Based On Visual Sensing Of Aluminum Alloy Robot Pulsed Mig Welding Pool Dynamic Model Identification

With the wide application of aluminum alloy to transportation and aircraft, it has become more and more popular for the use of robotic pulsed-MIG welding for aluminum alloy. Research about the controller designed in combination with modern control method for robotic pulsed-MIG welding is important in increasing production efficiency and solving stability of welding manufacture structure. Recently, extensive and thorough research is carried out on control of carbon steel pulsed GTAW. However, research on pulsed GTAW for aluminum alloy were still little and the research on pulsed GMAW for aluminum alloy is nearly blank. One factors is such as the surface of the aluminum alloy can reflect the visible light in whole wave range and the contrast between the weld pool and the plate nearly is very weak, so it is difficult to take the image of weld pool of aluminum alloy by ordinary visual sensor. The other reason is that the dynamic process of the weld pool is a high complex object with strong non-linearity, mult-variarble coupling and amount of stochastic and uncertain factors. It is very difficult to obtain an analysis mathematic model of weld pool dynamics. Thus the modeling of weld pool dynamics of pulsed-MIG welding for aluminum alloy becomes a puzzle problem for weld technique engineers and control system designers, which also is a essence handicap in weld automation.As technics research provides the foundation for capture of weld pool and modeling of weld pool dynamics, this paper deeply investigate influence of parameters of pulsed welding on weld line width and capture of weld pool.We have developed a special filter technology which solves interfered by electric arc and clear high contrast images of weld pool can be captured through the visual sensing method. Special image processing counting method to collect information of weld pool's feature.is also developed for the modeling of weld pool dynamics of pulsed-MIG welding for aluminum alloy and automatic controller designed to weld pool width.Drop transfer in the process of MIG welding is very complicated and quality of weld line is easily impacted by welding parameters coupled with each other. In order to well understand the speciality of weld pool dynamic and realize the effective control of the pulsed MIG process for aluminum alloy,this paper investigated the dymanic character of the pulsed MIG from the classic control systems, and obtained four SISO transfer function models by the system indentification method, these models for input base-current via output weld pool width, input wire feed ratio via output weld pool width, input pulse duty ratio via output weld pool width and input weld speed via output weld pool width. The established models in this paper would be useful to study the controlled performance of weld pool dynamic process in the pulsed MIG for aluminum alloy and can be used as valuable references and direction for designing its control system.Simulation reseraches on PID controller and intelligent controller for weld pool width of pulsed MIG has been put up in this paper based on the indentified function model. According to comparing PID controller with intelligent controller, the control properties of latter overmatch the former.