Abstract
BACKGROUND: Existing spinal rehabilitation mechanisms present several limitations. These include a restricted range of motion, low flexibility, and suboptimal comfort. METHODOLOGY: To overcome these issues, a novel rigid-flexible coupled spine parallel rehabilitation mechanism is proposed. The mechanism is supported by a compression spring to enhance adaptability and comfort. Initially, a simplified skeletal-muscular model of spinal motion was developed based on human spine analysis. Subsequently, a mathematical model describing the system's kinematics was established. RESULTS: Analysis of the model indicated that, under a 120 N force applied by the anterior deltoid fascicle, the mechanism exhibited a maximum deformation of 6.40 mm, meeting the design expectations. In both simulations and experimental tests of forward flexion, the maximum lumbar dorsal forward flexion angle reached 68.6°. The maximum lateral flexion angle achieved was 60.4°, while the maximum rotational angle reached 58.5°. The average maximum movement speed across different volunteers was 14.94°/s, closely aligning with the design target of 14.90°/s. Experimental measurements of the device's activity angles showed averages of 37.6° for forward flexion, 13.56° for backward flexion, 13.62° for lateral flexion (left/right), and 17.5° for rotation (left/right). All measured values were within, or closely approximated, the design range targets. CONCLUSION: The study determined both the physiological movement range of the human spine and the effective working space of the proposed mechanism. The results confirm the rationality and effectiveness of the mechanism's design.