The modelling and control of the welding process are crucial and challenging issues in automated welding. However, many uncertainties are encountered during welding that will change the seam state, such as the existence of a seam gap. The seam gap is one of the most important measurable parameters that influence the dynamic process of welding. Benefitting from research on hybrid systems, the present study proposes a kind of mixed logic dynamical (MLD) model to describe the interrelationship between process parameters and seam gap in pulsed gas tungsten arc welding (GTAW). Random experiments have been designed to excite the dynamics of the GTAW process for different gap widths and the effectiveness of the MLD model is illustrated by evaluating the back-side width of the weld seam. Finally, the stability and reliability of the MLD model are tested against an experiment with proportional—integral—differential control.
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