A high-precision fitting method of assembly features for preassembly analysis of aircraft HUD components

The new generation of aeroplanes presents a stepwise development of high stealth, long range, and long life, which puts higher requirements on the precision of aeroplane assembly. Therefore, a virtual preassembly technology based on the measured model is investigated to achieve accurate quality control and traceability adjustment in the critical parts of the assembly, which require ultra-high precision, by accurately representing the part manufacturing errors and the cumulative assembly errors throughout the assembly process. However, the reconstruction accuracy of the measured model is crucial for accurately expressing part manufacturing errors. In this paper, a data processing and model reconstruction method is introduced. Through the alignment of measurement data and CAD model, manufacturing and Measurement errors are introduced, unqualified points are filtered, and redundant and mixed points are filtered to obtain high-quality point cloud data; a NURBS surface fitting algorithm based on the asymptotic iteration of the fitting accuracy is proposed to obtain the least-squares base plane through a quadratic polynomial to carry out the initial surface reconstruction, and then add the reconstruction accuracy and smoothness conditions to carry out the secondary surface reconstruction to improve the reconstruction accuracy of the model. Finally, a set of aircraft HUD system simulations is designed to validate the method, which proves its feasibility.