Towards unmanned aerial vehicle-deployed pulsed eddy current for NDT

Oil and gas transmission pipelines play a key role in modern society. Accumulation of damage over time can deteriorate the interior and exterior of steel pipes and lead to dramatic economic losses or life-threatening accidents. Hence, periodical local wall thinning measurement must be conducted to ensure structural integrity throughout their expected lifetime. Unmanned Aerial Vehicles (UAVs) with high-resolution cameras may conduct remote screening where manual inspection is impractical, reducing human risk exposure and improving operational efficiency However, this photogrammetric inspection cannot detect discontinuities beneath exterior surface coatings. Consequently, limited UAV-based close-proximity pipeline inspection is observed in current industrial practice.
This body of work introduces a Pulsed Eddy Current (PEC) system deployed autonomously from a UAV to offer non-intrusive sub-surface inspection. The operating principles of the sensor architecture, as well as a light-weight sensor design suitable for inspection of wall thinning of steel pipelines, are discussed. In laboratory testing, PEC has been deployed from a robotic manipulator to characterise its performance and sensitivity in pose-variable aerial deployment scenarios. These results inform system design and deployment of such a sensing modality from a multirotor platform, supporting detailed and accurate asset evaluations by a UAV agent in a raster scanning aerial inspection process.