Nonlinear modelling and control of full-penetration dual bypass gas metal arc welding of aluminium

Dual bypass gas metal arc welding (DB-GMAW) is a novel welding process which is capable of achieving different full penetration level by adjusting bypass current while keeping the total welding current constant for a constant mass input. In this paper, an experimental system is constructed to implement DB-GMAW and full penetration weld is produced on aluminum. To describe the relationship between bypass current (input) and full penetration level (output), a nonlinear model is proposed, identified, and validated based on process analysis and through experiments. To assure the desired full penetration level be produced under varying welding conditions, the parameters are on-line identified/updated and an adaptive control algorithm is proposed. Experiments verified the effectiveness of the developed adaptive nonlinear control system.