Characteristics of locomotion efficiency of an expanding–extending robotic endoscope in the intestinal environment

Robotic endoscopes with locomotion ability are among the most promising alternatives to traditional endoscopes; the locomotion ability is an important factor when evaluating the performance of the robot. This article describes the research on the characteristics of an expanding–extending robotic endoscope’s locomotion efficiency in real intestine and explores an approach to improve the locomotion ability in this environment. In the article, the robot’s locomotion efficiency was first calculated according to its gait in the gut, and the reasons for step losses were analyzed. Next, dynamical models of the robot and the intestine were built to calculate the step losses caused by failed anchoring and intestinal compression/extension. Based on the models and the calculation results, methods for reducing step losses were proposed. Finally, a series of ex vivo experiments were carried out, and the actual locomotion efficiency of the robot was analyzed on the basis of the theoretical models. In the experiment, on a level platform, the locomotion efficiency of the robot varied between 34.2% and 63.7%; the speed of the robot varied between 0.62 and 1.29 mm/s. The robot’s efficiency when climbing a sloping intestine was also tested and analyzed. The proposed theoretical models and experimental results provide a good reference for improving the design of robotic endoscopy.