Bionic Design and Kinematic Evaluation of a Stiffness-Adjustable Spinal Exoskeleton for Trunk Support

In recent years, the field of medical rehabilitation utilizing back-support exoskeleton has demonstrated significant potential for application. However, existing exoskeletons still present issues such as insufficient comfort and safety. This paper proposes the design of a passive exoskeleton with variable stiffness for supporting the human trunk. The primary structure consists of a symmetrically distributed chain-type configuration on both sides of the spine, allowing for adjustable stiffness to assist users during complex body movements. In comparison to traditional rigid exoskeletons, this design not only enhances flexibility but also improves overall exoskeleton performance. Kinematic analysis of the exoskeleton reveals a high degree of freedom. Experimental results demonstrate that the exoskeleton provides a wide range of motion, with average ranges of 63° flexion, 33° extension, 25° lateral flexion, and 18° axial rotation when worn.