Criteria for Classification of in-Pipe Robots

Abstract

In-pipe robots are developed for solving a diverse set of tasks, all of which have to do with monitoring and repairs of pipelines. These tasks include generation of maps of pipelines, detecting defects, anomalies and matter deposits on the inner surface of the pipe, studying the inner surface of the pipe in order to determine if it needs to be repaired and if it is possible to repair it, gathering information on the properties of the inner surface of the pipe and studying the change of these properties. These tasks have practical significance and their automation with robots is economically beneficial. Considering the variety of the existing in-pipe robot designs, it is important to have a way to categorize them and have a clear understanding which tasks are suitable for particular in-pipe robots. To this end, the detailed classifications of in-pipe robots can be used. This paper presents a survey of classifications of in-pipe robots. The previously proposed criteria for such classifications are discussed. The ambiguity of the commonly used classifications is highlighted. The paper presents a more detailed classification, based on eight criteria: 1) types of pipe surfaces that a robot can interact with, 2) controllability of a robot (distinguishing fully passive and active robots), 3) type of contact interaction with the inner surface of the pipe, 4) controllability of normal reactions and 5) controllability of friction forces in contact points or surfaces, 6) contact element types, 7) motor type, 8) transmission type. Combination of these criteria allows highlighting particular features of the existing in-pipe robot designs, simplifying the analysis of problem range that the robot can solve.