6 February/March 2024 | Uncrewed Systems Technology Mission-critical info for uncrewed systems professionals Platform one Researchers in Japan have developed a low-cost UAV for inspecting transmission lines (writes Nick Flaherty). Monitoring transmission lines can be challenging due to electromagnetic interference and they can be difficult for a UAV to see. “Our proposed system enables small UAVs to inspect transmission lines at close range for the first time,” said Satoshi Suzuki, associate professor at the Graduate School of Engineering, Chiba University in Japan. Measuring 0.24 x 0.24 x 0.15 m, the UAV has a 5 in propeller and a take-off weight of 0.484 kg. The platform (see diagram) consists of a GNSS receiver (a), a PLKLC2001l radar (b), an OAK-1 RGB camera (c) and the main control board (d). The system uses a low-cost global navigation satellite system (GNSS) receiver, RGB camera and a millimetre (mm)-wave radar to characterise the transmission lines. It uses this data in a knowledge-based line identification system, which employs a specialised technique called the Hough transform to identify and measure the distance between the transmission lines and the UAV, enabling it to fly in close. A heading correction module counters any magnetic-field interference affecting the UAV’s compass by calculating the desired direction, based on the identified transmission line’s start and end points, and correcting the vehicle accordingly. A waypoint correction system then addresses the mismatch between the planned and actual path of the UAV caused by the low accuracy of the GNSS receiver. An auxiliary controller is used to address any unknown disturbances during inspection, such as strong winds, which can deviate the UAV off its path. The team tested their designed UAV to inspect a 10 kV energised transmission line. Their experiments showed the proposed method effectively addressed magnetic interference problems, as well as any mismatches between the planned and actual path, and resisted wind interference. The GNSS receiver is mounted at the top of the platform to receive the satellite signals. During inspection, the quadcopter remains above the transmission line, so the mm-wave radar and camera are mounted on the bottom to capture or detect the line. The team removed the shell of the PLK-LC2001l and connected its core board directly to the main control board to reduce weight. Placed at the centre, the main control board integrates essential components such as an inertial measurement unit, barometer, compass and log record module to support autonomous flight. UAVs Low-risk line checkers The UAV inspected a 10 kV energised transmission line
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