Structural Design of Connecting Rod Thumb Rehabilitation Exoskeleton

Abstract

This paper addresses the rehabilitation needs of thumb motor disorders in stroke patients by proposing a lightweight thumb rehabilitation exoskeleton based on rigid linkages. The study first analyzed the anatomical characteristics and motion mechanisms of the thumb, clarified the range of motion and torque characteristics of each thumb joint, and established a joint angle trajectory model. Based on this, a four-degree-of-freedom (DOF) linkage-based thumb exoskeleton was designed, capable of performing key movements such as opposition, flexion and extension, and pronation. The structure utilizes Bowden cables for remote actuation to reduce hand load, and kinematic and static models were established through geometric mapping and Jacobian matrix analysis. Simulation results demonstrate that the exoskeleton's output torque covers the range of human physiological requirements, and its motion trajectory is highly consistent with natural thumb movement. This design enables precise and repeatable thumb rehabilitation training for stroke and neurological injury patients, improving rehabilitation efficiency and safety. The study also noted that rigid linkage structures still have limitations in terms of human-machine compatibility and compliance. Future work will aim to optimize the exoskeleton's ergonomic performance and biomimetic features by combining flexible materials with intelligent control algorithms.