Vibration-Induced Frictional Reduction in Miniature Intracorporeal Robots

The locomotion of miniature medical robots in the interior of the human body, possibly in contact with the tissue of organs and vessels, is a challenging problem in robotics, which, if properly addressed, might favorably impact several significant applications. This paper investigates the potential of employing relatively low-frequency vibrations, generated by an on-board eccentric motor, to reduce friction for such robots, moving by some other primary mechanism over and in contact with liver tissue. This study focuses on the computational modeling and the experimental assessment of the interaction between vibratory-actuated miniature robots and compliant tissue. The computational model developed to analyze the effect of such vibrations, for a robot moving over a substrate with normal-wise viscoelasticity, is employing a modified Dahl model with viscous damping for the tangential friction. Experiments with a vibratory-actuated platform pulled over ex-vivo bovine liver tissue indicate that the friction reduces as the frequency of vibrations increases, in a manner consistent with the model's predictions, reaching a reduction of up to 40%.