Pathway selection mechanism of a screw drive in-pipe robot in T-branches

Pipelines are important infrastructures in today's society. To avoid leakages in these pipelines, efficient robotic pipe inspections are required, and to this date, various types of in-pipe robots have been developed. Some of them can select their path at a T-branch at the expense of additional actuators. However, fewer actuators are better in terms of size reduction, energy conservation, production cost, and maintenance. To reduce the number of actuators, a screw drive mechanism with only one actuator has been developed for propelling an in-pipe robot through straight pipes and elbow pipes. Based on this screw drive mechanism, in this paper, we develop a novel robot that uses only two motors and can select pathways. The robot has three locomotion modes: screw driving, steering, and rolling modes. These modes enable the robot to navigate not only through straight pipes but also elbow pipes and T-branches. We performed experiments to verify the validity of the proposed mechanism.