An Optimized Unmanned Aerial System for Bridge Inspection

This paper provides an innovative approach for bridge inspection by optimizing unmanned aerial system (UAS). A rotorcraft prototype, a camera gimbal mechanism and a workflow is developed in this research. The rotorcraft is used to carry the camera gimbal for capturing image. Since visual inspection is a main method to evaluate the structural conditions of a bridge, engineers need to work in dangerous environment such as cliff and riversides. Current methods use vehicles equipping with massive robot arms developed for lifting workers to the outbound of the bridge which increasing the risk the inspection. Also, such methods cost lots of time, money, labors, and can be applied only on large-scale brides (4 lanes at least) due to the requirements of working space. In order to develop a low-cost and more flexible approach, this paper offers an optimized UAS to get the image of the bridge from beneath. It provides a visual aid for engineers. An onboard camera gimbal mechanism is developed for acquiring stable image data and remote control. Furthermore, we designed a workflow of using this system based on our field test and user test. It included preparation, image acquisition, and post processing. To verify the proposed approach we have tested our system on two bridges, one large-scale and one small-scale, located in Yilan county, east of Taiwan. The result showed that the proposed approach can be a cost saving on large-scale bridges inspection and can work efficiently on small-scale bridges.