The Robot AwardFirst Prize(Research and Development Category)A 4K high-resolution deformation detection systemfor concrete linings of expressway
tunnels traveling at 100km/h
Tokyo University /Central Nippon Expressway Company Limited

Detecting cracks 0.2mm and up froma vehicle traveling at 100km/h■A need for more frequent infrastructure inspections

About 30% of the tunnels on expressways have been in service formore than 30 years, and there is a need for more efficient
inspections to prevent accidents due to deterioration. Detailed
inspections of concrete tunnel lining are conducted by inspectors
once every five years, but from the perspective of cost andaccuracy, road administrators have been seeking a system thatenables more frequent and accurate inspections. A travelinginspection system has been available in the past, but this system
has been developed to meet the needs of users even better. The
system is capable of capturing high-resolution images of cracks as
small as 0.2mm while traveling at a speed of 100km/h. By
identifying deterioration and damage at a higher frequency without
the need for traffic control, special vehicles, or inspectors, thissystem will contribute to the achievement of a society in which asafe and strong infrastructure can be operated at a lower cost.

■4K High Resolution Deformation Detection System

This system uses a high-speed camera, high-speed image
processing, and a rotating mirror to compensate for motion blur inreal time, enabling the continuous capture of 4K-level images thatare comparable to still images. Using optical axis control
technology with the rotating mirror, they have succeeded inextending the exposure time, downsizing the equipment, andincreasing the resolution of the captured images. The higherresolution allows the system to be used even in areas where it isdifficult to see deformations due to soot and so on, and the longer
exposure time reduces the amount of light required, which helps
prevent distracted driving of other drivers and ensures the safety of
the inspector.
The device can be installed on the top of a regular vehicle (Toyota
Surf in the photo here) using a commercially available roof carrier.
Since patrol vehicles travel on highways many times a day, it ispossible to conduct inspections simply by mounting the device on
the vehicle and setting it to record.

Although only one camera is installed in order to reduce the size ofthe system, the servo motor switches the imaging angle in a circularpattern as the vehicle travels. Using real-time vehicle position
information gathered from the white line recognition, the system
accumulates data from the target angle, creating a development
view of the tunnel.

■Achievements and Future Developments

A field test was conducted on an unrestricted expressway. As aresult, the system was able to detect cracks of 0.2mm at a speed of
100km/h within the restriction of the Tomei Expressway Nihonzaka
Tunnel. In addition, development maps were successfully created
for the Kuragaike Tunnel on the Tokai Ring Road (at 100km/h) andthe Hida Tunnel on the Tokai-Hokuriku Expressway (at 70km/h). The
images were processed by the deformation detection program, andcracks of 0.2mm or larger were detected, confirming theeffectiveness of the system.
The system has succeeded in detecting not only cracks in tunnels
while in motion but also internal deformation such as floating andpeeling by applying the system to thermal camera imaging. In thefuture, the system is expected to contribute to the inspection field
where both high accuracy and high efficiency are required byapplying the same technology to inspection of transportation
infrastructures such as railways and airplane runways, as well as
high speed inspection of things like factory lines.
Principles ofoperation

Tunnel ceiling surface

High-speed camera
Following

Rotates with an actuator

White line
recognition
cameraSmall mirror

Move
RotateInspection
cameraInspection equipment set on the vehicle

Development view

A detected crack

Inspection system outline

University of Tokyo
Contact:

Address: School of Engineering Building 6, 7-3-1 Hongo, Bunkyo-ku, Tokyo
Tomohiko Hayakawa, Information Technology Center Tel: 03-5841-0024 E-mail: contact@ishikawa-vision.org

Central Nippon Expressway Company Limited

Address: 2-18-19 Nishiki, Naka-ku, Nagoya, Aichi
Hidemasa Onishi, Technology Planning and Development Division, Environment and Technology Planning Department, Technologyand Construction Headquarters Tel: 052-222-3623 E-mail: y.onishi.ac@c-nexco.co.jp
THE 9TH ROBOT AWARD

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