An Optimized Unmanned Aerial System for Bridge Inspection

This paper provides an innovative approach for conducting bridge inspections by optimizing an unmanned aerial system (UAS). A rotorcraft prototype, a camera gimbal mechanism, and a workflow is developed in this study. The rotorcraft is used to carry the camera gimbal for capturing images. Since visual inspection is a primary method of evaluating the structural conditions of a bridge, bridge inspectors need to work in dangerous environments such as cliffs and riversides. Current methods employ vehicles equipped with massive robot arms developed for lifting workers to the outbound of bridges, which increase the risk associated with an inspection. In addition, such methods are time, money, and labour intensive, and can be applied only on large-scale brides due to working space requirements. In order to develop a low-cost and more flexible approach, this paper offers an optimized UAS to acquire images of a bridge from underneath, and serve to provide a visual aid for bridge inspectors. An on-board camera gimbal mechanism is developed for acquiring stable image data and remote control. Furthermore, we designed a workflow for using this system based on our field test. The workflow included bridge investigation, path planning, image acquisition, and post processing. To verify the proposed approach, we tested our system on the Hsia-kuei Shan Bridge in Wulai, north of Taiwan. The results showed that the proposed approach can save costs and be efficient for bridge inspections.