Laser Interferometer to Measure the Position of a Robot Arm

摘要

A system for the precise static and dynamic measurement of the position of a fixed point on a moving robot arm was designed and partially realized. The position of this so-called tool center point (TCP) has to be measured in 3 dimensions with an accuracy of 10 microns and a 30 Hz bandwidth. The device uses three identical laser interferometric distance measuring systems each of which measures the displacement of the TPC with respect to a reference point belonging to that system. Each distance measuring system consists of a frequency stabilized laser, a tracking system, and an interferometer. A laser stabilization, based on thermal expansion, and an interferometer detection unit were developed. The testing of a tracking system with a loudspeaker as actuator does not show satisfactory results. An error analysis shows that a 10 micron accuracy for the whole system is feasible.