Unmanned aircraft systems – more popularly known as drones – have emerged
as a novel method of inspecting power lines, allowing power utility
companies to review the health of their infrastructure more quickly and
more safely. But drone operators must maintain a delicate balance, flying
close enough to power lines to capture highly detailed images while staying
far enough away so as not to be affected by the electromagnetic fields
generated by power lines, which interfere with drone operations.
New research from Drexel’s College of Engineering may help shift that
balance. In a presentation to the 2023 IEEE Transportation Electrification Conference & Expo, Fei Lu, PhD, assistant professor of electrical and
computer engineering (ECE) and Gary Friedman, PhD, professor of ECE, along
with collaborators from the University of North Dakota and University of
Kansas, quantified the effect that magnetic fields have on drones and
offered insight on potential solutions.
The researchers tested a DJI Mavic Pro 2 drone under simulated power line
conditions. They sent electricity through large coils to generate magnetic
fields similar to those around real-world power lines. The drone was flown
at varying distances from the coils while they were energized with
different AC current levels.
The tests found that the magnetometer sensors, which work with the
accelerometers and gyroscopes to help the drone position itself in the air,
were significantly impacted.
"The sensor becomes saturated by the strong magnetic fields, meaning that
the signal is larger than their range can measure,” Lu explained. “The
drone's flight control system sends out warnings to the drone operator
about this problem, which is good for protecting the drone but effectively
limits how close the drone can get.”
The research was funded by the Federal Aviation Administration's (FAA)
Center of Excellence for Unmanned Aircraft Systems, which was looking for
insight into the number of drone accidents that occur during power line
“The navigation difficulties caused by the magnetic fields can sometimes
cause drones to crash, causing damage to, at minimum, the drones themselves
but also potentially to power infrastructure,” Lu said.
To mitigate the effects of the magnetic fields, the research team proposed
solutions like sensor shielding, which could protect the magnetometer, or
using sensor fusion methods, which combine data from multiple sensors to
provide redundant and accurate navigation information.
"If one sensor (for example, magnetometer) fails, the other sensor can
still help the flight control," Lu explained.
The research provides valuable insights that can help enable the safe and
effective use of drones for inspecting vital infrastructure, as their
utilization continues to grow. Lu emphasized the importance of continuing
to refine drone technologies as more applications emerge across various
"As researchers, we want to make sure these systems operate reliably and
safely, especially as they are increasingly relied upon to monitor critical
systems like power grids and transportation networks," Lu said. "It's
crucial that engineers understand environmental factors like magnetic
fields and design appropriate navigation techniques. Our work helps move us
in that direction.