Applying Digital Image Correlation Method for Real-Time Feedback Control of Bridge with Neutral Equilibrium Mechanism

This study conducted experiments on a full-scale bridge structure under the control of a neutral equilibrium mechanism (NEM), which formed a virtual pier for the bridge, to explore the technical challenges and solutions in controlling the vertical displacement of bridges. The experiments revealed that the control effectiveness of the NEM system is hindered by the electromagnetic noise generated when the servo motor is activated, which interferes with the precision of traditional linear variable differential transformer displacement measurements, resulting in poor control performance of NEM. To address this issue, this study developed a rapid digital image correlation (DIC) method for displacement measurement, aiming to mitigate the impact of electromagnetic noise on displacement signals and improve displacement control effectiveness. The experimental results demonstrate that a bridge with NEM acting as a virtual pier control system, when utilizing the rapid DIC method for displacement measurement, can effectively mitigate the impact of noise, reduce the deformation caused by vertical loading, and ensure stable displacement control performance. Additionally, experiments with different proportional-integral-derivative gain coefficients indicate that the appropriate gain coefficient combination plays a crucial role in the system's stability. In practical applications, it is suggested to implement rapid DIC for displacement measurement and further adjust the gain coefficients to enhance the overall control performance of the system. This study provides a concrete and viable technical solution for the control performance of a bridge with NEM as virtual pier, offering practical insights for real-world applications.