Basic Study on a Peristaltic Motion-Type In-Pipe Inspection Robot Using a Hyper-Extension Unit for Improving Locomotion Speed

This paper proposes a peristaltic motion-type in-pipe inspection robot with a hyper-extension unit in the front part, to inspect small-diameter and long-distance pipes. This study aims to inspect long, narrow, and complex pipes. In conventional in-pipe inspection robots with a simple structure, it has been difficult to increase both the pull-in force of the traction wiring and the push-in force of the robot’s head when passing through the bending pipe. Therefore, this paper proposed a peristaltic motion-type in-pipe inspection robot with a hyper-extension unit in the front of the robot, which can extend 294% even at low expansion rates. This robot operates in two distinct patterns: an inchworm-earthworm pattern that can exert large traction and an inchworm pattern that can operate at high speed under low loads. To verify the effect of changing the above two patterns on the inspection speed, horizontal straight pipe movement experiments were conducted by varying the applied traction. The speed of the inchworm pattern is 12.01 mm/s, and that of the inchworm-earthworm pattern is 3.43 mm/s without load. By contrast, the speed of the inchworm pattern is 1.28 mm/s, and that of the inchworm-earthworm pattern is 1.94 mm/s with the load. These results show that the proposed robot can effectively inspect pipes with various movement patterns, adapting to the traction exerted on the wiring.