Research on refraction error correction of digital image correlation technology in strain measurement of airship skin

Abstract

Digital image correlation method is a widely used non-contact deformation measurement method. However, in low temperature environment the airships stay in, the camera needs to be protected by thermal insulation device, the optical glass of which introduces the refraction error to photogrammetry technology. To solve the influence of refraction error on the deformation measurement accuracy of digital image correlation method, the displacement deviation caused by refraction is theoretically deduced to obtain the deviation model based on the analysis of refraction light path and digital image correlation method. Moreover, the corresponding refraction error correction based on deformation function is proposed. Through the contrast experiment, it is found that the refraction offset error model is consistent with the actual displacement deviation. The digital image correlation method based on the refraction error correction proposed in this paper can effectively depress the refraction effect of glass, reduce the measurement error and improve the deformation measurement accuracy.