US Patent 9851164 Laser centering of robotic arm

In a system and method of working tubes coupled to a tubesheet having a number of holes, wherein each hole in fluid communication with one of the tubes, an end-effector is positioned by a robot in coarse or rough alignment with a first hole in the tubesheet. Via lasers positioned on the end-effector, laser spots are formed on a surface of the tubesheet adjacent the first hole. The laser spots are detected by a camera and the alignment of the end-effector relative to the first hole in the tubesheet is refined via the robot based on the detected pattern of laser spots. The tool is then moved into the tube that is in fluid communication with the first hole in the tubesheet to work on (inspect, plug, sleeve or weld) the tube.