Detachment Diagnosis for the External Tile Finishing Wall Using Spatula Mounted on Wall-contact type UAV

Abstract

In Japan, the Building Standards Act mandates periodic inspections of external tile walls. Conventional hammering tests require scaffolding, resulting in high cost and labor intensity. As an efficient and safer alternative, drone-assisted hammering inspections have been studied. Previous research identified lightweight stainless-steel spatulas as effective for detecting tile detachment; however, the optimal dimensions for acoustic diagnosis and their applicability to wall-contact drones remain unclear.This study aims to identify the most suitable spatula dimensions for acoustic detection of tile detachment and evaluate their performance when mounted on a drone. Experiments were conducted on tile wall specimens with artificial detachment zones. Spatulas of varying lengths and widths were slid over tile joints under constant contact pressure to simulate tapping and generate repetitive impact sounds. The recorded sounds were analyzed using Fast Fourier Transform (FFT) to calculate average sound pressure levels in two frequency bands, Δf1​ (1000-2000 Hz) and Δf2​ (4000-5000 Hz). Results indicated that a 30 mm x 15 mm spatula produced the largest difference in sound pressure level (up to 16 dB) between normal and detached areas, and 5 dB when mounted on a drone. These findings demonstrate the feasibility of drone-based acoustic detachment diagnosis using optimally dimensioned spatulas.