Skin injury occurrence estimation model for the wearable robot use and its experimental validation

Abstract

The wearable robot's support delivered to the human wearer induces various types of force and pressure interactions. Continued and repeated interaction of shear stress and normal pressure with human skin under the cuff eventually leads to pain and skin injury. In fact, redness and abrasions corresponding to pressure ulcers(PU) have been reported in real wearable robot use cases. In addition, the authors confirmed cases of similar outbreak of pressure ulcer through interviews with wearable robot users, physicians, and robot makers. However, studies on PU breakout mechanisms related to the use of wearable robots are very rare. Therefore, we developed the skin injury breakout time estimation model in the wearable robot use environment through the comprehensive analysis of PU breakout mechanism in general biomedical circumstances. Three major causes of PU and their relationship with breakout time were identified, and two unmeasurable causes of PU were converted into the measurable skin normal pressure by applying the friction coefficient and FEM analysis of human muscular skeletal tissue. Through this conversion process, it was possible to establish a pressure ulcer breakout time estimation model based on the measurable skin normal pressure. The proposed PU breakout time estimation model was validated through experiments with human subject.