Guardians of the Grid

The arteries of the modern world, electrical transmission lines carry the lifeblood of our technological society — power. Ensuring that they are operating normally is of paramount importance, and that is why regular inspections of power lines are so important.

Inspections of these lines are vital for several reasons. Faulty components, vegetation encroachment, and weather damage can all compromise the integrity of the lines, leading to outages, power quality issues, and even fires. Early detection of these problems through inspections allows for timely repairs and preventive maintenance, minimizing disruptions and safeguarding public safety.

However, inspecting vast stretches of power lines, often snaking through remote and rugged landscapes, poses significant challenges. Traditional methods like foot patrols and manned helicopters are labor-intensive, time-consuming, and expose personnel to potential hazards. Dense vegetation, steep terrain, and harsh weather conditions can further impede physical access, leaving critical sections inadequately monitored.

Thankfully, technological advancements are transforming the landscape of transmission line inspection. Unmanned aerial vehicles (UAVs), or drones, equipped with high-resolution cameras and LiDAR sensors, are increasingly deployed to navigate treacherous terrains and capture detailed images of the lines. These aerial inspections are faster, safer, and more comprehensive, providing inspectors with a bird's-eye view of potential trouble spots.

The unique environment, and especially the magnetic field interferences, found in close proximity to electrical transmission lines make the job difficult for UAVs, however. To prevent these factors from wreaking havoc on the drone’s onboard control system and other electronics, specialized — and very expensive — equipment is needed. Those costs limit how widely these systems can be deployed at present.

Fortunately, that may change in the near future as a result of the work done by a team of researchers at Chiba University in Japan. They have developed a low-cost system for the aerial inspection of power lines. This feat was achieved by using less expensive hardware that, by itself, is not especially well-suited for the environment it is to operate in. Custom algorithms were then developed to correct for the sources of error that are introduced by magnetic field interference. The result is a low-cost platform that could enable the widespread adoption of automated aerial inspection systems.

The team’s innovation requires a drone to be equipped with only a global navigation satellite system (GNSS) receiver, RGB camera, and a millimeter wave radar unit. To keep the vehicle flying close to the power lines without pricey components, a Hough transform is used to process images captured by the camera and provide an estimate of its distance from the line. Another algorithm locates the start and end of the line and uses that information to keep the UAV on heading in spite of electromagnetic interference experienced by the onboard compass.

Additional software control modules were included to keep the vehicle on course as it drifts due to the low accuracy of the GNSS receiver. Furthermore, a controller was added to account for unpredictable factors, like gusts of wind, to prevent the drone from losing its way.

A UAV equipped with the researcher’s hardware design and custom algorithms was tasked with inspecting a power line carrying 10 kV of electricity. It was found that the algorithms were sufficient to keep the vehicle on track, but unexpected gusts of wind did cause some challenges. The team plans to continue to improve their methods to address this issue with the hope that UAVs powered by their system will soon allow for more thorough inspections of electrical transmission lines.