Development of Motion-Blur-Compensated High-Speed Moving Visual Inspection Vehicle for Tunnels

In Japan, many infrastructures are several decades old or more, and since those structures are gradually deteriorating, efficient and precise monitoring methods are strongly required for maintaining safety. In particular, tunnels on highways must be monitored regularly; however, frequent traffic restrictions should be avoided. Accordingly, visual inspection of tunnels from a moving vehicle is an efficient method for rapidly discovering faults. However, despite the need for high image quality, motion blur deteriorates the image quality considerably, especially under high-speed motion. In the work described in this paper, we developed a motion-blur-compensated visual inspection system that uses a motion blur compensation method based on the back-and-forth motion of a galvanometer mirror. In field trials using a system installed on an actual vehicle, we confirmed the effect of motion blur compensation when using scales attached to the ceiling of a tunnel. The vehicle on which the inspection system was installed exceeded the minimum speed for Japanese highways, and the system was capable of distinguishing black-and-white stripes with widths of 0.2 mm. Additionally, this method can be used with conventional systems. 