Abstract: By using only one pneumatic line, an inchworm-like micro robot for pipe inspection is invented. Based on drilling different micro holes among the three chambers, the timing of the airflow can be controlled within the chambers. The rear clamp, the elongation module, and the front clamp work sequentially as the air flows into each chamber. It enables the robot not only to generate inchworm-like locomotion, but also to allow for a significant reduction in both the stiffness of pneumatic lines and the friction force caused by one pneumatic line. In addition, it is possible to fabricate a micro robot with diameter of 10 mm since it does not need extra pneumatic lines to connect chambers. In order to operate the robot efficiently, the stroke corresponding to the supplied pressure is theoretically analysed with various sizes of holes between the rear clamp and the elongation module and it is compared to the stroke of the experimental results. Based on these results, maximum velocity was obtained by tuning the air insufflation time under the in-pipe conditions. Finally, the adoptability of the robot was tested under a variation of pipe diameters.
