Abstract: The existing portal crane main girder deflection measurement method has many problems such as complicated operation, insufficient safety, long downtime and unstable accuracy. This paper proposes a fast, safe and accurate method for measuring the deflection of main girders based on binocular photogrammetry. Camera calibration is one of the most important influences on the accuracy of binocular photogrammetry. A cosine function convergence factor is introduced into the traditional grey wolf optimizer (GWO) to improve the global and local search capabilities of the algorithm, and a proportional weighting strategy based on Euclidean distance is used to speed up the convergence of the algorithm to obtain improved grey wolf optimizer (IGWO). The improved algorithm is applied to the calibration parameter search of the binocular camera to obtain the optimal calibration value. The simulation and field experiment results show that the proposed method is accurate and fast, and the deflection detection error is within 1%, which fully meets the engineering measurement requirements of portal crane deflection.
Keywords: portal crane; main girder deflection measurement; binocular photogrammetry; grey wolf optimizer (GWO)