European Robotic Arm (ERA) manipulator joint system motor unit and tribological brake

Europe’s interest in in-orbit operations has extended over many years and, as part of the European contribution to the Russian segment of the International Space Station ‘Alpha’ (ISSA), expanded to include the European Robotic Arm (ERA). Included within the ERA system are the various subsystems and units, within which the Manipulator Joint System (MJS) Motor Unit (MoU) is integrated. The complete ERA includes seven MoUs. Designed, integrated and tested by ETEL SA, the MoU incorporates : a medium speed, permanent magnet synchronous motor (often called a 'brushless DC' motor); a friction brake; a speed-one resolver; and a 'State-of-the-Art' control/drive electronics. This paper will present the details inherent in the design of each of the Motor Units' electromechanical elements, in particular the tribological brake; the results obtained from both the development and qualification testing campaign at unit level; particular lessons learned and the conclusions drawn. In parallel, the electronic circuit protection philosophy and the overall mass and power budgets will be presented.