  Autonomous inspection of powerlines with quadrotors is challenging. Flights
require persistent perception to keep a close look at the lines. We propose a
method that uses event cameras to robustly track powerlines. Event cameras are
inherently robust to motion blur, have low latency, and high dynamic range.
Such properties are advantageous for autonomous inspection of powerlines with
drones, where fast motions and challenging illumination conditions are
ordinary. Our method identifies lines in the stream of events by detecting
planes in the spatio-temporal signal, and tracks them through time. The
implementation runs onboard and is capable of detecting multiple distinct lines
in real time with rates of up to $320$ thousand events per second. The
performance is evaluated in real-world flights along a powerline. The tracker
is able to persistently track the powerlines, with a mean lifetime of the line
$10\times$ longer than existing approaches.
