Multiplexed and distributed control of automated welding

Although modern sensor technology and control algorithms have enabled in-process regulation of arc welding, classical single-torch actuation methods provide only a few welding conditions that can be modulated in real time to control multiple weld geometry characteristics. To decouple the process dynamics and simultaneously control thermal characteristics of the weld, multiple virtual heat inputs are implemented by rapid periodic reciprocation (timesharing) of the single torch on the weld surface. Dynamic analytical, numerical and linearized experimental process models are developed for the design of adaptive MIMO control systems of both geometrical and thermal characteristics, and their performance is tested in rejecting disturbances and following setpoint changes. To maximize the range of achievable weld features, a continuous heat distribution and temperature monitoring on the entire weld surface is finally adopted. The necessary vector-scanning trajectories of the torch are regulated in real time by a distributed-parameter control strategy, integrated to the weld design software for flexibility in production.<>