Modelling, analysis and experiments of a screw propelling capsule robot

Active locomotion has been a challenge in the research and development of capsule endoscopies for diagnosis and therapy inside gastrointestinal tracts. As one prospective solution to the active locomotion of capsule robots, screw propelling has many important issues to be addressed in both theory and practice. In this paper, we build one- and two-dimensional models of screw propelling and make quantitative analysis to find the relationship between the axial thrust force and the geometric parameters of the screws, for optimal design of the actuation mechanism with high efficiency of propulsion. A few prototypes of the capsule robots are developed and a series of contrast experiments are conducted to verify the theoretical models and analysis. The effectiveness of active drive of capsule robots by screw propelling has been preliminarily shown by the experiments with the prototypes crawling in a tube.