Integrated Structural Monitoring of a Crawler Crane Based on Photogrammetry and Fiber Bragg Gratings

In this work, an integrated monitoring system was applied to the shape and strain monitoring of the base boom of a crawler crane. Two industrial cameras and 16 fiber Bragg grating (FBG) strain sensors were installed on the base boom. A simplified model of the main boom was established, the deflection and strain formulae were deduced, and a finite element simulation of the main boom was achieved. Loading tests of the crawler crane were done, and the images taken by the two cameras and the Bragg wavelengths of 16 FBG sensors under various loads and elevation angles were recorded. The marker point lines on the base boom displayed good linear relations, meaning that the bending strains of the base boom in the monitoring region were approximately zero. The 16 FBG sensors displayed their wavelength shifts (WLSs) with the loads and elevation angles in real time, and the change relations were consistent with the curves given by the theoretical model and the finite element simulations. The values of compression rigidity and bending rigidity of the base boom were obtained, by which the strain distribution along the base boom can be estimated.