Homography-based measurement of bridge vibration using UAV and DIC method

•A homography-based method using UAV and DIC technique for the effective measurement of bridge vibration.•The feasibility of the method is demonstrated by testing structures.•Pros and cons, as well as the issues of practical implementation of the method, are discussed. This paper presents a homography-based method by combining an unmanned aerial vehicle (UAV) and the digital image correlation (DIC) together for vibration measurement of a bridge model. The videos of the bridge model captured by the UAV can be analyzed by the DIC method to track the displacement of the measurement points. Direct use of measured videos is usually impossible as the recorded data include the movement of the UAV itself. Here the geometric correction of images is achieved by establishing the plane homography transformation with fixed points and the real displacements of the bridge model can be obtained accordingly. The frequencies and mode shapes are subsequently extracted from the displacement time-histories of the target points. The effectiveness of the proposed method is validated against the fixed camera-based method. The work is important as it has great potential for real measurements in which otherwise difficult to access.