  We present a fully autonomous self-recharging drone system capable of
long-duration sustained operations near powerlines. The drone is equipped with
a robust onboard perception and navigation system that enables it to locate
powerlines and approach them for landing. A passively actuated gripping
mechanism grasps the powerline cable during landing after which a control
circuit regulates the magnetic field inside a split-core current transformer to
provide sufficient holding force as well as battery recharging. The system is
evaluated in an active outdoor three-phase powerline environment. We
demonstrate multiple contiguous hours of fully autonomous uninterrupted drone
operations composed of several cycles of flying, landing, recharging, and
takeoff, validating the capability of extended, essentially unlimited,
operational endurance.
