Detection and analysis of acoustic characteristics for loose bolts on transmission towers

Transmission towers serve as critical components of power-transmission lines. Their structural integrity, inclination and other conditions are closely related to the safe operation of power-transmission lines. In engineering practice for loose-bolt detection on transmission towers, merely achieving qualitative judgment of “loose or not” cannot satisfy operation-and-maintenance requirements. It is essential to further locate the exact positions of loose bolts so that maintenance personnel can accurately identify hidden hazards. This paper proposes a two-level technical route of “feature extraction-sound source localization”. First, continuous knocking and steady-state excitation are adopted to trigger structural acoustic-vibration responses, and time-frequency features specific to bolt looseness are extracted. Then, beamforming-based sound-source localization technology using a microphone array is employed to precisely locate fault characteristic frequencies, so as to realize accurate positioning of loose bolts.