Abstract: A screw drive robot equipped with only one DC motor and a solenoid is proposed for in-pipe inspection task, which has axial and circum-directional inspection ability. The robot is based on a constraint mechanism which only needs one DC motor and a solenoid. The developed platform which carries a CCD camera and provides the robot with stable axial inspection ability is also investigated. By controlling the motor and the solenoid to work or not, the force constraints acting on the robot change correspondingly. The robot thus has two working modes: under the driving mode the robot propels itself in the pipe, and it will check the defects of the pipe under the detecting mode. By switching these two working modes, the robot can perform the pipeline inspection task. Finally, experiments are conducted to testify the mobility and the inspecting ability of the robot.

Key words: Axial and circum-directional inspection, In-pipe robot, Screw drive, Variable constraint mechanism