Multi-dynamic displacement measurement based on digital image processing technology

The multi-point dynamic-displacement data of structure is an important parameter for structural health monitoring. The difficulties of traditional multi-dynamic displacement measurement are reference point selecting and massive data processing. A novel multi-dynamic displacement measurement system was developed based on digital image processing technology. The calibration method based on surface fitting and window-centroid tracking algorithm was applied to determine the relationship between the object space and pixel coordinate system. The displacement data was acquired by comparing the change of the centroid pixel. The expectations based on wavelet coefficients were used for sub-pixel edge detection, measurement accuracy can reach 0.02 pixels. The dynamic displacement of four-layer steel frame structure was monitored on the shaking table. The results show that the system can achieve the monitoring of multi-channel 2-D dynamic displacements, the accuracy of displacement survey can reach 0.1mm.