A three-dimensional position measuring system

Abstract When checking robot performance, a measuring system with the ability to measure both the static and dynamic behaviour of a robot arm is essential. The system can also be used to check on robot performance and on validity of already developed models. This device should be able to measure the position of a fixed point on the robot arm, the so-called Tool Center Point, in three dimensions with an accuracy of 10µm, together with a large scale bandwidth of 30Hz. The device uses three identical laser-optical distance measuring systems, each of which measures the displacement of the Tool Center Point with respect to a reference point belonging to that system. Each distance measurement system consists of a frequency stabilized laser, a tracking system and a laser interferometer. A useful laser stabilization based on thermal expansion has been developed, as well as an interferometer detection unit and a bi directional interferometer counter.