Vibration Region Extraction Method of Bridge Based on Ground-Based MIMO Radar

Ground-based multiple-input multiple-output (GB-MIMO) radar is suitable for vibration monitoring of all kinds of bridges because of its high accuracy, wide detection range and non-contact characteristics. It is necessary to select effective pixels with stable amplitude and regular phase to achieve accurate estimation of bridge vibration. In this paper, a new method for extracting vibration regions of bridges based on GB-MIMO radar is proposed. In the first step, the mask in image processing is combined with the average amplitude to extract the bridge pixels in the radar image and the circle fitting method is used to suppress the static clutter in the bridge pixel sequence. In the second step, the amplitude dispersion index is used to screen out the points with stable pixel amplitude. In the third step, the pixels with stable amplitude are divided into vibrational and non-vibrational regions by vibration similarity. Finally, the Welch method is used to analyze the phase spectrum of pixel sequence in the vibration region to estimate the vibration frequency. In order to verify the effectiveness of the proposed algorithm for bridge vibration detection, the measured data of a bridge in Chongqing is taken as an example to test the algorithm. The results show that the algorithm improves the effective detection rate of vibration region.