Design and realization of videometric system for structural displacement measurement

Measurement of 3 dimension structural displacement with wide range and high precision is needed in the manufacturing process of large airplanes. For the displacement measurement requirement of airplanes and other great engineering structures, a videometric system of structural displacement was designed and implemented. The system adopted several digital cameras to take photos of the cooperative mark-points located on the frame and wing of the tested airplane from different directions, the parameters of the cameras were calibrated before the test, the image sequences acquired by the cameras were analyzed in real time during the test, the 2-dimension coordinates in the images of the mark-points were detected and tracked. Based on the cameras parameters and markpoints 2-dimension coordinates, the 3-dimension coordinates of the mark-points were calculated, then the displacement and deformation of the structure were obtained, the 3-dimension results were visually provided, and the displacement curve was examined. The test results showed the standard deviation of systems displacement measurement error is less than 1mm, and the relative error is less than 1%. The system was used in the wing displacement measurement of a specific airplane, and the efficiency and precision of the measurement were improved.