Development of an in-pipe robot with two steerable driving wheels

This paper presents a novel in-pipe robot with two helix-angle-adjustable driving wheels. The robot is designed based on the concept of triangular crossing section, which solves the geometric constraint problems of the elbow pipe and the T-branch with the avoidance of destroying the robot system. It consists of a driving mechanism, a supporting device and a central axis. The driving mechanism is driven by two DC motors, which are respectively used for the adjustment of the helix angle and the rotation of the two driving wheels. The supporting device is composed of four synchronous four-bar linkage groups, which are used to improve the system stability, obstacle-crossing ability and the adaptability to pipes in different diameters. By controlling the helix angle of the driving wheels, the robot can adapt to different pipeline environments with three locomotion modes: double helix mode in vertical pipes, rectilinear mode in horizontal pipes and steering mode in elbow pipes and T-branches. Experiments were performed to verify the strong adaptability of the robot in different pipeline environments and its good traveling capability in elbow pipes and T-branches.