Automatic In-pipe Robot Centering from 3D to 2D Controller Simplification Luis A. Mateos, Marcos Rodriguez y Dominguez and Markus Vincze Abstract— After 50 years the connections between fresh water pipes (800-1200mm diameter) need to be repaired due to aging and dissolution of the filling material. Only in Vienna 3000km of pipes need to be improved, which requires a robotic solution. The main challenge is to accurately align the robot axis with the pipe axis to enable the rotary motion of the maintenance tool. The tool system for cleaning and sealing is mounted on the maintenance unit of the robot consisting of six wheeled- legs. These legs extend to the irregular cast-iron pipe and set the robot structure eccentric to the pipe ′ s center. In order to center the maintenance unit, distance sensors on the legs allow to adapt to the noncircular shape of the pipe. Correcting the leg extension allows to obtain better positioning of the cleaning tool. I. INTRODUCTION Fresh water pipelines are prone to damage due to aging, excessive traffic and geological changes. Resulting from these damages, the pipe-joints may not be completely her- metic and water loss along the pipeline may occur. Leakage is not only a problem in terms of wasting an important resource, it also results in an economic loss in form of damages to the supplying system and to foundations of roads and buildings too [1] [2]. The installation or replacement of pipelines implicates high cost and use of heavy machinery, such as cranes. In addition, side effects may occur, such as constructions sites placed along streets, blocking pedestrian and traffic tracks [3]. The size of pipes transporting water between residential areas and industrial parks is normally ranged from 800mm to 1200mm in diameter, which make it possible for one man to enter. Consequently, human operators can access the pipe and attempt to clean and repair it, as shown in figure 2. Nevertheless, this creates a special situation that presents safety and health risk to the human operator [4]. Currently, the applications of robots for the maintenance of the pipeline utilities are considered as one of the most attractive solutions available. Hence, to substitute skilled human operators, pipe redevelopment requires mechanisms with high degree of mobility, able to move along the pipeline, overcoming obstacles, extreme environments, and with high accuracy clean and repair specific areas of the pipe [5] [6] [7]. Before cleaning or sealing the pipe, as prerequisite, the robot must be set perfectly to the pipe center. Otherwise, the movement of the tool mechanism (cleaning and sealing) Luis A. Mateos and Markus Vincze are with Automation and Con- trol Institute (ACIN), Vienna University of Technology (TU WIEN), Gusshausstrasse 27 - 29 / E376, A - 1040, Austria. {mateos,vincze} at acin.tuwien.ac.at {marcos.rodriguezyd} at gmail.com Fig. 1. DeWaLoP -Developing Water Loss Prevention in-pipe robot. The robot is set as a rigid structure inside pipe by extending its wheeled-legs so the tool mechanism on its front (cleaning and sealing) work by rotating from the robot central axis. However, each leg extend differently due to corrosion structures over the pipe wall and to center the robot inside the pipe a 3D controller is required, to take into account all 6 wheeled-legs feedback potentiometer. may required to be adjusted all the time, making the system more susceptible to damage the pipe while cleaning as well as slowing the redevelopment process. However, placing the in-pipe robot precisely to the pipe center is considered a difficult task. Pipes in reality suffer from corrosion and other damages, which bring them into non-circular shapes. Their distorted circular shape can not be pre-measured, therefore robots need to adjust their position according to the eccentricity of the pipes while cleaning and sealing. This paper presents an overview design of the DeWaLoP robot and its multi functionality, with special focusing on its ability to automatically self-sitting in the center of the pipe, which has distorted its circular surface. In the experimental evaluation section, a prototype robot will be tested and statistic results will be given. II. RELATED WORK DeWaLoP robot must be fixed inside the pipe, in order to overcome jump backs and vibrations from the power cleaning tools (around 1500 Watts). Thus, to handle these amount of forces the structure must be rigid and stable. Therefore, DeWaLoP robot is able to perform multiple tasks, such as inspecting the pipe with its video system, while cleaning the pipe and sealing the pipe with an injection system, thanks to the automatic self centralizing solution. Most of them do not require to set the robot as a rigid 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) November 3-7, 2013. Tokyo, Japan 978-1-4673-6358-7/13/$31.00 ©2013 IEEE 258