Cured-in-place pipe rehabilitation is one of the most widely used trenchless renewal methods for buried pipelines. Installation of a CIPP liner results in a tight fit within the host pipe, but meanwhile, the lateral connections are also covered. Therefore, various manually operated cutters are designed to reopen the lateral connections. However, even with the help of the cutters, manual operation is still tedious and inefficient. Hence, a cutting robot capable of automatically reopening the lateral connections has great commercial prospects and significance.

In this thesis, an automatic cutting robot, designed for reopening the lateral connections, is developed from an existing robotic cutter. Three main problems should be solved: lateral connection recognition, robot localization, and...[ Read more ]

Cured-in-place pipe rehabilitation is one of the most widely used trenchless renewal methods for buried pipelines. Installation of a CIPP liner results in a tight fit within the host pipe, but meanwhile, the lateral connections are also covered. Therefore, various manually operated cutters are designed to reopen the lateral connections. However, even with the help of the cutters, manual operation is still tedious and inefficient. Hence, a cutting robot capable of automatically reopening the lateral connections has great commercial prospects and significance.

In this thesis, an automatic cutting robot, designed for reopening the lateral connections, is developed from an existing robotic cutter. Three main problems should be solved: lateral connection recognition, robot localization, and robot arm control. Firstly, vision is used to recognize the lateral connection. Specifically, an image processing method is proposed to extract the lateral connection from the captured images. Secondly, for robot localization and control, two lasers which project two spots onto the pipe are mounted on the robot. According to the relative position between the center of the two laser spots and the center of the lateral connection, the robot can be localized. Moreover, PID controllers are designed for controlling the motion of the robot and its arm with the pixel distance between the two centers as the errors. In addition, a laser-based distance measurement method is proposed to measure the distance between the drill and the lateral connection. Also, on the basis of this approach, a distance measurement method based on image geometry is proposed.

Based on the developed cutting robot, various experiments are implemented. The experimental results show that the lateral connection can be effectively recognized by using the proposed method, and the end-effector can accurately move to the desired position.

Key words: CIPP rehabilitation, robot vision, recognition, localization, distance measurement.