A screw propelling capsule robot

This paper presents a novel approach to active capsule robot, traversing in a tubular and compliant environment containing solid-liquid mixture. One of the application fields is active capsule endoscopy intended to navigate inside the gastrointestinal tract for diagnosis and therapy. This robot is driven by a screw impeller, which converts rotation to axial motion in two ways: one is through fluid dynamic pressure with fluid film generated hydrodynamically; the other is through direct contact with the mucosal folds and food residue on the intestinal wall. In this paper, the design and fabrication of the capsule robot are presented in brief. A preliminary theoretical model for the working principle of the robot is built, considering both the hydrodynamic effect and the direct contact. In addition, a series of in vitro tests were carried out with several prototypes to verify the locomotion ability of the robots.