Research On Grid Line Alignment Detection System Based On Machine Vision

Due to the ever-decreasing of traditional non-renewable energy and its damage to the ecological environment,in many new energy sources,solar energy is considered to be the most promising new energy in the future,the solar cell which is a carrier for solar photovoltaic power generation,has a photoelectric conversion efficiency of 15% to 25% within a relatively long period of time due to process limitations.In order to effectively improve the photoelectric conversion efficiency of solar cells,in recent years,the “The double screen printing” method in which the grid lines on the cell sheet are printed once after the printing back silver process has been studied,the purpose of further increasing the photoelectric conversion efficiency of the cell sheet is to increase the height of the gate line.In the double screen printing process of the solar cell,a very precise alignment is required between the second printing gate line and the first printing grid line.In this paper,the research of grid line alignment detection system based on machine vision is carried out,high-efficiency requirements for the double screen printing process,through the cooperation with automation,a high precision alignment detection of the double screen printing is achieved.Specific research content includes:In-depth understanding of the influencing factors of solar cell wafer printing process and efficiency,Comparing and analyzing the experiments,The feature line segments for machine vision inspection were designed on the printing screen plate,and four cameras were designed for high-precision alignment detection.Collect the detection scheme of the feature line segment area in the four corners of the cell.Based on the hardware selection of the system,an overall inspection platform was built.In view of the problem of camera imaging distortion,Based on the traditional camera calibration algorithm,this paper proposes a multi-view four-camera calibration algorithm based on HALCON,including the calibration board design,calibration algorithm research.The overall detection algorithm was designed on the basis of the calibration,and elaborated in detail.Linear XLD fitting algorithm based on Tukey method to reduce outliers is used to fit the detected grid lines to meet the requirements of detection accuracy.Using the machine vision software HALCON and C# language mixed programming to complete the algorithm design,in the.Net platform WinForm development framework to build a software interface,and complete the entire system logic layer through C # language.Its interface is beautiful and the function is rich and practical.After testing on the factory production line,the system speed and detection accuracy meet the production needs.