Defect detection in concrete structures using sensor fusion of force sensor and camera

Inspection of concrete structures such as tunnels and bridges is most often performed in outdoor environments where wind and vehicle noise are strongly present. Therefore, inspection methods must be robust against acoustic noise. The use of an impact hammer, which has a force sensor embedded in its head, has the advantage of being inherently robust against acoustic noise compared to the commonly used acoustic hammering inspection method while retaining the same ease of use. However, being able to capture data only during the short impact time, force sensor alone does not allow for acceptable defect detection. Therefore, in this study, the detection performance of defects was improved by considering the position of the crack on the concrete surface and the sample position obtained from a camera image in addition to the response of the force sensor of the impact hammer. From the experimental results obtained using concrete test blocks in laboratory conditions, the ability to detect defects with an impact hammer was significantly improved. © 2020 Japan Society for Precision Engineering. All rights reserved.