Frictional Resistance Model of Capsule Endoscope in the Intestine

To optimize the capsule endoscope structure and realize harm-free diagnosis, the small intestine of a pig is used as a research subject in the paper, with the five-element viscoelastic model of intestine adopted as the theoretical basis. In this paper, the intestinal peristalsis is taken into consideration in establishing the mechanical model of capsule endoscope inside the intestinal tract, which simplifies the intestinal peristalsis into sine wave, and thus, the frictional resistance formula is deduced, which covers parameters of radius and length of capsule endoscope, the amplitude and wavelength of peristaltic wave, intestinal elastic modulus and viscosity, and capsule movement velocity and weight, etc. The simulation calculation reveals that (1) frictional resistance grows with the increase in the radius, length and velocity of capsule endoscope and frictional resistance from gravity can nearly be ignored, which are in consistent with the experimental results; (2) when intestinal peristalsis is taken into account, frictional resistance is larger, with more obvious influence arising from the radius, length, movement speed and contact angle of the capsule; and (3) the amplitude rather than wavelength of the peristaltic wave produces greater effect on the frictional resistance.