A Microgravity Experiment for Validating Rigid-Body Simulation of Deployable Mechanisms

Validating physics engines under microgravity conditions is critical for designing and controlling robotic systems in space, where friction, joint clearance, and contact can strongly influence system behavior. However, a lack of experimental data has limited efforts to validate and benchmark these simulators in flightrelevant environments. This work presents the design and execution of a free-floating microgravity experiment conducted on a parabolic flight to generate a dataset for validating rigid-body simulations. The experiment captures the centripetal deployment of three deployable mechanisms: a translational scissor, a polar scissor, and a pop-up extending truss (PET), using synchronized high-speed video and motion-capture sensors. We utilize multi-view reconstruction techniques to convert image data into 3D trajectory data of rigid elements across deployment. This dataset is used to validate the Dojo physics engine, which models full multi-rigid-body dynamics, including contact, joint friction, and clearance. By optimizing simulation parameters to match experimental trajectories, the accuracy of the model is quantified to assess sim-to-real alignment. Initial results show $\mathbf{1. 3 c m}$, 1.2cm, and 4.4cm RMSE for the scissor, polar scissor, and PET systems, respectively. This work contributes one of the first publicly documented microgravity datasets for evaluating rigid-body simulators and demonstrates a repeatable experimental framework for validating space robotics.