This work presents a construction of a novel system for autonomous inspection of power transmission lines using a quadrotor
helicopter. The aircraft follows the power lines at a constant distance and acquires high-resolution images of the conductors,
dampers, and towers. Monitoring of the vegetation under the power lines is also performed. The traditional inspection is carried
out by helicopters equipped with high-resolution cameras or by direct visual examination by personnel climbing over de-energized
power lines. However, visual inspection is time-consuming, labor-intensive, and dangerous, and often, helicopter cameras cannot
capture the acute details needed for accurate and comprehensive examinations. This work successfully evaluates a mathematical
model for the quadrotor helicopter used in autonomous inspection through simulations and flight experiments. Two control
strategies for power line tracking are compared: a classical PID and a fuzzy PD control. Several simulations and experimental
results confirm the efficiency of both control laws, but the fuzzy controller performs better under strong wind disturbances. The
results of this work will be implemented by an electric power company to inspect electrical transmission facilities regularly.
