Jahanshahi, Hadi2026-07-062026-07-062026-05-28Jahanshahi, H., Alizadeh, M., & Zhu, Z. H. (2026). Hardware-in-the-loop emulation for 6-DOF free-floating spacecraft using active gravity compensation with a collaborative robot. Acta Astronautica, 247, 782–794. https://doi.org/10.1016/j.actaastro.2026.05.0581879-20300094-5765https://doi.org/10.1016/j.actaastro.2026.05.058https://hdl.handle.net/10315/43806© 2026 The Authors. Published by Elsevier Ltd on behalf of IAA. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ).This technical note presents a hardware-in-the-loop testbed that uses a UR10e collaborative robot to emulate 6-DOF free-floating spacecraft motion through active gravity compensation. Experimental validations across all three Cartesian axes demonstrated high translational fidelity with a mean speed correlation of 0.9992 between the measured robot trajectory and an independently initialized rigid-body simulation, low residual forces below the controller deadband, and minor rotational errors of 2° to 6° attributed to kinematic coupling through the robot joint structure. The platform provides a cost-effective testbed for ground-based emulation of free-floating spacecraft dynamics.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Free-floating spacecraftHardware-in-the-loop emulationGround testbedActive gravity compensationAdmittance controlSpace roboticsCollaborative robotMicrogravity emulationSpacecraft dynamicsRobot trajectory trackingArticle