide a tracking solution for rehabilitation purposes. Specifically, after analysing the methods adopted for hand motion tracking, the work focused on the mechanical redesign of FLEXO, the rehabilitative hand exoskeleton developed by the Department of Industrial Engineering at the University of Florence. A non-visual approach was adopted to overcome the limitations of vision-based tracking. The redesign centred on the FLEXO’s Finger Mechanism, utilising two new rotary encoders for the patient’s finger’s MetaCarpoPhalangeal (MCP) and Proximal InterPhalangeal joint rotations. A novel temporary module was introduced for the MCP rotation measurement. Afterwards, structural finite element analyses ensured the components’ reliability. Finally, data acquisition was performed and evaluated to correlate the finger and device kinematics and update the representation of the finger’s motion in the serious game previously developed in the Unity Game environment.