Real-Time Identification of Time-Varying Cable Force Using an Improved Adaptive Extended Kalman Filter

The real-time identification of time-varying cable force is critical for accurately evaluating the fatigue damage of cables and assessing the safety condition of bridges. In the context of unknown wind excitations and only one available accelerometer, this paper proposes a novel cable force identification method based on an improved adaptive extended Kalman filter (IAEKF). Firstly, the governing equation of the stay cable motion, which includes the cable force variation coefficient, is expressed in the modal domain. It is transformed into a state equation by defining an augmented Kalman state vector with the cable force variation coefficient concerned. The cable force variation coefficient is then recursively estimated and closely tracked in real time by the proposed IAEKF. The contribution of this paper is that an updated fading-factor matrix is considered in the IAEKF, and the adaptive noise error covariance matrices are determined via an optimization procedure rather than by experience. The effectiveness of the proposed method is demonstrated by the numerical model of a real-world cable-supported bridge and an experimental scaled steel stay cable. Results indicate that the proposed method can identify the time-varying cable force in real time when the cable acceleration of only one measurement point is available.

Automated summary

This paper proposes an improved adaptive extended Kalman filter (IAEKF) method for real-time identification of time-varying cable force. The proposed method recursively estimates and closely tracks the cable force variation coefficient, considering an updated fading-factor matrix and determining the adaptive noise error covariance matrices through an optimization procedure. The effectiveness of the method is demonstrated using a numerical model of a real-world cable-supported bridge and an experimental scaled steel stay cable, showing that it can accurately identify the time-varying cable force when the cable acceleration of only one measurement point is available.