Dr. Gorazd Hlebanja, univ. dipl. inž., University of Novo Mesto, FME, Slovenia and Podkrižnik, d. o. o., Nazarje, Slovenia;
Miha Erjavec, univ. dipl. inž., Luka Knez, univ. dipl. inž., Simon Kulovec, univ. dipl. inž., vsi Podkrižnik, d. o. o., Nazarje, Slovenia;
Prof. em. dr. Jože Hlebanja, univ. dipl. inž., University of Ljubljana, FME, Slovenia

Abstract:
A design and development of a planocentric gearbox to be used in robot arm joints, namely for a collaborative robot, is presented in the papers. Besides strict limitations regarding the near zero backlash, the output position and torque should be available as well. So, a spatial-awareness encoder and a torque sensor are incorporated in a gearbox. The first assures an accurate absolute output position and the latter ensures information on actual output torque. The presented solution is based on the S-shaped tooth flank geometry. The near zero backlash requirement requires a tolerance analysis, which was accomplished by simulations in KissSoft software. The results of the analysis enabled a successful modification of the gearbox. A sophisticated testing rig was developed to verify actual gearbox characteristics, and to test its short-term and long-term behaviour. Backlash, stiffness, kinematic error, and dynamic behaviour of produced gear trains are measured in this way.

Keywords:
planocentric gear train, backlash, tolerance analysis, S-gearing, torque sensor, spatial-awareness sensor, testing rig