Research On Nonlinear Error Model Of High Temperature Component Imaging

With the development of national industry and scientific and technological progress,the measurement of high temperature components has been widely used in aerospace,defense,automobile and forging fields.Compared with the traditional contact measurement method,non-contact visual measurement technology has many advantages such as high precision,fast speed and good repeatability.However,the high temperature and other harsh environments can have a great influence on the visual imaging effect during the components measurement,which affect the final measurement accuracy.In order to improve the imaging quality of vision measurement in high temperature environment,many domestic and foreign scholars have done a lot of related research work.However,there is not much research on the distortion of the image due to the imaging light refraction caused by the uneven temperature distribution in the component measurement.Therefore,the measurement error of the high temperature component represented by aero engine is the main research goal,and the nonlinear error compensation method of the high temperature component imaging is put forward.The research work mainly includes the following contents:Aiming at the requirement of high temperature component measurement,the measurement methods of different high-temperature components at home and abroad are summarized and analyzed,and the purpose and direction of the research are determined.By analyzing the radiation characteristics of the components under high temperature conditions,the spectral selective image acquisition method can be determined from the imaging window and the system light source.The high temperature radiation light imaging interference can be filtered out,but the measurement error caused by the high temperature caused by light refraction needs further study.According to the theory of heat transfer,the temperature distribution of the surrounding air of the component was simulated and calculated from the three ways of heat transfer for the high temperature plate test object.By using the simplest linear model and refractive index calculation model,the nonlinear refractive index distribution around the component is determined.According to the continuous refraction of light in inhomogeneous medium,a binocular vision measurement model for high temperature components is established.The deflection error of light in high temperature air and imaging plane is analyzed in detail from the initial incidence angle of light,the wavelength of light and the temperature of the component.At the same time,the reconstruction theory of binocular vision is applied to calculate the measurement error of objects under different parameters.It is found that when the measuring distance is fixed,the component temperature and the base distance between the two cameras will have a great influence on the imaging error.In this thesis,the measurement system of binocular vision of high temperature component is set up,and the center distance,length and width of the processing plate are respectively carried out in two environments: normal temperature and high temperature.Considering the high temperature error caused by thermal expansion,it is found that the measurement error is still 1.167%,0.229% and 0.358% after reconstruction,which proves that the nonlinear error in the visual imaging caused by high temperature refraction should not be ignored and need to be compensated.