Abstract: This study investigates the friction and deformation behavior of the skin in contact with a rigid massage ball and its infuencing factors. Pressing and stretching experiments were conducted using a collaborative robot experimental platform. The experiments encompassed a loading normal force range of 2 N to 18 N and a sliding speed range of 10 mm/s to 20 mm/s. The friction response curve exhibits two diferent stages: static stick state and dynamic stick-slip stage, both of which have been mathematically modeled. By analyzing the experimental data, we analyzed the efects of elastic modulus, sliding speed and normal loading force on skin tangential friction and tensile deformation. The results indicate that as the normal load increases, both friction and deformation exhibit an increase. Conversely, they decrease with an increase in elastic modulus. Notably, while deformation diminishes with higher sliding speed, friction force remains relatively unafected by velocity. This observation can be attributed to the strain rate sensitivity resulting from the viscoelastic characteristics of the skin under substantial deformation. This study advances the understanding of friction and deformation behavior during skin friction, ofering valuable insights to enhance the operational comfort of massage robots.

Key words: Human skin , · Friction sliding , · Deformation , · Robotic massage , · Stereo image