An adaptive seam tracker for welding heavy-section aluminum

Robotic welding systems which cannot adapt in real time to changes in the joint geometry along the weld seam and to the seam position itself have only limited success in many welding applications, due to heat distortion of the weldment or to an overall shift in the weld seam caused by fixturing errors. A solution to this problem requires the application of some form of adaptive joint geometry sensing system for guidance of the welding torch. Research is described that addresses the general aluminum welding problem by integrating a laser-based part-profiling sensor with a welding robot. An adaptive system is being developed that is referred to as ARTIST (Adaptive Real-Time Intelligent Seam Tracker). An IBM PC/AT-compatible microcomputer serves as the system supervisor, commands the motion of the robot, directs and processes the sensor scans, and establishes the required weld parameters. The programming language used in the microcomputers is C, chosen primarily for its flexibility and high execution speed. The host robot is a Unimate 760 Series electric six-axis articulated arm, using a VAL II controller