In the automatic pipeline welding systems, the mechanical properties and weld bead geometry are changed following to angle variation around the pipe. It occurred since during a weld pass, there are all of possible positions. In this work, first an augmented state-space model of process is presented that includes the travel motion and angle of robot. Also, gravitational force and arc voltage equations are modified. This model covers the free flight transfer modes (spray and globular). Then, accuracy of model is shown by model validation and comparing to real experiments. Finally, the angle effect on detachment is studied for all positions using simulation results. Detachment frequency variations, disturbance effects, and irregularity in detachments are analyzed using time–frequency representation.
