UAV Autonomous Navigation and Safe Trajectory Planning for Transmission Line Voltage Measurement Using Multi-Segment Sub-Conductor Localization

Traditional on-tower inspections and direct voltage testing suffer from low efficiency and high labor intensity. To address this issue, this study proposes an autonomous unmanned aerial vehicle (UAV) heading-positioning algorithm for transmission-line inspection based on multi-segment sub-conductor localization, together with a route-planning method that maintains the minimum safe distance from lines of different voltage levels. The heading-positioning algorithm and the route-planning method were applied to six-bundle 750 kV and eight-bundle 1000 kV transmission lines. The results indicated that, compared with traditional manual tower-climbing operations, the proposed positioning algorithm and the route-planning method increased inspection efficiency by more than 77.8%, improved result repeatability to 95%, and reduced labor intensity by at least 50%. Inspections were completed without tower climbing, substantially enhancing safety.