Non-contact overall 3D deformation measurement based on a multi-camera system for static testing of large aircraft wing structure

To obtain the certificate of airworthiness, it is essential to conduct a full-scale aircraft static test. During such test, accurate and comprehensive wing deformation measurement is crucial for assessing its strength, stiffness, and bearing capability. This paper proposes a novel and cost-effective videogrammetric method using multi-camera system to achieve the non-contact, high-precision, and 3D measurement of overall static deformation for the large-scale wing structure. To overcome the difficulties of making, carrying, and employing the large 2D or 3D target for calibrating the cameras with large field of view, a flexible stereo cameras calibration method combining 1D target and epipolar geometry is proposed. The global calibration method, aided by a total station, is employed to unify the 3D data obtained from various binocular subsystems. A series of static load tests using a 10-meter-long large-scale wing have been conducted to validate the proposed system and methods. Furthermore, the proposed method was applied to the practical wing deformation measurement of both wings with a wingspan of 33.6 m in the full-size civil aircraft static test. The overall 3D profile and displacement data of the tested wing under various loads can be accurately obtained. The maximum error of distance and displacement measurement is less than 4.5 mm within the measurement range of 35 m in all load cases. These results demonstrate that the proposed method achieves effective, high-accuracy, on-site, and visualized wing deformation measurement, making it a promising approach for full-scale aircraft wing static test.