A study on development of an H-infinity robust control system for arc welding

Arc welding is a complex process, the dynamics of which are affected by many manufacturing conditions that typically vary during welding or vary from application to application. Further, the modeling of the dynamics and design of the feedback control system require both advanced control theory and deep understanding of welding process principles. The feedback control system should be designed such that it can tolerate the variations in manufacturing conditions and the resultant process dynamics. This implies that robust control is a potential solution to address the conflict between the increasing demand of quality welds and the limited number of qualified personnel. Hence, this study develops a mathematical frame of robust control of welding processes for welding engineers who understand welding process principles and have elementary feedback control background. The control of the weld geometry is used as an example to demonstrate the details of the robust control principle and its implementation.