Distributed Deployment With Multiple Moving Robots for Long Distance Complex Pipe Inspection

In this study, we propose a method to reduce the traveling load by designing a distributed robot arrangement that considers the shape of a pipeline for a cabled in-pipe mobile robot. The objective of this study is to establish a method to reduce the friction acting on the wires of a self-propelled in-pipe mobile robot and develop a robotic system that can inspect long-distance pipes. This study contributes the purpose of this research in that it proposes a model for estimating the tension acting on the wires of a mobile robot in a pipe and describes a method for reducing the traveling load using a distributed arrangement of robots. The friction acting on the wires in the bent pipe becomes a load for the robots moving in the pipe while towing the wires. Therefore, it is difficult for these robots to inspect complex, long-distance pipelines. Furthermore, we clarified the factors that cause friction forces in long-distance pipes and modeled and quantified the friction forces acting on the wires in the pipes so that each factor could be addressed. Using this model, we propose a distributed deployment method, in which multiple mobile robots are deployed. By driving two robots separated by a distance, we confirmed that two robots could move at 2.5 mm/s in a pipeline that could not be moved by a single robot. Moreover, we proposed a method for controlling the robot according to the load acting on it and confirmed that the robot equipped with this control could inspect a narrow pipe with an inner diameter of 108 mm, where a load of approximately 340 N acted on the back end of the robot, with an efficiency that was approximately 1.7 times higher. This result has the potential to enable the configuration and control of robots, which would be difficult to achieve using conventional methods.