Application of Satellite Time-Synchronized Digital Image Correlation for High-Precision Dynamic Measurement of Aircraft Exteriors

A study was conducted to assess the precision and reliability of digital image correlation (DIC) techniques in remote synchronous operations for external aircraft measurements with a wide field of view, validating their effectiveness and accuracy. The study established a measurement system using three-dimensional DIC, which transmitted real-time satellite time data obtained from a GPS clock source to a trigger unit, with a synchronization accuracy better than 1 microsecond. Unlike low-precision synchronization that relies on the local relative time of the computer, the method proposed in this paper solves the problem of high-precision absolute time synchronization of the left and right cameras in remote acquisition. To mitigate the influence of environmental temperature on measurement precision, we employed an active temperature compensation device. This device effectively reduced the DIC measurement error for rotational angles to less than 0.025 degrees. The reliability and precision of the method proposed in this paper were thoroughly examined, revealing an average angular accuracy of less than 0.02 degrees and a relative error of under 1%. Using the Stereo-DIC system, the accuracy of the measurements is clarified for specific conditions. Additionally, we use this system to measure simulated aircraft landing gear, which moves at an angular velocity of 52.4°/s over a distance of 5 m with a wide field of view of 16.8°. Through the above two experimental tests, the camera successfully acquired stable satellite time information and accurately captured the time targets, demonstrating the system's reliability for practical engineering applications. This research significantly contributes to the engineering utilization of Stereo-DIC for external aircraft measurements, showcasing its potential in real-world scenarios.