Background Pressure ulcer is a typical disease, which is common in long-term bedridden patients and difficult to cure. It is necessary to study the biomechanics of the typical sites of pressure ulcers in turning over from supine position, which is an important reference for clinical medical nursing and and guides an assisted exoskeleton robot design. Methods The typical sites of pressure ulcers mainly focus on the scapula and the hip-sacrum of the trunk in turning over from the supine position.

more »

... Based on the requirements of rehabilitation technical aids and the anatomy theory, the simple model of the scapula and the hip-sacrum were established for a force analysis in the process of turning over from the supine position, and the theoretical contact pressure between the human body and the bed surface was obtained. Then, three-dimensional models of the scapula and hip- sacrum were reconstructed and the maximum stress under different boundary conditions was obtained by finite element analysis. Finally, the pressure distribution sensor was used to carry out the human experiment of turning over from the supine position, and the pressure cloud diagram and the maximum contact pressure curve of the shoulder blade and the hip were obtained under different angles of turning over. Results The results from theoretical analysis, simulation and experiment were almost the same change trends, and the curves and the stress diagrams showed the contact pressure change of the typical sites of pressure ulcers in turning over. The angle threshold of the optimal comprehensive pressure can improve the use efficiency of the equipment to assist human turning over and reduce the incidence of pressure ulcers in the use of assisted bed in long-term bedridden patients. Conclusions In response to the less research on the mechanism of pressure ulcer, biomechanical changes have been revealed, which helps to explain the causes of pressure ulcer disease and provide basis for improving clinical nursing, and the relevant results provided a reference that contributes to the man-machine coupling design of the assisted rollover robot.