A study on development of inductive sensor for automatic weld seam tracking

An electromagnetic sensor consisting of one exciter and three separated (triple) detectors is developed for both tracking the weld seam of a workpiece and controlling the sensor-to-workpiece distance (height) simultaneously. The left and right detectors are used to track the seam, while the fore and right detectors allow the sensor to determine the height and gap width by being coupled their outputs together. A series of experiments with the proposed sensor located above a mild steel plate containing a seam are carried out to examine the effectiveness of the sensor. The results revealed that the proposed sensor could fairly well track the desired seam and also well control the height to be constant even when the gap width of the seam varied. The gap width can be also determined during the seam tracking and height control by using the sensor outputs. As a consequence, these can provide the developed sensor with substantial improvement for industrial uses with respect to the previous electromagnetic sensors being used for the weld seam tracking.