Integral Sliding Mode Control for GMAW Systems

Abstract

Gas metal arc welding (GMAW) process is one of the most popular manufacturing processes in industries such as automotive, aerospace, ship buildings, and boiler. To increase the consistency in welding quality, the automation of the welding process with feedback controllers is inevitable. This paper presents an Integral Sliding Mode (ISM) controller, a robust controller, to control the welding current and arc voltage of a GMAW system. The concept of ISM controller design technique is to combine a discontinuous control with a nominal control to achieve robustness against matched perturbations. The proportional plus integral (PI) and composite nonlinear feedback (CNF) controllers are used as nominal controllers. It is shown in the paper that the CNF controller performs better than PI controller. A linear multi input multi output (MIMO) system model has been considered here for the design. The performance of the controller is analyzed in the presence of model parameter uncertainties and external disturbances and the simulation results are presented and discussed in order to establish a comparison framework.