Weld seams detection and recognition for robotic arc-welding through ultrasonic sensors

In robotic arc welding, sensors must be used to detect the position and orientation of a weld seam and determine its shape in order to carry out the weld parameter control. Useful measurements are the seam width and the volume of the seam that must be filled. With these measurements it is possible to set the welding parameters for each condition. In this paper an automatic seam detection and recognition system interfaced to a robot that uses ultrasonic sensors for obtaining the seam position and orientation, and its geometrical features, is described. The echo signals are digitized and through an analytical method the echo envelope and the moment of the arrival of the echo are precisely calculated. Echo amplitude is obtained searching the maximum of its envelope, and the range measurement is obtained known the starting time of the echo