Cable force estimation method based on UAVs and EMD

To solve the problems of difficulty in deploying accelerometers in traditional cable force measurement, this paper proposes a cable force measurement method based on unmanned aerial vehicles (UAVs). This method first uses the Kanade-Lucas-Tomasi (KLT) optical flow method to track the vibration video of the bridge cable target points captured by the UAV, obtaining its displacement-time-history curve. Then, the empirical mode decomposition (EMD) is used to correct these curves to obtain the true displacement response of the target points. Finally, the operational modal analysis (OMA) is used to obtain the natural frequency of the cable from the displacement response, and the cable force is calculated accordingly. The experimental results show that the relative deviation of the measured natural frequency of the cable is within 5% compared with fixed cameras and accelerometers, indicating that the UAV can effectively obtain the natural frequency of the bridge cable and calculate the cable force.