Research on transmission line positioning method based on magnetic gradient tensor

To address the problem of real-time dynamic identification and precise positioning of transmission lines faced by unmanned aerial vehicles (UAVs) during autonomous inspection along transmission corridors, this paper proposes a magnetic field source localization method based on the magnetic gradient tensor. In this method, the magnetic field distribution of the local area around the transmission line is obtained in real time using a UAV equipped with a high-precision magnetic field measurement device, and a cross-shaped magnetic gradient tensor measurement array with a central sensor is constructed. The magnetic gradient tensor T is derived using a finite-difference scheme, and its intrinsic structure is further analyzed so that the spatial distance and geometric direction of the transmission line relative to the sensor can be inverted. Experiments show that the distance positioning deviation does not exceed 5%, and the direction positioning deviation does not exceed 2°. This method therefore provides a technical path with high robustness and engineering feasibility for intelligent UAV inspections of transmission lines in complex environments.