Dynamic measurement of position and orientation of robots

A laser tracking system (LTS) capable of measuring the pose (position and orientation) of a robot moving along arbitrary paths is presented. The measurement principle is based on a modified triangulation. The laser beam is deflected over a cardanic-mounted mirror and follows a retroflector fixed to the robot´s end effector. The position of the center of the reflector is calculated from the interferometer distance data, the displacement of the reflected beam with reference to the emitted beam, and the angles of the cardan joint. The edges of the reflector are blackened and create a diffraction pattern within the cross section of the reflected laser beam. By evaluating this pattern using gray-scale image-processing methods, the orientation of the retroreflector can be determined