A LASER TRACKING SYSTEM TO MEASURE POSITION AND ORIENTATION OF ROBOT END EFFECTORS UNDER MOTION

This article describes a laser tracking system (LTS) that can be used to determine the position and orientation of a robot's end effector wi th high accuracy during arbitrary robot motions. The position is measu red using a polar configuration employing one laser beam and two rotar y axes. A retroreflector in the robot end effector reflects the laser beam and constitutes the only part the robot has to carry for the cont actless measurement. The orientation is determined by analyzing the in tensity profile of the reflected laser beam with a vision system. The intensity profile carries diffraction patterns of the retroreflector e dges that uniquely define orientation. The tracking unit allows the sy stem to follow arbitrary movements of the robot. With these characteri stics a six-degree-of-freedom (6-DOF) real-time robot measurement syst em is provided that can dynamically track robot motions.