Modelling and control of consumable double-electrode gas metal arc welding process

Consumable double-electrode gas metal arc welding (DE-GMAW) is an innovative process, which offers unique advantages to increase productivity and reduce heat distortion. However, it must be appropriately feedback controlled for any practical use. To this end, the authors identified two critical variables as outputs for the control system to be developed. The control variables were then selected to ease the modeling and control design through establishing two decoupled SISO subsystems. Each SISO subsystem was modeled as an interval model, whose parameters were unknown but bounded by known intervals. The intervals were obtained through a set of designed step response experiments. A prediction based interval model control algorithm was then implemented to control the resultant interval models. Closed-loop control experiments verified the effectiveness of the developed control system for this novel welding process.