Research On 3D Vision Measurement Technology Of Aeroengine Blade Surface

The aero engine is the "heart" of the aircraft,and the blade is the key component of the aero engine.The measurement result of the blade directly affects the judgment of the quality and service life of the blade,so accurate three-dimensional measurement of the surface shape during the production and use of the blade is of great significance.Although the contact measurement of the blade is high in accuracy,but the measurement efficiency is low,and machine vision has the advantages of low cost and high measurement efficiency in non-contact measurement,this paper proposes an aero-engine blade measurement method based on machine vision theory.The binocular vision measurement method has the advantages of simple structure,low cost and high precision,and is widely used in the field of machine vision.A binocular vision measurement system using line structure light scanning is proposed.Firstly,the 3D scanning measurement system is designed for the principle and mathematical model of 3D measurement system,and the design indicators are given.The binocular camera calibration method is studied,and the double target method of parallel circular target is proposed.Secondly,the line structure light feature extraction and stereo matching technology are studied.The pre-processing algorithm of line structure light stripe image is studied.The peak signal-to-noise ratio of the three filtering methods is compared.The Gaussian filtering method is used to eliminate image noise.The global threshold segmentation algorithm separates the background interference fringe from the target fringe.Comparing the accuracy and running time of the two stripe centerline extraction algorithms,a thinning algorithm based on binary image is proposed to extract the line laser strip skeleton.The feature matching method is used to increase the polar line constraint condition to help determine the matching relationship between the corresponding points of the two images.The three-dimensional coordinates of the matching points are calculated by coordinate transformation.Finally,the threedimensional reconstruction of the engine blade surface is performed for the point cloud data.Since the surface of the engine blade is a complex curved surface structure,the blade is three-dimensionally reconstructed based on the NURBS surface fitting method,and it is quickly reconstructed by Geomagic Studio software.Calculate and analyze the measurement uncertainty of the 3D measurement system,and verify the overall uncertainty of the 3D measurement system through the 3D measurement uncertainty experiment and the standard cylindrical surface measurement uncertainty experiment.The final experimental results show that the measurement system can achieve high-precision three-dimensional measurement of the blade.