This welding seam tracking system passes through the probe directly into the inner seam formed by the sensor in the up and down, left and right direction to acquire the welding voltage output balance changes in surface displacement. It is calculated by control system. Any time, the adjustment of the location of the torch and workpiece changes by actuator. Complete communication port can be connected to automatic welding machine to achieve high quality welding. It is applied to lap, fillet welding and butt welding with groove or gap.
