Tracing and localization system for pipeline robot

Two different robotic systems for in-pipe inspection of underground oil pipelines are overviewed. This paper mostly introduces the tracing and localization technology of in-pipe robot without tether cable. The key technique is how to achieve reliable communication between inside and outside of metallic pipeline. In order to solve the shielding effect of metallic pipe-wall, extreme-low-frequency electromagnetic pulse (ELF-EP) is adopted to transmit messages. According to the multiple-satellite measuring principle, pipeline global position system (P-GPS) is proposed serving as long-distance tracing and near-field localization. The design method of compacted communication system with low power consumption is introduced and the communication protocol is made. An effective localization algorithm based on database query is presented. The tracing and localization system is verified with robust solutions during field tests and can be applied to various in-pipe robots for autonomous motion and inspection.