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. The inspection robot for these pipes must move different diameter. We propose a mobile robot that can surely move in a pipe whose diameter changes. The robot is constructed by the three rubber bellows as pneumatic actuator, seven electromagnetic valves and four suctional brakes. The fabricated mobile robot was confirmed to move in different diameter pipes whose diameters are between 90 mm and 150 mm. Its speed was 21 mm/s.
