Research On Design Of Focusing Module And Weld Tracking Technology Of Laser Welding Head

In recent years,with the development of industries such as automobiles and metal sheet metal,the requirements for welding quality,efficiency,and reliability have become higher and higher,and laser welding heads combined with industrial robot arms can well adapt to these demands.In order to make the laser welding head adapt to the welding seam change under different working conditions,this paper has carried out in-depth research on the design of the focusing module and the tracking technology of the welding seam of the laser welding head,mainly related to the three-dimensional design of the laser welding head structure,and the design of optical components.Simulation,vision system modeling,weld recognition and tracking algorithms,and axial radial focus control and experiments,and achieved corresponding research results.First,the overall design of the laser welding head was designed,including optical component design and three-dimensional design of the structure.Using Zemax optical simulation software,a reasonable overall optical path scheme and lens related parameters were obtained,and the relationship between the axis radial focus and the laser focus movement was designed.The experiment shows that both the theoretical and quantitative requirements are satisfied with the theoretical value,axial Linear negative correlation,radial positive linear correlation.The three-dimensional design software was used to design the module structure of the laser welding head.The focusing module was designed.The structure of the combination of the eccentric worm gear and the crank slider was used to meet the real-time control of the radial focusing eccentricity.Second,establish a mathematical model for the visual inspection system.According to the pinhole camera principle,the two-dimensional coordinates of the pixel coordinate system are solved and converted into the three-dimensional coordinates of the robot base coordinate system.Laser triangulation method was used to obtain the corresponding weld parameters.The line structure light measurement model is analyzed to obtain three-dimensional information of the weld feature points in the base coordinate system.A three-dimensional weld curve model was established using the B-spline function,and the least squares method was used to attenuate the noise and a real-time tracking model of the weld was obtained.Thirdly,the weld seam tracking method based on one-line laser illumination and CCD video imaging was designed,including image processing to extract the weld seam feature points and KCF(Kernelized Correlation Filter)target trackingalgorithm.The image processing method based on gray features was used to verify the results through Matlab programming.The KCF tracking algorithm was used to perform video positioning and tracking of the linear and curved welds.The experiments showed that the weld line and curve obtained by the CCD tracking match well with the actual weld line or curve.The effectiveness and accuracy of this seam tracking method.Finally,the axis radial focus experiment and error analysis were performed.Based on Labview and STM32,the hardware circuit and control software of the focusing module were designed.The error rate of the axial focusing experiment results and the simulation results was 7.8%,and the radial direction was only 3.3%,all within the error range.The analysis of the two main errors in the experiment shows that when the lens is off-center from the main optical axis and the lens is not strictly perpendicular to the main optical axis,it has a great influence on the position and size of the laser focus spot,thereby demonstrating the importance of lens mounting accuracy.