{HEAD ~ a reference plane} setting section for setting a virtual reference plane as a reference defining a geometric placement of an arc welding {TAIL ~ torch} relative to a workpiece during a welding operation, based on said plurality of position and orientation data obtained in said data obtaining section 
{ HEAD ~ a reference plane } setting section for setting a virtual reference plane as a reference defining a geometric placement of an arc welding { TAIL ~ torch } relative to a workpiece during a welding operation , based on said plurality of position and orientation data obtained in said data obtaining section
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH