Challenging issues and solutions of bridge inspection technology using unmanned aerial vehicles

It is expected that bridge inspection using unmanned aerial vehicles (UAVs) equipped with imaging devices is able to improve public safety and structural reliability by providing the close detail of a bridge appearance. Thus, interests in bridge inspection using UAVs are increasing worldwide. However, at present, most of them simply use commercially available UAVs to acquire images of parts of the bridge that are difficult to access (e.g., upper parts of the pylons in long-span bridges). It cannot meet the final goal of bridge inspection that is to assess the condition of the bridge. Therefore, this approach is still considered to be at an early stage from a practical point of view and a more systematic and reliable approach is needed. In this paper, challenging issues of bridge inspection using UAVs are identified and their solutions are presented. To this end, a recently launched research project is introduced by describing the developing core technologies such as a new UAV-localization algorithm without GPS, noncontact inspection techniques based on data fusion of hybrid images and a bridge condition evaluation technique based on the processed data originally obtained from UAVs. Some interim results of field tests are also presented.