Human-Machine Compatibility of the Elbow Exoskeleton Robot Axis Misalignment Problem and Compensation Mechanism

With the increasing burden of neurological diseases and the aging population, the need for efficient upper limb rehabilitation is becoming increasingly urgent. The elbow exoskeleton can provide high-intensity, quantifiable repetitive training, but it is limited by human-machine compatibility, especially the misalignment of the mechanical and physiological axes. This paper systematically reviews the axial misalignment problems and compensation mechanisms of elbow exoskeletons, and sorts out the characteristics and alignment difficulties of rigid, flexible, and hybrid structures. This paper analyzes the biomechanical causes of translation, angle, and comprehensive dislocation, and discusses their effects on additional load, movement smoothness, and long-term comfort. In addition, this paper focuses on summarizing compensation strategies such as mechanical passive self-alignment, series elastic drive, soft self-compliance, neuro-electromyographic intelligent control, intelligent compensation control mechanism, adjustable geometric structure, and compares their advantages and disadvantages as well as applicable scenarios. Finally, this paper proposes that intelligent adaptive axis alignment, rigid-flex hybrid bionic structure, individualized human-machine interface, and unified evaluation system should be developed in the future to provide a reference for the design of a high-level human-machine fusion elbow exoskeleton.