Characteristics of a Pneumatic Bellows Actuator for Colonoscopy

Abstract

Since colonoscopic insertion requires a high level of skill on the part of the examining physician, the patient may experience pain if the physician is not so highly skilled. In this study, our objective is to realize an easy-to-execute endoscopic insertion that does not rely on the physician’s skill. We develop a pneumatic actuator that gives the endoscope self-propulsion capability. The actuator is configured with three bellows made of polyethylene film. By applying pneumatic pressure to the bellows in a specific sequence to extend and contract them, the end of the actuator moves elliptically. Thus, the endoscope can be given propulsion performance by attaching several actuators and driving them in different phases. In this paper, the basic characteristics of the actuator are determined geometrically from the characteristics of the bellows, and then those characteristics are compared to the results of experiments. In addition, experiments are conducted in which a rod, used as a dummy endoscope, is transported through a pipe and inserted in an intestinal tract model. The experiments confirm and validate the proposed concept.