Aerospace thin-walled components, such as aircraft skins, commonly use chemical milling techniques to create complex surface patterns. Therefore, accurately inspecting the processed patterns is crucial in ensuring the machining quality of the thin-walled parts. However, due to factors such as gravityand clamping forces, these parts are susceptible to bendingand deformation during the inspection process, leading to inconsistent detection results. Traditional methods often rely on custom fixtures that conform to the curved surface of the parts, which is both costlyand inefficient, and may not meet the rapid detection demands of industrial environments. To address these challenges, this paper proposes a novel chemical milling contour detection method for aircraft skins based on point cloud dimensionality reduction. This method innovatively reduces the dimensionality of the 3D surface contour to a 2D plane, thereby mitigating part deformationand enabling high-precision detection of complex surface patterns. Initially, the CAD standard contour of the skin surface is obtained as the reference data, and the pattern contour point cloud of the actual part is captured using structured light technology as the initial data. The geodesic distance matrix is then calculated based on the measured contour modeland the CAD model. Finally, both the measuredand standard contours are synchronously reduced to a 2D plane using the geodesic distance matrix, facilitating error analysis of the processed contour pattern. Experimental results demonstrate that the proposed method can achieve fixture-free detection of aircraft skin milling patterns with an accuracy of 0.039 mm.

Structured light method is one of the best methods for automated 3D measurement in industrial production due to its stability and speed. However, when the surface of industrial parts has high dynamic range (HDR) areas, e.g. rust, oil stains, or shiny surfaces, phase calculation errors may happen due to low modulation and pixel over-saturation in the image, making it difficult to obtain accurate 3D data. This paper classifies and summarizes the existing high dynamic range structured light 3D measurement technologies, compares the advantages and analyzes the future development trends. The existing methods are classified into multiple measurement fusion (MMF) and single best measurement (SBM) based on the measurement principle. Then, the advantages of the various methods in the two categories are discussed in detail, and the applicable scenarios are analyzed. Finally, the development trend of high dynamic range 3D measurement based on structed light is proposed.