Design of mechanism and kinematic analysis of robotic exoskeleton of hand for rehabilitation

Robotic hand exoskeletons are increasingly recognised as effective tools for rehabilitation yet replicating the human hand’s intricate kinematics poses significant design challenges. This study presents the design and kinematic analysis of a robotic hand exoskeleton developed to enhance rehabilitation therapies for patients with impaired motor function. A design research methodology was employed to define key objectives, including adjustable mechanism design, safe force application, integration of surface EMG sensors for real-time feedback, and customisable grasping patterns. The process began with a detailed kinematic study of the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints to establish constraints and motion requirements. Building on these findings, a three-link, three-degree-of-freedom mechanism inspired by the extensor tendon system was developed to replicate natural finger movements. Iterative refinements ensured adaptability to different hand sizes, prevention of hyperextension, and compatibility with active, assistive, and resistive rehabilitation modes. Kinematic analysis using modelling and simulations verified the device’s ability to reproduce natural range of motion, while dynamic analysis confirmed its structural integrity and safety under operational loads. The proposed exoskeleton demonstrates the potential of combining biomechanical insights, adaptive mechanisms, and user-centred design research methodologies to deliver a customisable, safe, and effective rehabilitation solution.