Study On Method And Application Of Flatness Measurement Based On Double Laser Line And CCD For Hot-rolled Steel Strip

The demand of high quality hot rolled strip market, as well as the intelligent drive of Chinese manufacture 2015 and Industry 4.0, promote the transformation and upgrading of hot rolling production line for automation and intelligent rolling. In order to achieve the hot rolled strip surface flatness feedback control and to improve the surface quality of hot rolled strip, the real time measurement of strip flatness is the basic condition to realize the intelligent control technology of high quality hot rolling strip rolling. The domestic existing hot rolled strip flatness detection technology, due to the constraints of the hot rolled strip running fast, surface temperature, so far no a set of reliable measurement device or system operation for the production of hot rolled strip flatness. Therefore, it has important theoretical and practical significance to carry out the research on the flatness measurement mechanism and the realization technology of hot rolled strip.Hot rolling strip flatness double line laser CCD measurement technology is based on the principle of laser triangulation, which has the advantages of non-contact, fast response, large field of view, high-precision, strong anti-interference ability and so on. The basic technical route is through acquiring modulation of hot rolling steel strip deformation by laser line matrix CCD, through the camera coordinate system calibration and conversion, extraction of modulated laser deformation signal. After signal filtering, the fiber strip flatness signal on the surface of hot rolled strip is acquired. The key technologies involved in the double laser and CCD flatness measurement system includes: adaptive control of the sharpness of the modulated laser stripe, laser stripe feature point extraction, calibration of the optical imaging system, system modeling and filter design. In this paper, the adaptive control of laser stripe image, system modeling and filter design are studied. The main research contents and research results are as follows:(1) The sharpness evaluation model based on the maximum edge direction gradient of laser stripe image is established, and the threshold value and the region of interest(ROI) are introduced to improve the performance of the evaluation function. Image sharpness control system is established based on the sharpness evaluation model.(2) The double laser CCD homologous image information acquisition method and realization technology are put forward to establish the flatness measurement model based on homologous double lasers, and the mathematical model of the system is restructured based on the desired system state of flatness calculation.(3) The theoretical and experimental analysis of the problems existing in the filter design, and combined with the adaptive noise estimation, memory decay filtering algorithm and the variance evaluation of estimated value, Kalman filtering algorithm is proposed based on double laser line to improve the accuracy of flatness measurement.