Abstract
We have many small diameter pipes that are cooling pipes for atomic power stations, boiler pipes, and gas or water pipe lines. They must be periodically inspected in order to protect the accident previously. Diameters of these pipes are different at the place where pipes change from the main to the branch and a step comes here. The inspection robot for these pipes must move different diameter and go over the step. We propose a mobile robot that imitates the moving of a green caterpillar. The robot is constructed by the eight parallel rubber bellows and three suction brakes. The fabricated mobile robot was confirmed to move in different diameter pipes whose diameters are more than 70 mm. Its speed was 16 mm/s.
