MEASURING ROBOT REPEATABILITY AN APPLICATION OF ISO AND ANSI STANDARDS

The paper presents the results of a study in which warm-up and repeata bility characteristics of an industrial robot were measured. To facili tate the study, two commonly available draft standards aimed at evalua ting the performance of robots were employed as case studies; in parti cular, ISO 9283 and ANSI/RIA R15.05. As a result, a comparison of the standards is made and areas that need improvement are revealed. In ord er to implement the proposals, two measuring systems capable of record ing robot repeatability with varying degrees of accuracy are introduce d. As they do not specify the type of measuring system to be used, the consequence of implementing the two systems will reveal significant d ifferences in the results obtained. Here, simulation results, along wi th experimental results, will demonstrate how the calculated value of repeatability varies as a function of measurement error. Also, the req uired number of cycles to capture long-term repeatability is investiga ted. Here, it is found that as many as 250 cycles may be required. Fin ally, the effect of varying the ambient temperature during testing is examined. Results show that changes of as little as 2 degrees C can si gnificantly affect robot end-effector positioning characteristics.