Automatic Welding System Using Speed Controllable Autonomous Mobile Robot∗

A prototype of autonomous mobile robot with two vision sensors for automatic welding of steel plates was constructed. The robot can move straight, steer and turn around the robot center by controlling the driving speed of the two wheels respectively. At the tip of the movable arm, two CCD cameras are fixed. A local camera observes the welding line near the welding torch and another wide camera observes relatively wide area in front of the welding part. The robot controls the traveling speed in accordance with the shape of the welding line. In the case of straight welding line, the speed of the robot is accelerated and the welding efficiency is improved. However, if the robot finds a corner of welding line, the speed is decelerated in order to realize the precise seam tracking and stable welding. Therefore, the robot can realize precise and high speed seam-tracking by controlling the travel speed. The effectiveness of the control system is confirmed by welding experiments.