Assisting immobile individuals with regular repositioning to adjust pressure distribution on key prominences such as the back and buttocks is the most effective measure for preventing pressure ulcers. However, compared to active self-repositioning, passive assisted repositioning results in distinct variations in force distribution on different body parts. This incongruity can affect the comfort of repositioning and potentially lead to a risk of secondary injury, for certain trauma or critically ill patients. Therefore, it is of considerable practical importance to study the passive turning comfort and the optimal turning strategy. Initially, in this study, the load-bearing characteristics of various joints during passive repositioning were examined, and a wedge-shaped airbag configuration was proposed. The airbags coupled layout on the mattress was equivalently represented as a spring-damping system, with essential model parameters determined using experimental techniques. Subsequently, different assisted repositioning strategies were devised by adjusting force application positions and sequences. A human-mattress force-coupled simulation model was developed based on rigid human body structure and equivalent flexible springs. This model provided the force distribution across the primary pressure points on the human body. Finally, assisted repositioning experiments were conducted with 15 participants. The passive repositioning effectiveness and pressure redistribution was validated based on the simulation results, experimental data, and questionnaire responses. Furthermore, the mechanical factors influencing comfort during passive assisted repositioning were elucidated, providing a theoretical foundation for subsequent mattress design and optimization of repositioning strategies.
通过辅助长期卧床人员定时翻身，调整压力分布避免单一部位长时间受压是预防压疮的最有效措施。但被动辅助翻身与人体主动翻身相比，身体各部位受力存在明显差异，可能影响翻身舒适性，甚至对外伤及危重患者造成二次伤害。因此，探究被动翻身舒适性影响因素，确定最优翻身策略具有较大的实用价值。首先，本文研究被动翻身人体各关节承载特征，提出了一种楔形气囊构型，并将床垫楔形气囊对偶布局等效为弹簧-阻尼模型，并基于实验方法进行模型关键参数辨识。然后，通过调整施力位置、顺序，设计了不同辅助翻身策略，建立了基于刚性人体结构与柔性等效弹簧的人-垫力耦合仿真模型，获得了人体主要承压部位受力情况。最后，对15名受试者开展辅助翻身试验，通过分析仿真结果、实验数据及问卷评分，验证了辅助翻身与压力调整效果，阐明了被动翻身过程人体舒适性的力学影响因素，为后续床垫构型设计与辅助翻身策略优化提供了理论基础。.
Keywords: Airbag mattress; Assisted turning; Comfort evaluation; Human-machine coupling modelling; Pressure sore prevention.