Design and development of a full 5-DOF testbed for testing nanosatellites formation flying, rendezvous and proximity operations

In this paper we present the concept design and the progress in the realization of a spacecraft motion simulator currently being developed by the School of Aerospace Engineering at “Sapienza” University of Rome. The facility is aimed at testing and validating guidance, navigation and control algorithms for nanosat formation flying, rendezvous and proximity operations. To simulate the spacecraft motion dynamics in the terrestrial environment the micro-gravity conditions must be recreated adequately. It means that the effect of the gravity force on both the translation and the rotation of the spacecraft simulator must be compensated or minimized. This goal is achieved through the interaction of the facility core subsystems: a 2-DOF air bearing table, reproducing the spacecraft planar translation on the horizontal plane, and a 3-DOF spherical air bearing, reproducing the spacecraft rotational motion around its center of mass. These two subsystems can operate both independently or simultaneously, thus allowing the spacecraft motion dynamics to be simulated up to 5-DOF. The design of the spacecraft motion simulator is presented with focus on the critical aspects of the project. These include the characterization of the air cushion and related effect on the design of the spherical air bearing, the realization of a balancing system necessary for minimizing the gravity torque and the remote control of the facility for calibration and test operations. Preliminary results from numerical simulations and tests are shown and discussed. Open issues are introduced and possible solutions are proposed