Silk-printed retroreflective markers for infrastructure-maintenance vehicles in curved tunnels

In this study, we developed a lane detection and motion-blur compensation system for curved tunnel inspection by combining elements from art discipline (silk printing), and a camera, aiming to improve the accuracy of the self-positioning method in tunnel. We proposed an accurate and convenient printing method that is based on silkscreen printing using retroreflective paint and developed a method for creating barcode markers that can be printed on the surface of concrete. Here, we propose an extension of the aforementioned study where different curvature angles are considered, revealing that the reading of the marker is significantly affected by the lighting and shooting conditions. The results of this recognition experiment show that the method of using such a retroreflective marker to identify the position of the surface of curved structures may be used not only for vehicle tunnels, but also for human and animal tunnels, and for narrower and more curved tubular objects.