Rule-based control of weld bead width in pulsed gas tungsten are welding (GTAW)

A rule-based control system of weld bead width is established for realizing in-process control of pulsed gas tungsten are welding. The system consists of a microprocessor-controlled power supply and working table, a solid state television camera, a high-speed analogue-to-digital converter and an image processing and control computer. Considering the characteristic of arc light and its influence on vision sensing, special measures were taken for image capturing, processing and weld bead width extraction. The rule-based model was combined with the principle of PID (proportional integral derivative) control, and a parameter-changing PID controller was designed. The bead-on-plate welding experiments were carried out. The results show that the system is of good adaptablity for in-process control of weld bead width in pulsed gas tungsten arc welding (GT AW).