Research On Three-Dimensional Measurement Technology Of Metal Aerofoil Blades With Polarization Information

The measurement methods commonly used in the industry in the field of measuring complex metal surfaces such as metal blades and aircraft skins include: photogrammetry,binocular stereo vision and structured light technology.The above method is based on the brightness information of light.When a highly reflective area exists on the surface of the component to be measured,it will cause overexposure of the captured image,resulting in voids and discontinuities in the measurement data in the highly reflective area.In response to this phenomenon,this paper proposes a three-dimensional measurement method that integrates the polarization information of light.This method combines surface structured light three-dimensional measurement technology and polarization imaging technology organically,and uses surface structured light three-dimensional measurement technology to obtain holes with holes.The point cloud data and the gradient information of the highly reflective area obtained by the polarization imaging technology are processed by the surface integration operation to finally output a complete point cloud.1.The polarization three-dimensional measurement technology is introduced in detail.Aiming at the ambiguity problem in the calculation of the key parameter-the azimuth angle,a coding method of using the illumination coding method to obtain the north-south direction of the normal vector of each point on the surface is proposed to eliminate Ambiguity of azimuth;2.We summarize the theoretical key points in the structured light measurement technology and using obtained point cloud to obtain the zenith angle.performing curve fitting on the known zenith angle and polarization value pair to obtain the complex refractive index parameters,and solve the problem of unknown complex refractive index on the metal surface with different materials or processing technology;3.The point cloud boundary obtained by structured light is used to integrate the normal vector of the glare area obtained by polarization,which solves the problem that the integral boundary is difficult to obtain in the three-dimensional polarization measurement.At the same time,combined with the perspective projection model,the problem that the integration step length is unknown in the three-dimensional polarization measurement can be solved.The advantages of the two technologies are complemented,and the area measurement of the local glare area of the blade is completed.4.An experimental platform for three-dimensional measurement of blades fused with polarization information was built.The measurement experiments were carried out on mirror metal samples,semi-rough metal samples(high reflective),and rough metal samples(general reflective).Experiments show that the coded illumination method and metal surface complex refractive index correction model provided in this article are suitable for the measurement process of highly reflective metal materials.By fusing polarization measurement and surface structured light technology,it can effectively restore the highly reflective area of metal aviation blades.,Verifying the rationality of the fusion of polarization measurement and structured light measurement.