Product Code: ICAL07_1901

Perimetric Sensor for the Detection and Following of Complex Seam Trajectories in Robotic Laser Welding
Authors:
Dimitrios Iakovou, University of Twente; Enschede Netherlands
Johan Meijer, University of Twente; Enschede Netherlands
Ronald Aarts, Univercity of Twente; Enschede Netherlands
Ben Jonker, University of Twente; Enschede Netherlands
Presented at ICALEO 2007

The use of robotic laser welding is increasing among industrial applications, because of its ability to weld objects in three dimensions. Automatic seam detection and following can be accomplished with the aid of seam detection sensors. The majority of the available sensors apply optical triangulation with a single structured light line in order to detect the seam position. Such sensory systems can perform efficiently for the majority of cases. However, they suffer from serious limitations regarding the detection and following of complex seam trajectories. Single line triangulation sensors require maintaining a relative orientation towards the seam trajectory. This restriction can cause sharp corners not to be detected. But even when the sharp corner is known then the robot has to make fast rotations near the corner to keep the seam in the sensors field of view. This will introduce positioning errors at high speeds due to robot dynamics. Such positioning errors are undesirable during laser welding processes. This paper describes a multi-purpose tool with an integrated perimetric optical triangulation sensor. The integrated system consists of a laser welding head, with sensors for seam detection, inspection and weld process control. The structured light shape is projected around the laser tool centre point, and allows the system to detect sharp corners, but also to move along a seam without the necessity of maintaining a relative orientation. This reduces the positioning errors along the corners considerably as well as it simplifies the required robot joint rotations.