In-pipe Robot with Capability of Self Stabilization andAccurate Pipe Surface Cleaning

Luis A. Mateos and Markus Vincze

Abstract— After 50 years the connections between fresh waterpipes (800-1000mm diameter) need to be repaired due to agingand dissolution of the filling material. Only in Vienna 3000kmof pipes need to be improved, which requires a robotic solution.The main challenge is to accurate place the robot in thecenter of the pipe while overcoming the push back forces andvibrations caused in the cleaning process, so that the cleaningtool is able to focus on desired area of the pipe surface. Thispaper presents the overall design of an in-pipe cleaning robotDeWaLoP, which includes a suspension system to position itselfas a rigid structure stably in the center of the pipe, while the Hconfiguration of the robot arm is able to stabilize the cleaningtool in the cleaning process, to reduce the vibration and pushback forces.

I. INTRODUCTION

Fresh water pipelines are prone to damages due to aging,excessive traffic and geological changes. Resulting fromthese damages, the pipe-joints may not be completely her-metic and water loss along the pipeline may occur. Leakageis not only a problem in terms of wasting an importantresource, it also results in an economic loss in form ofdamages to the supplying system and to foundations of roadsand buildings too [1] [2].

The installation or replacement of pipelines implicateshigh cost and use of heavy machinery, such as cranes. Inaddition, side effects may occur, such as constructions sitesplaced along streets, blocking pedestrian and traffic tracks[3]. The size of pipes transporting water between residentialareas and industrial parks is normally ranged from 800mmto 1200mm in diameter, which make it possible for one manto enter. Consequently, human operators can access the pipeand attempt to clean and repair it, as shown in figure 1.Nevertheless, this creates a special situation that presentssafety and health risk to the human operator [4]. Currently,the applications of robots for the maintenance of the pipelineutilities are considered as one of the most attractive solutionsavailable. Nevertheless, to substitute skilled human operators,pipe redevelopment requires mechanisms with high degreeof mobility, able to move along the pipeline, overcomingobstacles, extreme environments, and with high accuracyclean and repair specific areas of the pipe [5] [6] [7].

The most common method to clean the pipe is using waterjet, as this method does not require accurate positioning ofthe robot inside the pipe. However, the water pressure hasdisadvantage of damaging the pipe-joint hemp pack which

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} atacin.tuwien.ac.at

is caulked up with a lead ring. Thus, we adopt a cleaningmethod which is using wire brushes disks and grinding headsto remove the corrosion of the pipe by friction. By autosuspension system, our robot is able to fix its in-pipe positionaccurately to support the cleaning tool system to focus onspecific areas.

II. RELATED WORK

In-pipe cleaning robots can be categorized to two types:1) Pressure-based cleaning robots and 2) Tool-based cleaningrobots. In this section, we present the typical in-pipe cleaningrobots developed both from academia and industry.

A. Pressure-based cleaning methods

J. Saenz [8] presents a cleaning system able to workefficiently and control the pressure of the nozzle througha relative accurate positioning to the pipe wall. They com-mented ”A common risk when cleaning with high pressurewater is the possible damage to the surface from overlyapplied pressure. This risk can be minimized with such acleaning system where the cleaning parameters can be care-fully controlled and monitored”. Even if the pressure can becontrolled, for cleaning pipe-joint this is not recommended,due to the pressure exerted by the water, pushing the hermeticseal of the pipe-joint.

B. Tool-based cleaning - Impact abrasion methods

1) GRISLEE - Gasmain Repair and Inspection System forLive Entry Environments: The GRISLEE is designed to bemodular, so different kinds of in situ repairs are possible.The cleaning system consists of flails, which expand whenrotates and cleans the surface by impact abrasion method.The system has a compact size, and is able to work indifferent pipe sizes [9].

2) Umbrella mechanism: The umbrella mechanism con-sists of a structure able to increase its height in order to adaptto different pipe diameters. The cleaning system is similar toan umbrella kind open-and-close mechanism, which makesthe robot highly adaptable to different pipe sizes [10].

Commercial cleaning system such as Robocutter [11],KASRO robot [12], OptiCut [13] and IMS Turbo cutter [14]are smaller robots but use similar design like the umbrellamechanism. Lacking of stability, due to the push back effectsand vibration caused in the cleaning process.

C. Tool-based cleaning - Cutting methods

1) Cutter cleaner arm: N. T. Thinh [15] describes an in-pipe robot for cleaning and inspecting, in which the cleaning

Fig. 1. Human operator inside the pipe, cleaning the pipe wall with an angle grinder - cutting disk (left). DeWaLoP robot fixed inside the pipe, creatinga rigid structure from its six wheeled-legs, cleaning with an angle grinder - wire brushes disk (right).

mechanism is an arm consisting of small cutting plates. Thearm is located on the front of the robot, perpendicular tothe pipe’s horizontal with the same length as the inner-pipe’s diameter. From this configuration, the cleaning methodconsists of rotating the arm, milling all corrosion while therobot moves inside the pipe. Although the mechanism is ableto remove strongly incrusted corrosion. The drawback of thisconfiguration is the low flexibility of the cleaning tool to pipedisplacement. In other words, the cleaning mechanism willdamage the pipe if the pipes are not perfectly aligned.

C. D. Jung [16] proposes an in-pipe cleaning robot withthe 6-link sliding mechanism which can be adjusted to fitinto the inner face of the pipe using pneumatic pressure. Theproposed in-pipe cleaning robot have self forward/backwardmovement as well as rotation movement of brush. However,the disk cleans all over the in-pipe wall without being ableto focus on a specific area.

In contrast to the state-of-the-art cleaning mechanisms,DeWaLoP in-pipe robot is able to fix itself stably in a specificlocation using self suspension system. Independently fromthe main body of the robot, the cleaning tool is flexiblyconfigured which can be adjusted in a cylindrical 3D space,able to move up to 100mm in the pipe’s horizontal axis, andreach to the surface of the pipe with diameter in the rangeof 800mm to 1000mm.

Besides its high positioning capability and flexibility, thecleaning mechanism is able to overcome vibrations and jumpback forces from the cleaning tool with its integrated sus-pension system, mimicking the reaction of a human operatorwhen such events happens.

ACKNOWLEDGMENT

This work is part-financed by Project DeWaLoP fromthe European Regional Development Fund, Cross- BorderCooperation Programme Slovakia- Austria 2007-2013.

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