AN EXPERIMENTAL TEST-BED TO EVALUATE THE TOOL POSITIONING ERROR IN A REDUNDANT PARALLEL ROBOT FOR MILLING APPLICATIONS

Brian Juan Auza Tarquino¹; Tarcisio A. Hess-Coelho¹

¹ Escola Politécnica da USP

doi:10.20906/CPS/COB-2015-1136

Resumo

Serial mechanisms have been widely applied in industrial operations such as milling and positioning. On the other hand, in the last decades some investigations about parallel architecture have been also developed, due to the fact that they present some advantages in comparison with the serial. Fast motions, modular construction, lightness and high load capacity are some observed characteristics in pick-and-place parallel robots used in industry. Therefore, it is important to investigate and explore the performance of parallel mechanisms in different kind of operations where stiffness and precision are involved. In this manner, a parallel robot for milling applications was designed and constructed. Basically, it has only two axis for milling and its mechanical structure is fully modular. The topology of the parallel mechanism responsible for tool positioning corresponds to a planar redundant mechanism. In fact, it employs three active kinematic chains instead of only two. In order to investigate the positioning static error and the robot structure stiffness, an experimental test-bed has been built. Then, measurements of the tool positioning error are conducted in two conditions: unloaded and loaded. After collecting these data, the static error map is plotted for the robot available workspace. The static error mapping allows the robot user to select the best configurations, during motion planning phase, in terms of milling quality.

Palavras-chave: parallel robot; milling machine; didactic equipment