MIMO Direct Model Reference Adaptive Control for Gas Metal Arc Welding

This paper presents the design and implementation of a Direct Model Reference Adaptive Control (DMRAC) for a GMAW process. A recently developed highly nonlinear fifth order mathematical model for the GMAW process is considered. After simplifications and linearization are performed, the process is modeled as two-input two-output second order system of differential equations. Current and arc voltage are the process outputs, which are controlled by open circuit voltage and wire feed speed, which are chosen as the process control inputs. After the DMRAC is designed, it is implemented on the actual GMAW process. Satisfactory experimental results are obtained. Hence, this new direct adaptive control algorithm allows the control of both current and arc voltage and consequently makes possible to achieve high quality weldings in GMAW processes.