Soft Tissue Bruise Injury by Blunt Impact in Human-Robot Interaction - Difference of Tolerance between Chest and Extremities

To obtain information on the mechanical tolerance of soft tissue bruise injury caused by dynamic contact between human body parts and a robot, impact tests were conducted using anesthetized live pigs. A falling-weight impact tester was used to conduct tests on the chest and extremities by varying the mass and dropping height of the impactor. The subcutaneous tissues of the impacted parts were sampled, and internal bleeding, as a sign of bruising, was pathologically observed. The minimum value of transferred energy per unit area, categorized as a mechanical tolerance value for bruising, was found to be significantly smaller in the extremities as compared to the chest owing to structural differences between the two parts. These structural differences should be carefully considered for safe robot designs.