The Research Of Soft Measurement Of High-temperature Field Based On Digital Image Processing Technology

The non-contact soft measurement technology of high-temperature field based on digital image processing technology is a new method of radiation thermometry, which combines CCD(charge-coupled device) image sensor with modern optoelectronic image detection technology, digital image processing technology and the theory of heat radiation thermometry. It can realize a rapid and accurate measurement of temperature field and enhances the level of measurement technology significantly. Therefore it has become hot point in the research of high-temperature measurement field in recent years. In this paper, it is performed that in-depth theoretical analysis and lot of experimental studies on the soft measurement of the surface temperature field of radiator based on digital image processing technology.A method of adjusting combination of aperture and shutter automatically is proposed to solve the problems of narrow dynamic response range and small temperature measure range about CCD image sensor. The experimental results proved the practicability of the method.A fast image recognition method for high temperature object based on wavelet decomposition is proposed to solve the contradictions between the online real-time image processing of the high-temperature field soft measurement system and the slow speed of image recognition. Firstly, the grey level of the original histogram is reduced by using the wavelet decomposition, and so is the search area of the segmentation threshold. Then the segmentation threshold is found by applying the simplified method of Otsu's algorithm. Experimental results show that the method can calculate the best threshold segmentation accurately and computation speed can be increased significantly, thus greatly improving the image processing speed and real-time performance of the temperature measurement system.Two temperature calculation models are established. They are based on the error correction function K(T) and cubic polynomial fit, respectively. The validity and their respective advantages and disadvantages of the two temperature calculation models are compared in terms of the analysis of experimental data. The validity of cubic polynomial fit is proved in industrial furnace experiments.The soft measurement system of high-temperature field based on digital image processing technology is developed. The experiments are conducted on black-body furnace and industrial high-temperament furnace respectively. The experimental results show that the system can measure temperature with high accuracy, practicability, and a strong promotional value.