Dynamic response and tension estimation of stay cables with disturbed images acquired from vision sensors

This study introduces a novel approach to measure cable responses of such bridges using a vision sensor comprising a digital camcorder mounted on a tripod. Prioritizing simplicity and efficiency, this setup requires minimal equipment. The sensor is strategically positioned to ensure the target cable remains within the camcorder’s field of view. However, operational bridge imagery is frequently disturbed by vehicular traffic, leading to defocusing and blurring due to the camcorder’s automatic focus adjustments. These disturbances complicate the identification of reference points essential for accurate cable response measurements, potentially skewing results. To address this, we apply an image quality evaluation method to distinguish reference points from disturbed images, mitigating the impact of these disturbances on measurement accuracy. We evaluated the method’s effectiveness in estimating cable tension under disturbances by capturing images of an operational cable-stayed bridge experiencing ambient vibrations. Cable tension estimations were derived from the analysed responses using the vibration method and validated against data from a long-term monitoring accelerometer. This comparison highlights the potential of the proposed vision sensor method to enhance the accuracy of cable tension measurements in cable-stayed bridges, even in the presence of disturbed images.