Meet Weldguide IV: a powerful thru-arc sensor for robotic welding systems that guides robots to the correct path. Weldguide IV is more cost effective compared to optical sensors and yields fast, accurate results. Weldguide IV is easy to install and program (offline/online). It is capable of tracking difficult welding joint variations (has 6 tracking modes).
The above video shows what Weldguide IV is all about.